VENDOR intensifies

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/README.md

@@ -0,0 +1,11 @@
+MongoDB Go Driver Low-Level Driver Library
+==========================================
+The packages within this library allow users to build applications using a low-level driver
+interface. Knowledge of the internals of a MongoDB driver are assumed, so this library contains
+advanced features. The aim of this library is to provide an easy to use, high performance
+implementation of a low-level driver.
+
+This Library's API is experimental and subject to change. Packages may be changed or removed without
+notice. These APIs are not stable and do not guarantee backward compatibility.
+
+**THIS LIBRARY IS EXPERIMENTAL AND SUBJECT TO CHANGE.**

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/abort_transaction.go

@@ -0,0 +1,74 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// AbortTransaction handles the full cycle dispatch and execution of abortting a transaction
+// against the provided topology.
+func AbortTransaction(
+	ctx context.Context,
+	cmd command.AbortTransaction,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+) (result.TransactionResult, error) {
+	res, err := abortTransaction(ctx, cmd, topo, selector, nil)
+	if cerr, ok := err.(command.Error); ok && err != nil {
+		// Retry if appropriate
+		if cerr.Retryable() {
+			res, err = abortTransaction(ctx, cmd, topo, selector, cerr)
+		}
+	}
+	return res, err
+}
+
+func abortTransaction(
+	ctx context.Context,
+	cmd command.AbortTransaction,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	oldErr error,
+) (result.TransactionResult, error) {
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		// If retrying server selection, return the original error if it fails
+		if oldErr != nil {
+			return result.TransactionResult{}, oldErr
+		}
+		return result.TransactionResult{}, err
+	}
+
+	desc := ss.Description()
+
+	if oldErr != nil && (!topo.SupportsSessions() || !description.SessionsSupported(desc.WireVersion)) {
+		// Assuming we are retrying (oldErr != nil),
+		// if server doesn't support retryable writes, return the original error
+		// Conditions for retry write support are the same as that of sessions
+		return result.TransactionResult{}, oldErr
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.TransactionResult{}, oldErr
+		}
+		return result.TransactionResult{}, err
+	}
+	defer conn.Close()
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/aggregate.go

@@ -0,0 +1,204 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// Aggregate handles the full cycle dispatch and execution of an aggregate command against the provided
+// topology.
+func Aggregate(
+	ctx context.Context,
+	cmd command.Aggregate,
+	topo *topology.Topology,
+	readSelector, writeSelector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	registry *bsoncodec.Registry,
+	opts ...*options.AggregateOptions,
+) (*BatchCursor, error) {
+
+	dollarOut := cmd.HasDollarOut()
+
+	var ss *topology.SelectedServer
+	var err error
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		writeSelector = cmd.Session.PinnedServer
+		readSelector = cmd.Session.PinnedServer
+	}
+	switch dollarOut {
+	case true:
+		ss, err = topo.SelectServerLegacy(ctx, writeSelector)
+		if err != nil {
+			return nil, err
+		}
+	case false:
+		ss, err = topo.SelectServerLegacy(ctx, readSelector)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	defer conn.Close()
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return nil, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	aggOpts := options.MergeAggregateOptions(opts...)
+
+	if aggOpts.AllowDiskUse != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"allowDiskUse", bsonx.Boolean(*aggOpts.AllowDiskUse)})
+	}
+	var batchSize int32
+	if aggOpts.BatchSize != nil {
+		elem := bsonx.Elem{"batchSize", bsonx.Int32(*aggOpts.BatchSize)}
+		cmd.Opts = append(cmd.Opts, elem)
+		cmd.CursorOpts = append(cmd.CursorOpts, elem)
+		batchSize = *aggOpts.BatchSize
+	}
+	if aggOpts.BypassDocumentValidation != nil && desc.WireVersion.Includes(4) {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*aggOpts.BypassDocumentValidation)})
+	}
+	if aggOpts.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return nil, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(aggOpts.Collation.ToDocument())
+		if err != nil {
+			return nil, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if aggOpts.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*aggOpts.MaxTime / time.Millisecond))})
+	}
+	if aggOpts.MaxAwaitTime != nil {
+		// specified as maxTimeMS on getMore commands
+		cmd.CursorOpts = append(cmd.CursorOpts, bsonx.Elem{
+			"maxTimeMS", bsonx.Int64(int64(*aggOpts.MaxAwaitTime / time.Millisecond)),
+		})
+	}
+	if aggOpts.Comment != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"comment", bsonx.String(*aggOpts.Comment)})
+	}
+	if aggOpts.Hint != nil {
+		hintElem, err := interfaceToElement("hint", aggOpts.Hint, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, hintElem)
+	}
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	if err != nil {
+		if wce, ok := err.(result.WriteConcernError); ok {
+			ss.ProcessWriteConcernError(&wce)
+		}
+		closeImplicitSession(cmd.Session)
+		return nil, err
+	}
+
+	if desc.WireVersion.Max < 4 {
+		return buildLegacyCommandBatchCursor(res, batchSize, ss.Server)
+	}
+
+	return NewBatchCursor(bsoncore.Document(res), cmd.Session, cmd.Clock, ss.Server, cmd.CursorOpts...)
+}
+
+func buildLegacyCommandBatchCursor(rdr bson.Raw, batchSize int32, server *topology.Server) (*BatchCursor, error) {
+	firstBatchDocs, ns, cursorID, err := getCursorValues(rdr)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewLegacyBatchCursor(ns, cursorID, firstBatchDocs, 0, batchSize, server)
+}
+
+// get the firstBatch, cursor ID, and namespace from a bson.Raw
+//
+// TODO(GODRIVER-617): Change the documents return value into []bsoncore.Document.
+func getCursorValues(result bson.Raw) (*bsoncore.DocumentSequence, command.Namespace, int64, error) {
+	cur, err := result.LookupErr("cursor")
+	if err != nil {
+		return nil, command.Namespace{}, 0, err
+	}
+	if cur.Type != bson.TypeEmbeddedDocument {
+		return nil, command.Namespace{}, 0, fmt.Errorf("cursor should be an embedded document but it is a BSON %s", cur.Type)
+	}
+
+	elems, err := cur.Document().Elements()
+	if err != nil {
+		return nil, command.Namespace{}, 0, err
+	}
+
+	var ok bool
+	var namespace command.Namespace
+	var cursorID int64
+	batch := new(bsoncore.DocumentSequence)
+
+	for _, elem := range elems {
+		switch elem.Key() {
+		case "firstBatch":
+			arr, ok := elem.Value().ArrayOK()
+			if !ok {
+				return nil, command.Namespace{}, 0, fmt.Errorf("firstBatch should be an array but it is a BSON %s", elem.Value().Type)
+			}
+
+			batch.Style = bsoncore.ArrayStyle
+			batch.Data = arr
+		case "ns":
+			if elem.Value().Type != bson.TypeString {
+				return nil, command.Namespace{}, 0, fmt.Errorf("namespace should be a string but it is a BSON %s", elem.Value().Type)
+			}
+			namespace = command.ParseNamespace(elem.Value().StringValue())
+			err = namespace.Validate()
+			if err != nil {
+				return nil, command.Namespace{}, 0, err
+			}
+		case "id":
+			cursorID, ok = elem.Value().Int64OK()
+			if !ok {
+				return nil, command.Namespace{}, 0, fmt.Errorf("id should be an int64 but it is a BSON %s", elem.Value().Type)
+			}
+		}
+	}
+
+	return batch, namespace, cursorID, nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/batch_cursor.go

@@ -0,0 +1,454 @@
+package driverlegacy
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/wiremessage"
+)
+
+// BatchCursor is a batch implementation of a cursor. It returns documents in entire batches instead
+// of one at a time. An individual document cursor can be built on top of this batch cursor.
+type BatchCursor struct {
+	clientSession        *session.Client
+	clock                *session.ClusterClock
+	namespace            command.Namespace
+	id                   int64
+	err                  error
+	server               *topology.Server
+	opts                 []bsonx.Elem
+	currentBatch         *bsoncore.DocumentSequence
+	firstBatch           bool
+	batchNumber          int
+	postBatchResumeToken bsoncore.Document
+
+	// legacy server (< 3.2) fields
+	batchSize   int32
+	limit       int32
+	numReturned int32 // number of docs returned by server
+}
+
+// NewBatchCursor creates a new BatchCursor from the provided parameters.
+func NewBatchCursor(result bsoncore.Document, clientSession *session.Client, clock *session.ClusterClock, server *topology.Server, opts ...bsonx.Elem) (*BatchCursor, error) {
+	cur, err := result.LookupErr("cursor")
+	if err != nil {
+		return nil, err
+	}
+	if cur.Type != bson.TypeEmbeddedDocument {
+		return nil, fmt.Errorf("cursor should be an embedded document but it is a BSON %s", cur.Type)
+	}
+
+	elems, err := cur.Document().Elements()
+	if err != nil {
+		return nil, err
+	}
+	bc := &BatchCursor{
+		clientSession: clientSession,
+		clock:         clock,
+		server:        server,
+		opts:          opts,
+		firstBatch:    true,
+		currentBatch:  new(bsoncore.DocumentSequence),
+	}
+
+	var ok bool
+	for _, elem := range elems {
+		switch elem.Key() {
+		case "firstBatch":
+			arr, ok := elem.Value().ArrayOK()
+			if !ok {
+				return nil, fmt.Errorf("firstBatch should be an array but it is a BSON %s", elem.Value().Type)
+			}
+			bc.currentBatch.Style = bsoncore.ArrayStyle
+			bc.currentBatch.Data = arr
+		case "ns":
+			if elem.Value().Type != bson.TypeString {
+				return nil, fmt.Errorf("namespace should be a string but it is a BSON %s", elem.Value().Type)
+			}
+			namespace := command.ParseNamespace(elem.Value().StringValue())
+			err = namespace.Validate()
+			if err != nil {
+				return nil, err
+			}
+			bc.namespace = namespace
+		case "id":
+			bc.id, ok = elem.Value().Int64OK()
+			if !ok {
+				return nil, fmt.Errorf("id should be an int64 but it is a BSON %s", elem.Value().Type)
+			}
+		case "postBatchResumeToken":
+			pbrt, ok := elem.Value().DocumentOK()
+			if !ok {
+				return nil, fmt.Errorf("post batch resume token should be a document but it is a BSON %s", elem.Value().Type)
+			}
+
+			bc.postBatchResumeToken = pbrt
+		}
+	}
+
+	// close session if everything fits in first batch
+	if bc.id == 0 {
+		bc.closeImplicitSession()
+	}
+	return bc, nil
+}
+
+// NewEmptyBatchCursor returns a batch cursor that is empty.
+func NewEmptyBatchCursor() *BatchCursor {
+	return &BatchCursor{currentBatch: new(bsoncore.DocumentSequence)}
+}
+
+// NewLegacyBatchCursor creates a new BatchCursor for server versions 3.0 and below from the
+// provided parameters.
+//
+// TODO(GODRIVER-617): The batch parameter here should be []bsoncore.Document. Change it to this
+// once we have the new wiremessage package that uses bsoncore instead of bson.
+func NewLegacyBatchCursor(ns command.Namespace, cursorID int64, ds *bsoncore.DocumentSequence, limit int32, batchSize int32, server *topology.Server) (*BatchCursor, error) {
+	dsCount := ds.DocumentCount()
+	bc := &BatchCursor{
+		id:          cursorID,
+		server:      server,
+		namespace:   ns,
+		limit:       limit,
+		batchSize:   batchSize,
+		numReturned: int32(dsCount),
+		firstBatch:  true,
+	}
+
+	// take as many documents from the batch as needed
+	if limit != 0 && limit < int32(dsCount) {
+		for i := int32(0); i < limit; i++ {
+			_, err := ds.Next()
+			if err != nil {
+				return nil, err
+			}
+		}
+		ds.Data = ds.Data[:ds.Pos]
+		ds.ResetIterator()
+	}
+	bc.currentBatch = ds
+
+	return bc, nil
+}
+
+// ID returns the cursor ID for this batch cursor.
+func (bc *BatchCursor) ID() int64 {
+	return bc.id
+}
+
+// Next indicates if there is another batch available. Returning false does not necessarily indicate
+// that the cursor is closed. This method will return false when an empty batch is returned.
+//
+// If Next returns true, there is a valid batch of documents available. If Next returns false, there
+// is not a valid batch of documents available.
+func (bc *BatchCursor) Next(ctx context.Context) bool {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	if bc.firstBatch {
+		bc.firstBatch = false
+		return true
+	}
+
+	if bc.id == 0 || bc.server == nil {
+		return false
+	}
+
+	if bc.legacy() {
+		bc.legacyGetMore(ctx)
+	} else {
+		bc.getMore(ctx)
+	}
+
+	switch bc.currentBatch.Style {
+	case bsoncore.SequenceStyle:
+		return len(bc.currentBatch.Data) > 0
+	case bsoncore.ArrayStyle:
+		return len(bc.currentBatch.Data) > 5
+	default:
+		return false
+	}
+}
+
+// Batch will return a DocumentSequence for the current batch of documents. The returned
+// DocumentSequence is only valid until the next call to Next or Close.
+func (bc *BatchCursor) Batch() *bsoncore.DocumentSequence { return bc.currentBatch }
+
+// Server returns a pointer to the cursor's server.
+func (bc *BatchCursor) Server() driver.Server { return bc.server }
+
+// Err returns the latest error encountered.
+func (bc *BatchCursor) Err() error { return bc.err }
+
+// Close closes this batch cursor.
+func (bc *BatchCursor) Close(ctx context.Context) error {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	if bc.server == nil {
+		return nil
+	}
+
+	if bc.legacy() {
+		return bc.legacyKillCursor(ctx)
+	}
+
+	defer bc.closeImplicitSession()
+	conn, err := bc.server.ConnectionLegacy(ctx)
+	if err != nil {
+		return err
+	}
+
+	_, err = (&command.KillCursors{
+		Clock: bc.clock,
+		NS:    bc.namespace,
+		IDs:   []int64{bc.id},
+	}).RoundTrip(ctx, bc.server.SelectedDescription(), conn)
+	if err != nil {
+		_ = conn.Close() // The command response error is more important here
+		return err
+	}
+
+	bc.id = 0
+	bc.currentBatch.Data = nil
+	bc.currentBatch.Style = 0
+	bc.currentBatch.ResetIterator()
+
+	return conn.Close()
+}
+
+// PostBatchResumeToken returns the latest seen post batch resume token.
+func (bc *BatchCursor) PostBatchResumeToken() bsoncore.Document {
+	return bc.postBatchResumeToken
+}
+
+func (bc *BatchCursor) closeImplicitSession() {
+	if bc.clientSession != nil && bc.clientSession.SessionType == session.Implicit {
+		bc.clientSession.EndSession()
+	}
+}
+
+func (bc *BatchCursor) clearBatch() {
+	bc.currentBatch.Data = bc.currentBatch.Data[:0]
+}
+
+func (bc *BatchCursor) getMore(ctx context.Context) {
+	bc.clearBatch()
+	if bc.id == 0 {
+		return
+	}
+
+	conn, err := bc.server.ConnectionLegacy(ctx)
+	if err != nil {
+		bc.err = err
+		return
+	}
+
+	response, err := (&command.GetMore{
+		Clock:   bc.clock,
+		ID:      bc.id,
+		NS:      bc.namespace,
+		Opts:    bc.opts,
+		Session: bc.clientSession,
+	}).RoundTrip(ctx, bc.server.SelectedDescription(), conn)
+	if err != nil {
+		_ = conn.Close() // The command response error is more important here
+		bc.err = err
+		return
+	}
+
+	err = conn.Close()
+	if err != nil {
+		bc.err = err
+		return
+	}
+
+	id, err := response.LookupErr("cursor", "id")
+	if err != nil {
+		bc.err = err
+		return
+	}
+	var ok bool
+	bc.id, ok = id.Int64OK()
+	if !ok {
+		bc.err = fmt.Errorf("BSON Type %s is not %s", id.Type, bson.TypeInt64)
+		return
+	}
+
+	// if this is the last getMore, close the session
+	if bc.id == 0 {
+		bc.closeImplicitSession()
+	}
+
+	batch, err := response.LookupErr("cursor", "nextBatch")
+	if err != nil {
+		bc.err = err
+		return
+	}
+	var arr bson.Raw
+	arr, ok = batch.ArrayOK()
+	if !ok {
+		bc.err = fmt.Errorf("BSON Type %s is not %s", batch.Type, bson.TypeArray)
+		return
+	}
+	bc.currentBatch.Style = bsoncore.ArrayStyle
+	bc.currentBatch.Data = arr
+	bc.currentBatch.ResetIterator()
+
+	pbrt, err := response.LookupErr("cursor", "postBatchResumeToken")
+	if err != nil {
+		// don't set bc.err because post batch resume token is only returned on server versions >= 4.0.7
+		return
+	}
+
+	pbrtDoc, ok := pbrt.DocumentOK()
+	if !ok {
+		bc.err = fmt.Errorf("expected BSON type for post batch resume token to be EmbeddedDocument but got %s", pbrt.Type)
+		return
+	}
+
+	bc.postBatchResumeToken = bsoncore.Document(pbrtDoc)
+}
+
+func (bc *BatchCursor) legacy() bool {
+	return bc.server.Description().WireVersion == nil || bc.server.Description().WireVersion.Max < 4
+}
+
+func (bc *BatchCursor) legacyKillCursor(ctx context.Context) error {
+	conn, err := bc.server.ConnectionLegacy(ctx)
+	if err != nil {
+		return err
+	}
+
+	kc := wiremessage.KillCursors{
+		NumberOfCursorIDs: 1,
+		CursorIDs:         []int64{bc.id},
+		CollectionName:    bc.namespace.Collection,
+		DatabaseName:      bc.namespace.DB,
+	}
+
+	err = conn.WriteWireMessage(ctx, kc)
+	if err != nil {
+		_ = conn.Close()
+		return err
+	}
+
+	err = conn.Close() // no reply from OP_KILL_CURSORS
+	if err != nil {
+		return err
+	}
+
+	bc.id = 0
+	bc.clearBatch()
+	return nil
+}
+
+func (bc *BatchCursor) legacyGetMore(ctx context.Context) {
+	bc.clearBatch()
+	if bc.id == 0 {
+		return
+	}
+
+	conn, err := bc.server.ConnectionLegacy(ctx)
+	if err != nil {
+		bc.err = err
+		return
+	}
+
+	numToReturn := bc.batchSize
+	if bc.limit != 0 && bc.numReturned+bc.batchSize > bc.limit {
+		numToReturn = bc.limit - bc.numReturned
+		if numToReturn <= 0 {
+			err = bc.Close(ctx)
+			if err != nil {
+				bc.err = err
+			}
+			return
+		}
+	}
+	gm := wiremessage.GetMore{
+		FullCollectionName: bc.namespace.DB + "." + bc.namespace.Collection,
+		CursorID:           bc.id,
+		NumberToReturn:     numToReturn,
+	}
+
+	err = conn.WriteWireMessage(ctx, gm)
+	if err != nil {
+		_ = conn.Close()
+		bc.err = err
+		return
+	}
+
+	response, err := conn.ReadWireMessage(ctx)
+	if err != nil {
+		_ = conn.Close()
+		bc.err = err
+		return
+	}
+
+	err = conn.Close()
+	if err != nil {
+		bc.err = err
+		return
+	}
+
+	reply, ok := response.(wiremessage.Reply)
+	if !ok {
+		bc.err = errors.New("did not receive OP_REPLY response")
+		return
+	}
+
+	err = validateGetMoreReply(reply)
+	if err != nil {
+		bc.err = err
+		return
+	}
+
+	bc.id = reply.CursorID
+	bc.numReturned += reply.NumberReturned
+	if bc.limit != 0 && bc.numReturned >= bc.limit {
+		err = bc.Close(ctx)
+		if err != nil {
+			bc.err = err
+			return
+		}
+	}
+
+	// TODO(GODRIVER-617): When the wiremessage package is updated, we should ensure we can get all
+	// of the documents as a single slice instead of having to reslice.
+	bc.currentBatch.Style = bsoncore.SequenceStyle
+	for _, doc := range reply.Documents {
+		bc.currentBatch.Data = append(bc.currentBatch.Data, doc...)
+	}
+	bc.currentBatch.ResetIterator()
+}
+
+func validateGetMoreReply(reply wiremessage.Reply) error {
+	if int(reply.NumberReturned) != len(reply.Documents) {
+		return command.NewCommandResponseError("malformed OP_REPLY: NumberReturned does not match number of returned documents", nil)
+	}
+
+	if reply.ResponseFlags&wiremessage.CursorNotFound == wiremessage.CursorNotFound {
+		return command.QueryFailureError{
+			Message: "query failure - cursor not found",
+		}
+	}
+	if reply.ResponseFlags&wiremessage.QueryFailure == wiremessage.QueryFailure {
+		return command.QueryFailureError{
+			Message:  "query failure",
+			Response: reply.Documents[0],
+		}
+	}
+
+	return nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/bulk_write.go

@@ -0,0 +1,669 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// BulkWriteError is an error from one operation in a bulk write.
+type BulkWriteError struct {
+	result.WriteError
+	Model WriteModel
+}
+
+// BulkWriteException is a collection of errors returned by a bulk write operation.
+type BulkWriteException struct {
+	WriteConcernError *result.WriteConcernError
+	WriteErrors       []BulkWriteError
+}
+
+func (BulkWriteException) Error() string {
+	return ""
+}
+
+type bulkWriteBatch struct {
+	models   []WriteModel
+	canRetry bool
+}
+
+// BulkWrite handles the full dispatch cycle for a bulk write operation.
+func BulkWrite(
+	ctx context.Context,
+	ns command.Namespace,
+	models []WriteModel,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	sess *session.Client,
+	writeConcern *writeconcern.WriteConcern,
+	clock *session.ClusterClock,
+	registry *bsoncodec.Registry,
+	opts ...*options.BulkWriteOptions,
+) (result.BulkWrite, error) {
+	if sess != nil && sess.PinnedServer != nil {
+		selector = sess.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.BulkWrite{}, err
+	}
+
+	err = verifyOptions(models, ss)
+	if err != nil {
+		return result.BulkWrite{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if sess == nil && topo.SupportsSessions() {
+		sess, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.BulkWrite{}, err
+		}
+
+		defer sess.EndSession()
+	}
+
+	bwOpts := options.MergeBulkWriteOptions(opts...)
+
+	ordered := *bwOpts.Ordered
+
+	batches := createBatches(models, ordered)
+	bwRes := result.BulkWrite{
+		UpsertedIDs: make(map[int64]interface{}),
+	}
+	bwErr := BulkWriteException{
+		WriteErrors: make([]BulkWriteError, 0),
+	}
+
+	var lastErr error
+	var opIndex int64 // the operation index for the upsertedIDs map
+	continueOnError := !ordered
+	for _, batch := range batches {
+		if len(batch.models) == 0 {
+			continue
+		}
+
+		bypassDocValidation := bwOpts.BypassDocumentValidation
+		if bypassDocValidation != nil && !*bypassDocValidation {
+			bypassDocValidation = nil
+		}
+
+		batchRes, batchErr, err := runBatch(ctx, ns, topo, selector, ss, sess, clock, writeConcern, retryWrite,
+			bypassDocValidation, continueOnError, batch, registry)
+
+		mergeResults(&bwRes, batchRes, opIndex)
+		bwErr.WriteConcernError = batchErr.WriteConcernError
+		for i := range batchErr.WriteErrors {
+			batchErr.WriteErrors[i].Index = batchErr.WriteErrors[i].Index + int(opIndex)
+		}
+		bwErr.WriteErrors = append(bwErr.WriteErrors, batchErr.WriteErrors...)
+
+		if !continueOnError && (err != nil || len(batchErr.WriteErrors) > 0 || batchErr.WriteConcernError != nil) {
+			if err != nil {
+				return bwRes, err
+			}
+
+			return bwRes, bwErr
+		}
+
+		if err != nil {
+			lastErr = err
+		}
+
+		opIndex += int64(len(batch.models))
+	}
+
+	bwRes.MatchedCount -= bwRes.UpsertedCount
+	if lastErr != nil {
+		return bwRes, lastErr
+	}
+	if len(bwErr.WriteErrors) > 0 || bwErr.WriteConcernError != nil {
+		return bwRes, bwErr
+	}
+	return bwRes, nil
+}
+
+func runBatch(
+	ctx context.Context,
+	ns command.Namespace,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	ss *topology.SelectedServer,
+	sess *session.Client,
+	clock *session.ClusterClock,
+	wc *writeconcern.WriteConcern,
+	retryWrite bool,
+	bypassDocValidation *bool,
+	continueOnError bool,
+	batch bulkWriteBatch,
+	registry *bsoncodec.Registry,
+) (result.BulkWrite, BulkWriteException, error) {
+	batchRes := result.BulkWrite{
+		UpsertedIDs: make(map[int64]interface{}),
+	}
+	batchErr := BulkWriteException{}
+
+	var writeErrors []result.WriteError
+	switch batch.models[0].(type) {
+	case InsertOneModel:
+		res, err := runInsert(ctx, ns, topo, selector, ss, sess, clock, wc, retryWrite, batch, bypassDocValidation,
+			continueOnError, registry)
+		if err != nil {
+			return result.BulkWrite{}, BulkWriteException{}, err
+		}
+
+		batchRes.InsertedCount = int64(res.N)
+		writeErrors = res.WriteErrors
+		batchErr.WriteConcernError = res.WriteConcernError
+	case DeleteOneModel, DeleteManyModel:
+		res, err := runDelete(ctx, ns, topo, selector, ss, sess, clock, wc, retryWrite, batch, continueOnError, registry)
+		if err != nil {
+			return result.BulkWrite{}, BulkWriteException{}, err
+		}
+
+		batchRes.DeletedCount = int64(res.N)
+		writeErrors = res.WriteErrors
+		batchErr.WriteConcernError = res.WriteConcernError
+	case ReplaceOneModel, UpdateOneModel, UpdateManyModel:
+		res, err := runUpdate(ctx, ns, topo, selector, ss, sess, clock, wc, retryWrite, batch, bypassDocValidation,
+			continueOnError, registry)
+		if err != nil {
+			return result.BulkWrite{}, BulkWriteException{}, err
+		}
+
+		batchRes.MatchedCount = res.MatchedCount
+		batchRes.ModifiedCount = res.ModifiedCount
+		batchRes.UpsertedCount = int64(len(res.Upserted))
+		writeErrors = res.WriteErrors
+		batchErr.WriteConcernError = res.WriteConcernError
+		for _, upsert := range res.Upserted {
+			batchRes.UpsertedIDs[upsert.Index] = upsert.ID
+		}
+	}
+
+	batchErr.WriteErrors = make([]BulkWriteError, 0, len(writeErrors))
+	for _, we := range writeErrors {
+		batchErr.WriteErrors = append(batchErr.WriteErrors, BulkWriteError{
+			WriteError: we,
+			Model:      batch.models[0],
+		})
+	}
+
+	return batchRes, batchErr, nil
+}
+
+func runInsert(
+	ctx context.Context,
+	ns command.Namespace,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	ss *topology.SelectedServer,
+	sess *session.Client,
+	clock *session.ClusterClock,
+	wc *writeconcern.WriteConcern,
+	retryWrite bool,
+	batch bulkWriteBatch,
+	bypassDocValidation *bool,
+	continueOnError bool,
+	registry *bsoncodec.Registry,
+) (result.Insert, error) {
+	docs := make([]bsonx.Doc, len(batch.models))
+	var i int
+	for _, model := range batch.models {
+		converted := model.(InsertOneModel)
+		doc, err := interfaceToDocument(converted.Document, registry)
+		if err != nil {
+			return result.Insert{}, err
+		}
+
+		docs[i] = doc
+		i++
+	}
+
+	cmd := command.Insert{
+		ContinueOnError: continueOnError,
+		NS:              ns,
+		Docs:            docs,
+		Session:         sess,
+		Clock:           clock,
+		WriteConcern:    wc,
+	}
+
+	cmd.Opts = []bsonx.Elem{{"ordered", bsonx.Boolean(!continueOnError)}}
+	if bypassDocValidation != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*bypassDocValidation)})
+	}
+
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite || !batch.canRetry {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false
+		}
+		return insert(ctx, &cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, origErr := insert(ctx, &cmd, ss, nil)
+	if shouldRetry(origErr, res.WriteConcernError) {
+		newServer, err := topo.SelectServerLegacy(ctx, selector)
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, origErr
+		}
+
+		return insert(ctx, &cmd, newServer, origErr)
+	}
+
+	return res, origErr
+}
+
+func runDelete(
+	ctx context.Context,
+	ns command.Namespace,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	ss *topology.SelectedServer,
+	sess *session.Client,
+	clock *session.ClusterClock,
+	wc *writeconcern.WriteConcern,
+	retryWrite bool,
+	batch bulkWriteBatch,
+	continueOnError bool,
+	registry *bsoncodec.Registry,
+) (result.Delete, error) {
+	docs := make([]bsonx.Doc, len(batch.models))
+	var i int
+
+	for _, model := range batch.models {
+		var doc bsonx.Doc
+		var err error
+
+		if dom, ok := model.(DeleteOneModel); ok {
+			doc, err = createDeleteDoc(dom.Filter, dom.Collation, false, registry)
+		} else if dmm, ok := model.(DeleteManyModel); ok {
+			doc, err = createDeleteDoc(dmm.Filter, dmm.Collation, true, registry)
+		}
+
+		if err != nil {
+			return result.Delete{}, err
+		}
+
+		docs[i] = doc
+		i++
+	}
+
+	cmd := command.Delete{
+		ContinueOnError: continueOnError,
+		NS:              ns,
+		Deletes:         docs,
+		Session:         sess,
+		Clock:           clock,
+		WriteConcern:    wc,
+	}
+	cmd.Opts = []bsonx.Elem{{"ordered", bsonx.Boolean(!continueOnError)}}
+
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite || !batch.canRetry {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false
+		}
+		return delete(ctx, &cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, origErr := delete(ctx, &cmd, ss, nil)
+	if shouldRetry(origErr, res.WriteConcernError) {
+		newServer, err := topo.SelectServerLegacy(ctx, selector)
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, origErr
+		}
+
+		return delete(ctx, &cmd, newServer, origErr)
+	}
+
+	return res, origErr
+}
+
+func runUpdate(
+	ctx context.Context,
+	ns command.Namespace,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	ss *topology.SelectedServer,
+	sess *session.Client,
+	clock *session.ClusterClock,
+	wc *writeconcern.WriteConcern,
+	retryWrite bool,
+	batch bulkWriteBatch,
+	bypassDocValidation *bool,
+	continueOnError bool,
+	registry *bsoncodec.Registry,
+) (result.Update, error) {
+	docs := make([]bsonx.Doc, len(batch.models))
+
+	for i, model := range batch.models {
+		var doc bsonx.Doc
+		var err error
+
+		if rom, ok := model.(ReplaceOneModel); ok {
+			doc, err = createUpdateDoc(rom.Filter, rom.Replacement, options.ArrayFilters{}, false, rom.UpdateModel, false,
+				registry)
+		} else if uom, ok := model.(UpdateOneModel); ok {
+			doc, err = createUpdateDoc(uom.Filter, uom.Update, uom.ArrayFilters, uom.ArrayFiltersSet, uom.UpdateModel, false,
+				registry)
+		} else if umm, ok := model.(UpdateManyModel); ok {
+			doc, err = createUpdateDoc(umm.Filter, umm.Update, umm.ArrayFilters, umm.ArrayFiltersSet, umm.UpdateModel, true,
+				registry)
+		}
+
+		if err != nil {
+			return result.Update{}, err
+		}
+
+		docs[i] = doc
+	}
+
+	cmd := command.Update{
+		ContinueOnError: continueOnError,
+		NS:              ns,
+		Docs:            docs,
+		Session:         sess,
+		Clock:           clock,
+		WriteConcern:    wc,
+	}
+
+	cmd.Opts = []bsonx.Elem{{"ordered", bsonx.Boolean(!continueOnError)}}
+	if bypassDocValidation != nil {
+		// TODO this is temporary!
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*bypassDocValidation)})
+		//cmd.Opts = []option.UpdateOptioner{option.OptBypassDocumentValidation(bypassDocValidation)}
+	}
+
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite || !batch.canRetry {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false
+		}
+		return update(ctx, &cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, origErr := update(ctx, &cmd, ss, nil)
+	if shouldRetry(origErr, res.WriteConcernError) {
+		newServer, err := topo.SelectServerLegacy(ctx, selector)
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, origErr
+		}
+
+		return update(ctx, &cmd, newServer, origErr)
+	}
+
+	return res, origErr
+}
+
+func verifyOptions(models []WriteModel, ss *topology.SelectedServer) error {
+	maxVersion := ss.Description().WireVersion.Max
+	// 3.4 is wire version 5
+	// 3.6 is wire version 6
+
+	for _, model := range models {
+		var collationSet bool
+		var afSet bool // arrayFilters
+
+		switch converted := model.(type) {
+		case DeleteOneModel:
+			collationSet = converted.Collation != nil
+		case DeleteManyModel:
+			collationSet = converted.Collation != nil
+		case ReplaceOneModel:
+			collationSet = converted.Collation != nil
+		case UpdateOneModel:
+			afSet = converted.ArrayFiltersSet
+			collationSet = converted.Collation != nil
+		case UpdateManyModel:
+			afSet = converted.ArrayFiltersSet
+			collationSet = converted.Collation != nil
+		}
+
+		if afSet && maxVersion < 6 {
+			return ErrArrayFilters
+		}
+
+		if collationSet && maxVersion < 5 {
+			return ErrCollation
+		}
+	}
+
+	return nil
+}
+
+func createBatches(models []WriteModel, ordered bool) []bulkWriteBatch {
+	if ordered {
+		return createOrderedBatches(models)
+	}
+
+	batches := make([]bulkWriteBatch, 3)
+	var i int
+	for i = 0; i < 3; i++ {
+		batches[i].canRetry = true
+	}
+
+	var numBatches int // number of batches used. can't use len(batches) because it's set to 3
+	insertInd := -1
+	updateInd := -1
+	deleteInd := -1
+
+	for _, model := range models {
+		switch converted := model.(type) {
+		case InsertOneModel:
+			if insertInd == -1 {
+				// this is the first InsertOneModel
+				insertInd = numBatches
+				numBatches++
+			}
+
+			batches[insertInd].models = append(batches[insertInd].models, model)
+		case DeleteOneModel, DeleteManyModel:
+			if deleteInd == -1 {
+				deleteInd = numBatches
+				numBatches++
+			}
+
+			batches[deleteInd].models = append(batches[deleteInd].models, model)
+			if _, ok := converted.(DeleteManyModel); ok {
+				batches[deleteInd].canRetry = false
+			}
+		case ReplaceOneModel, UpdateOneModel, UpdateManyModel:
+			if updateInd == -1 {
+				updateInd = numBatches
+				numBatches++
+			}
+
+			batches[updateInd].models = append(batches[updateInd].models, model)
+			if _, ok := converted.(UpdateManyModel); ok {
+				batches[updateInd].canRetry = false
+			}
+		}
+	}
+
+	return batches
+}
+
+func createOrderedBatches(models []WriteModel) []bulkWriteBatch {
+	var batches []bulkWriteBatch
+	var prevKind command.WriteCommandKind = -1
+	i := -1 // batch index
+
+	for _, model := range models {
+		var createNewBatch bool
+		var canRetry bool
+		var newKind command.WriteCommandKind
+
+		switch model.(type) {
+		case InsertOneModel:
+			createNewBatch = prevKind != command.InsertCommand
+			canRetry = true
+			newKind = command.InsertCommand
+		case DeleteOneModel:
+			createNewBatch = prevKind != command.DeleteCommand
+			canRetry = true
+			newKind = command.DeleteCommand
+		case DeleteManyModel:
+			createNewBatch = prevKind != command.DeleteCommand
+			newKind = command.DeleteCommand
+		case ReplaceOneModel, UpdateOneModel:
+			createNewBatch = prevKind != command.UpdateCommand
+			canRetry = true
+			newKind = command.UpdateCommand
+		case UpdateManyModel:
+			createNewBatch = prevKind != command.UpdateCommand
+			newKind = command.UpdateCommand
+		}
+
+		if createNewBatch {
+			batches = append(batches, bulkWriteBatch{
+				models:   []WriteModel{model},
+				canRetry: canRetry,
+			})
+			i++
+		} else {
+			batches[i].models = append(batches[i].models, model)
+			if !canRetry {
+				batches[i].canRetry = false // don't make it true if it was already false
+			}
+		}
+
+		prevKind = newKind
+	}
+
+	return batches
+}
+
+func shouldRetry(cmdErr error, wcErr *result.WriteConcernError) bool {
+	if cerr, ok := cmdErr.(command.Error); ok && cerr.Retryable() ||
+		wcErr != nil && command.IsWriteConcernErrorRetryable(wcErr) {
+		return true
+	}
+
+	return false
+}
+
+func createUpdateDoc(
+	filter interface{},
+	update interface{},
+	arrayFilters options.ArrayFilters,
+	arrayFiltersSet bool,
+	updateModel UpdateModel,
+	multi bool,
+	registry *bsoncodec.Registry,
+) (bsonx.Doc, error) {
+	f, err := interfaceToDocument(filter, registry)
+	if err != nil {
+		return nil, err
+	}
+
+	u, err := interfaceToDocument(update, registry)
+	if err != nil {
+		return nil, err
+	}
+
+	doc := bsonx.Doc{
+		{"q", bsonx.Document(f)},
+		{"u", bsonx.Document(u)},
+		{"multi", bsonx.Boolean(multi)},
+	}
+
+	if arrayFiltersSet {
+		filters, err := arrayFilters.ToArray()
+		if err != nil {
+			return nil, err
+		}
+		arr := make(bsonx.Arr, 0, len(filters))
+		for _, filter := range filters {
+			doc, err := bsonx.ReadDoc(filter)
+			if err != nil {
+				return nil, err
+			}
+			arr = append(arr, bsonx.Document(doc))
+		}
+		doc = append(doc, bsonx.Elem{"arrayFilters", bsonx.Array(arr)})
+	}
+
+	if updateModel.Collation != nil {
+		collDoc, err := bsonx.ReadDoc(updateModel.Collation.ToDocument())
+		if err != nil {
+			return nil, err
+		}
+		doc = append(doc, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+
+	if updateModel.UpsertSet {
+		doc = append(doc, bsonx.Elem{"upsert", bsonx.Boolean(updateModel.Upsert)})
+	}
+
+	return doc, nil
+}
+
+func createDeleteDoc(
+	filter interface{},
+	collation *options.Collation,
+	many bool,
+	registry *bsoncodec.Registry,
+) (bsonx.Doc, error) {
+	f, err := interfaceToDocument(filter, registry)
+	if err != nil {
+		return nil, err
+	}
+
+	var limit int32 = 1
+	if many {
+		limit = 0
+	}
+
+	doc := bsonx.Doc{
+		{"q", bsonx.Document(f)},
+		{"limit", bsonx.Int32(limit)},
+	}
+
+	if collation != nil {
+		collDoc, err := bsonx.ReadDoc(collation.ToDocument())
+		if err != nil {
+			return nil, err
+		}
+		doc = append(doc, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+
+	return doc, nil
+}
+
+func mergeResults(aggResult *result.BulkWrite, newResult result.BulkWrite, opIndex int64) {
+	aggResult.InsertedCount += newResult.InsertedCount
+	aggResult.MatchedCount += newResult.MatchedCount
+	aggResult.ModifiedCount += newResult.ModifiedCount
+	aggResult.DeletedCount += newResult.DeletedCount
+	aggResult.UpsertedCount += newResult.UpsertedCount
+
+	for index, upsertID := range newResult.UpsertedIDs {
+		aggResult.UpsertedIDs[index+opIndex] = upsertID
+	}
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/commit_transaction.go

@@ -0,0 +1,120 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// CommitTransaction handles the full cycle dispatch and execution of committing a transaction
+// against the provided topology.
+func CommitTransaction(
+	ctx context.Context,
+	cmd command.CommitTransaction,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+) (result.TransactionResult, error) {
+	res, err := commitTransaction(ctx, cmd, topo, selector, nil)
+
+	// Apply majority write concern for retries
+	currWC := cmd.Session.CurrentWc
+	newTimeout := 10 * time.Second
+	if currWC != nil && currWC.GetWTimeout() != 0 {
+		newTimeout = currWC.GetWTimeout()
+	}
+	cmd.Session.CurrentWc = currWC.WithOptions(writeconcern.WMajority(), writeconcern.WTimeout(newTimeout))
+
+	if cerr, ok := err.(command.Error); ok && err != nil {
+		// Retry if appropriate
+		if cerr.Retryable() {
+			res, err = commitTransaction(ctx, cmd, topo, selector, cerr)
+			if cerr2, ok := err.(command.Error); ok && err != nil {
+				// Retry failures also get label
+				cerr2.Labels = append(cerr2.Labels, command.UnknownTransactionCommitResult)
+			} else if err != nil {
+				err = command.Error{Message: err.Error(), Labels: []string{command.UnknownTransactionCommitResult}}
+			}
+		}
+	}
+	return res, err
+}
+
+func commitTransaction(
+	ctx context.Context,
+	cmd command.CommitTransaction,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	oldErr error,
+) (result.TransactionResult, error) {
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		// If retrying server selection, return the original error if it fails
+		if oldErr != nil {
+			return result.TransactionResult{}, oldErr
+		}
+		return result.TransactionResult{}, err
+	}
+
+	desc := ss.Description()
+
+	if oldErr != nil && (!topo.SupportsSessions() || !description.SessionsSupported(desc.WireVersion)) {
+		// Assuming we are retrying (oldErr != nil),
+		// if server doesn't support retryable writes, return the original error
+		// Conditions for retry write support are the same as that of sessions
+		return result.TransactionResult{}, oldErr
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.TransactionResult{}, oldErr
+		}
+		return result.TransactionResult{}, err
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+
+	// Add UnknownCommitTransaction Error label where appropriate
+	if err != nil {
+		var newLabels []string
+		if cerr, ok := err.(command.Error); ok {
+			// Replace the label TransientTransactionError with UnknownTransactionCommitResult
+			// if network error, write concern shutdown, or write concern failed errors
+			hasUnknownCommitErr := false
+			for _, label := range cerr.Labels {
+				if label == command.NetworkError {
+					hasUnknownCommitErr = true
+					break
+				}
+			}
+
+			// network error, retryable error, or write concern fail/timeout (64) get the unknown label
+			if hasUnknownCommitErr || cerr.Retryable() || cerr.Code == 64 {
+				for _, label := range cerr.Labels {
+					if label != command.TransientTransactionError {
+						newLabels = append(newLabels, label)
+					}
+				}
+				newLabels = append(newLabels, command.UnknownTransactionCommitResult)
+				cerr.Labels = newLabels
+			}
+			err = cerr
+		}
+	}
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/count.go

@@ -0,0 +1,97 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// Count handles the full cycle dispatch and execution of a count command against the provided
+// topology.
+func Count(
+	ctx context.Context,
+	cmd command.Count,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	registry *bsoncodec.Registry,
+	opts ...*options.CountOptions,
+) (int64, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return 0, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer conn.Close()
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return 0, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return 0, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	countOpts := options.MergeCountOptions(opts...)
+
+	if countOpts.Limit != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"limit", bsonx.Int64(*countOpts.Limit)})
+	}
+	if countOpts.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{
+			"maxTimeMS", bsonx.Int64(int64(*countOpts.MaxTime / time.Millisecond)),
+		})
+	}
+	if countOpts.Skip != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"skip", bsonx.Int64(*countOpts.Skip)})
+	}
+	if countOpts.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return 0, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(countOpts.Collation.ToDocument())
+		if err != nil {
+			return 0, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if countOpts.Hint != nil {
+		hintElem, err := interfaceToElement("hint", countOpts.Hint, registry)
+		if err != nil {
+			return 0, err
+		}
+
+		cmd.Opts = append(cmd.Opts, hintElem)
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/count_documents.go

@@ -0,0 +1,94 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// CountDocuments handles the full cycle dispatch and execution of a countDocuments command against the provided
+// topology.
+func CountDocuments(
+	ctx context.Context,
+	cmd command.CountDocuments,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	registry *bsoncodec.Registry,
+	opts ...*options.CountOptions,
+) (int64, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return 0, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer conn.Close()
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return 0, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return 0, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	countOpts := options.MergeCountOptions(opts...)
+
+	// ignore Skip and Limit because we already have these options in the pipeline
+	if countOpts.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{
+			"maxTimeMS", bsonx.Int64(int64(*countOpts.MaxTime / time.Millisecond)),
+		})
+	}
+	if countOpts.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return 0, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(countOpts.Collation.ToDocument())
+		if err != nil {
+			return 0, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if countOpts.Hint != nil {
+		hintElem, err := interfaceToElement("hint", countOpts.Hint, registry)
+		if err != nil {
+			return 0, err
+		}
+
+		cmd.Opts = append(cmd.Opts, hintElem)
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/create_indexes.go

@@ -0,0 +1,77 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// CreateIndexes handles the full cycle dispatch and execution of a createIndexes
+// command against the provided topology.
+func CreateIndexes(
+	ctx context.Context,
+	cmd command.CreateIndexes,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.CreateIndexesOptions,
+) (result.CreateIndexes, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.CreateIndexes{}, err
+	}
+
+	desc := ss.Description()
+	if desc.WireVersion.Max < 5 && hasCollation(cmd) {
+		return result.CreateIndexes{}, ErrCollation
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return result.CreateIndexes{}, err
+	}
+	defer conn.Close()
+
+	cio := options.MergeCreateIndexesOptions(opts...)
+	if cio.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*cio.MaxTime / time.Millisecond))})
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.CreateIndexes{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}
+
+func hasCollation(cmd command.CreateIndexes) bool {
+	for _, ind := range cmd.Indexes {
+		if _, err := ind.Document().LookupErr("collation"); err == nil {
+			return true
+		}
+	}
+
+	return false
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/delete.go

@@ -0,0 +1,124 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// Delete handles the full cycle dispatch and execution of a delete command against the provided
+// topology.
+func Delete(
+	ctx context.Context,
+	cmd command.Delete,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	opts ...*options.DeleteOptions,
+) (result.Delete, error) {
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.Delete{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() && writeconcern.AckWrite(cmd.WriteConcern) {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.Delete{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	deleteOpts := options.MergeDeleteOptions(opts...)
+	if deleteOpts.Collation != nil {
+		if ss.Description().WireVersion.Max < 5 {
+			return result.Delete{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(deleteOpts.Collation.ToDocument())
+		if err != nil {
+			return result.Delete{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return delete(ctx, &cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := delete(ctx, &cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return delete(ctx, &cmd, ss, cerr)
+	}
+	return res, originalErr
+}
+
+func delete(
+	ctx context.Context,
+	cmd *command.Delete,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.Delete, error) {
+	desc := ss.Description()
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.Delete{}, oldErr
+		}
+		return result.Delete{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.Delete{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/delete_indexes.go

@@ -0,0 +1,62 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// DropIndexes handles the full cycle dispatch and execution of a dropIndexes
+// command against the provided topology.
+func DropIndexes(
+	ctx context.Context,
+	cmd command.DropIndexes,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.DropIndexesOptions,
+) (bson.Raw, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	dio := options.MergeDropIndexesOptions(opts...)
+	if dio.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*dio.MaxTime / time.Millisecond))})
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/dispatch.go

@@ -0,0 +1,67 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy // import "go.mongodb.org/mongo-driver/x/mongo/driverlegacy"
+
+import (
+	"errors"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+)
+
+// ErrCollation is caused if a collation is given for an invalid server version.
+var ErrCollation = errors.New("collation cannot be set for server versions < 3.4")
+
+// ErrArrayFilters is caused if array filters are given for an invalid server version.
+var ErrArrayFilters = errors.New("array filters cannot be set for server versions < 3.6")
+
+func interfaceToDocument(val interface{}, registry *bsoncodec.Registry) (bsonx.Doc, error) {
+	if val == nil {
+		return bsonx.Doc{}, nil
+	}
+
+	if registry == nil {
+		registry = bson.DefaultRegistry
+	}
+
+	if bs, ok := val.([]byte); ok {
+		// Slight optimization so we'll just use MarshalBSON and not go through the codec machinery.
+		val = bson.Raw(bs)
+	}
+
+	// TODO(skriptble): Use a pool of these instead.
+	buf := make([]byte, 0, 256)
+	b, err := bson.MarshalAppendWithRegistry(registry, buf, val)
+	if err != nil {
+		return nil, err
+	}
+	return bsonx.ReadDoc(b)
+}
+
+func interfaceToElement(key string, i interface{}, registry *bsoncodec.Registry) (bsonx.Elem, error) {
+	switch conv := i.(type) {
+	case string:
+		return bsonx.Elem{key, bsonx.String(conv)}, nil
+	case bsonx.Doc:
+		return bsonx.Elem{key, bsonx.Document(conv)}, nil
+	default:
+		doc, err := interfaceToDocument(i, registry)
+		if err != nil {
+			return bsonx.Elem{}, err
+		}
+
+		return bsonx.Elem{key, bsonx.Document(doc)}, nil
+	}
+}
+
+func closeImplicitSession(sess *session.Client) {
+	if sess != nil && sess.SessionType == session.Implicit {
+		sess.EndSession()
+	}
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/distinct.go

@@ -0,0 +1,84 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// Distinct handles the full cycle dispatch and execution of a distinct command against the provided
+// topology.
+func Distinct(
+	ctx context.Context,
+	cmd command.Distinct,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.DistinctOptions,
+) (result.Distinct, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.Distinct{}, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return result.Distinct{}, err
+	}
+	defer conn.Close()
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return result.Distinct{}, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.Distinct{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	distinctOpts := options.MergeDistinctOptions(opts...)
+
+	if distinctOpts.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{
+			"maxTimeMS", bsonx.Int64(int64(*distinctOpts.MaxTime / time.Millisecond)),
+		})
+	}
+	if distinctOpts.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return result.Distinct{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(distinctOpts.Collation.ToDocument())
+		if err != nil {
+			return result.Distinct{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/drop_collection.go

@@ -0,0 +1,52 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// DropCollection handles the full cycle dispatch and execution of a dropCollection
+// command against the provided topology.
+func DropCollection(
+	ctx context.Context,
+	cmd command.DropCollection,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+) (bson.Raw, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/drop_database.go

@@ -0,0 +1,52 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// DropDatabase handles the full cycle dispatch and execution of a dropDatabase
+// command against the provided topology.
+func DropDatabase(
+	ctx context.Context,
+	cmd command.DropDatabase,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+) (bson.Raw, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/end_sessions.go

@@ -0,0 +1,40 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// EndSessions handles the full cycle dispatch and execution of an endSessions command against the provided
+// topology.
+func EndSessions(
+	ctx context.Context,
+	cmd command.EndSessions,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+) ([]result.EndSessions, []error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, []error{err}
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, []error{err}
+	}
+	defer conn.Close()
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/find.go

@@ -0,0 +1,538 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"errors"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/mongo/readpref"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/connection"
+	"go.mongodb.org/mongo-driver/x/network/wiremessage"
+)
+
+// Find handles the full cycle dispatch and execution of a find command against the provided
+// topology.
+func Find(
+	ctx context.Context,
+	cmd command.Find,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	registry *bsoncodec.Registry,
+	opts ...*options.FindOptions,
+) (*BatchCursor, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	if desc.WireVersion.Max < 4 {
+		return legacyFind(ctx, cmd, registry, ss, conn, opts...)
+	}
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return nil, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	fo := options.MergeFindOptions(opts...)
+	if fo.AllowPartialResults != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"allowPartialResults", bsonx.Boolean(*fo.AllowPartialResults)})
+	}
+	if fo.BatchSize != nil {
+		elem := bsonx.Elem{"batchSize", bsonx.Int32(*fo.BatchSize)}
+		cmd.Opts = append(cmd.Opts, elem)
+		cmd.CursorOpts = append(cmd.CursorOpts, elem)
+
+		if fo.Limit != nil && *fo.BatchSize != 0 && *fo.Limit <= int64(*fo.BatchSize) {
+			cmd.Opts = append(cmd.Opts, bsonx.Elem{"singleBatch", bsonx.Boolean(true)})
+		}
+	}
+	if fo.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return nil, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(fo.Collation.ToDocument())
+		if err != nil {
+			return nil, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if fo.Comment != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"comment", bsonx.String(*fo.Comment)})
+	}
+	if fo.CursorType != nil {
+		switch *fo.CursorType {
+		case options.Tailable:
+			cmd.Opts = append(cmd.Opts, bsonx.Elem{"tailable", bsonx.Boolean(true)})
+		case options.TailableAwait:
+			cmd.Opts = append(cmd.Opts, bsonx.Elem{"tailable", bsonx.Boolean(true)}, bsonx.Elem{"awaitData", bsonx.Boolean(true)})
+		}
+	}
+	if fo.Hint != nil {
+		hintElem, err := interfaceToElement("hint", fo.Hint, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, hintElem)
+	}
+	if fo.Limit != nil {
+		limit := *fo.Limit
+		if limit < 0 {
+			cmd.Opts = append(cmd.Opts, bsonx.Elem{"singleBatch", bsonx.Boolean(true)})
+			limit = -1 * limit
+		}
+
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"limit", bsonx.Int64(limit)})
+	}
+	if fo.Max != nil {
+		maxElem, err := interfaceToElement("max", fo.Max, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, maxElem)
+	}
+	if fo.MaxAwaitTime != nil {
+		// Specified as maxTimeMS on the in the getMore command and not given in initial find command.
+		cmd.CursorOpts = append(cmd.CursorOpts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*fo.MaxAwaitTime / time.Millisecond))})
+	}
+	if fo.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*fo.MaxTime / time.Millisecond))})
+	}
+	if fo.Min != nil {
+		minElem, err := interfaceToElement("min", fo.Min, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, minElem)
+	}
+	if fo.NoCursorTimeout != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"noCursorTimeout", bsonx.Boolean(*fo.NoCursorTimeout)})
+	}
+	if fo.OplogReplay != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"oplogReplay", bsonx.Boolean(*fo.OplogReplay)})
+	}
+	if fo.Projection != nil {
+		projElem, err := interfaceToElement("projection", fo.Projection, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, projElem)
+	}
+	if fo.ReturnKey != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"returnKey", bsonx.Boolean(*fo.ReturnKey)})
+	}
+	if fo.ShowRecordID != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"showRecordId", bsonx.Boolean(*fo.ShowRecordID)})
+	}
+	if fo.Skip != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"skip", bsonx.Int64(*fo.Skip)})
+	}
+	if fo.Snapshot != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"snapshot", bsonx.Boolean(*fo.Snapshot)})
+	}
+	if fo.Sort != nil {
+		sortElem, err := interfaceToElement("sort", fo.Sort, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		cmd.Opts = append(cmd.Opts, sortElem)
+	}
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	if err != nil {
+		closeImplicitSession(cmd.Session)
+		return nil, err
+	}
+
+	return NewBatchCursor(bsoncore.Document(res), cmd.Session, cmd.Clock, ss.Server, cmd.CursorOpts...)
+}
+
+// legacyFind handles the dispatch and execution of a find operation against a pre-3.2 server.
+func legacyFind(
+	ctx context.Context,
+	cmd command.Find,
+	registry *bsoncodec.Registry,
+	ss *topology.SelectedServer,
+	conn connection.Connection,
+	opts ...*options.FindOptions,
+) (*BatchCursor, error) {
+	query := wiremessage.Query{
+		FullCollectionName: cmd.NS.DB + "." + cmd.NS.Collection,
+	}
+
+	fo := options.MergeFindOptions(opts...)
+	optsDoc, err := createLegacyOptionsDoc(fo, registry)
+	if err != nil {
+		return nil, err
+	}
+	if fo.Projection != nil {
+		projDoc, err := interfaceToDocument(fo.Projection, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		projRaw, err := projDoc.MarshalBSON()
+		if err != nil {
+			return nil, err
+		}
+		query.ReturnFieldsSelector = projRaw
+	}
+	if fo.Skip != nil {
+		query.NumberToSkip = int32(*fo.Skip)
+		query.SkipSet = true
+	}
+	// batch size of 1 not possible with OP_QUERY because the cursor will be closed immediately
+	if fo.BatchSize != nil && *fo.BatchSize == 1 {
+		query.NumberToReturn = 2
+	} else {
+		query.NumberToReturn = calculateNumberToReturn(fo)
+	}
+	query.Flags = calculateLegacyFlags(fo)
+
+	query.BatchSize = fo.BatchSize
+	if fo.Limit != nil {
+		i := int32(*fo.Limit)
+		query.Limit = &i
+	}
+
+	// set read preference and/or slaveOK flag
+	desc := ss.SelectedDescription()
+	if slaveOkNeeded(cmd.ReadPref, desc) {
+		query.Flags |= wiremessage.SlaveOK
+	}
+	optsDoc = addReadPref(cmd.ReadPref, desc.Server.Kind, optsDoc)
+
+	if cmd.Filter == nil {
+		cmd.Filter = bsonx.Doc{}
+	}
+
+	// filter must be wrapped in $query if other $modifiers are used
+	var queryDoc bsonx.Doc
+	if len(optsDoc) == 0 {
+		queryDoc = cmd.Filter
+	} else {
+		filterDoc := bsonx.Doc{
+			{"$query", bsonx.Document(cmd.Filter)},
+		}
+		// $query should go first
+		queryDoc = append(filterDoc, optsDoc...)
+	}
+
+	queryRaw, err := queryDoc.MarshalBSON()
+	if err != nil {
+		return nil, err
+	}
+	query.Query = queryRaw
+
+	reply, err := roundTripQuery(ctx, query, conn)
+	if err != nil {
+		return nil, err
+	}
+
+	var cursorLimit int32
+	var cursorBatchSize int32
+	if query.Limit != nil {
+		cursorLimit = int32(*query.Limit)
+		if cursorLimit < 0 {
+			cursorLimit *= -1
+		}
+	}
+	if query.BatchSize != nil {
+		cursorBatchSize = int32(*query.BatchSize)
+	}
+
+	// TODO(GODRIVER-617): When the wiremessage package is updated, we should ensure we can get all
+	// of the documents as a single slice instead of having to reslice.
+	ds := new(bsoncore.DocumentSequence)
+	ds.Style = bsoncore.SequenceStyle
+	for _, doc := range reply.Documents {
+		ds.Data = append(ds.Data, doc...)
+	}
+
+	return NewLegacyBatchCursor(cmd.NS, reply.CursorID, ds, cursorLimit, cursorBatchSize, ss.Server)
+}
+
+func createLegacyOptionsDoc(fo *options.FindOptions, registry *bsoncodec.Registry) (bsonx.Doc, error) {
+	var optsDoc bsonx.Doc
+
+	if fo.Collation != nil {
+		return nil, ErrCollation
+	}
+	if fo.Comment != nil {
+		optsDoc = append(optsDoc, bsonx.Elem{"$comment", bsonx.String(*fo.Comment)})
+	}
+	if fo.Hint != nil {
+		hintElem, err := interfaceToElement("$hint", fo.Hint, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		optsDoc = append(optsDoc, hintElem)
+	}
+	if fo.Max != nil {
+		maxElem, err := interfaceToElement("$max", fo.Max, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		optsDoc = append(optsDoc, maxElem)
+	}
+	if fo.MaxTime != nil {
+		optsDoc = append(optsDoc, bsonx.Elem{"$maxTimeMS", bsonx.Int64(int64(*fo.MaxTime / time.Millisecond))})
+	}
+	if fo.Min != nil {
+		minElem, err := interfaceToElement("$min", fo.Min, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		optsDoc = append(optsDoc, minElem)
+	}
+	if fo.ReturnKey != nil {
+		optsDoc = append(optsDoc, bsonx.Elem{"$returnKey", bsonx.Boolean(*fo.ReturnKey)})
+	}
+	if fo.ShowRecordID != nil {
+		optsDoc = append(optsDoc, bsonx.Elem{"$showDiskLoc", bsonx.Boolean(*fo.ShowRecordID)})
+	}
+	if fo.Snapshot != nil {
+		optsDoc = append(optsDoc, bsonx.Elem{"$snapshot", bsonx.Boolean(*fo.Snapshot)})
+	}
+	if fo.Sort != nil {
+		sortElem, err := interfaceToElement("$orderby", fo.Sort, registry)
+		if err != nil {
+			return nil, err
+		}
+
+		optsDoc = append(optsDoc, sortElem)
+	}
+
+	return optsDoc, nil
+}
+
+func calculateLegacyFlags(fo *options.FindOptions) wiremessage.QueryFlag {
+	var flags wiremessage.QueryFlag
+
+	if fo.AllowPartialResults != nil {
+		flags |= wiremessage.Partial
+	}
+	if fo.CursorType != nil {
+		switch *fo.CursorType {
+		case options.Tailable:
+			flags |= wiremessage.TailableCursor
+		case options.TailableAwait:
+			flags |= wiremessage.TailableCursor
+			flags |= wiremessage.AwaitData
+		}
+	}
+	if fo.NoCursorTimeout != nil {
+		flags |= wiremessage.NoCursorTimeout
+	}
+	if fo.OplogReplay != nil {
+		flags |= wiremessage.OplogReplay
+	}
+
+	return flags
+}
+
+// calculate the number to return for the first find query
+func calculateNumberToReturn(opts *options.FindOptions) int32 {
+	var numReturn int32
+	var limit int32
+	var batchSize int32
+
+	if opts.Limit != nil {
+		limit = int32(*opts.Limit)
+	}
+	if opts.BatchSize != nil {
+		batchSize = int32(*opts.BatchSize)
+	}
+
+	if limit < 0 {
+		numReturn = limit
+	} else if limit == 0 {
+		numReturn = batchSize
+	} else if limit < batchSize {
+		numReturn = limit
+	} else {
+		numReturn = batchSize
+	}
+
+	return numReturn
+}
+
+func slaveOkNeeded(rp *readpref.ReadPref, desc description.SelectedServer) bool {
+	if desc.Kind == description.Single && desc.Server.Kind != description.Mongos {
+		return true
+	}
+	if rp == nil {
+		// assume primary
+		return false
+	}
+
+	return rp.Mode() != readpref.PrimaryMode
+}
+
+func addReadPref(rp *readpref.ReadPref, kind description.ServerKind, query bsonx.Doc) bsonx.Doc {
+	if !readPrefNeeded(rp, kind) {
+		return query
+	}
+
+	doc := createReadPref(rp)
+	if doc == nil {
+		return query
+	}
+
+	return query.Append("$readPreference", bsonx.Document(doc))
+}
+
+func readPrefNeeded(rp *readpref.ReadPref, kind description.ServerKind) bool {
+	if kind != description.Mongos || rp == nil {
+		return false
+	}
+
+	// simple Primary or SecondaryPreferred is communicated via slaveOk to Mongos.
+	if rp.Mode() == readpref.PrimaryMode || rp.Mode() == readpref.SecondaryPreferredMode {
+		if _, ok := rp.MaxStaleness(); !ok && len(rp.TagSets()) == 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+func createReadPref(rp *readpref.ReadPref) bsonx.Doc {
+	if rp == nil {
+		return nil
+	}
+
+	doc := bsonx.Doc{}
+
+	switch rp.Mode() {
+	case readpref.PrimaryMode:
+		doc = append(doc, bsonx.Elem{"mode", bsonx.String("primary")})
+	case readpref.PrimaryPreferredMode:
+		doc = append(doc, bsonx.Elem{"mode", bsonx.String("primaryPreferred")})
+	case readpref.SecondaryPreferredMode:
+		doc = append(doc, bsonx.Elem{"mode", bsonx.String("secondaryPreferred")})
+	case readpref.SecondaryMode:
+		doc = append(doc, bsonx.Elem{"mode", bsonx.String("secondary")})
+	case readpref.NearestMode:
+		doc = append(doc, bsonx.Elem{"mode", bsonx.String("nearest")})
+	}
+
+	sets := make([]bsonx.Val, 0, len(rp.TagSets()))
+	for _, ts := range rp.TagSets() {
+		if len(ts) == 0 {
+			continue
+		}
+		set := bsonx.Doc{}
+		for _, t := range ts {
+			set = append(set, bsonx.Elem{t.Name, bsonx.String(t.Value)})
+		}
+		sets = append(sets, bsonx.Document(set))
+	}
+	if len(sets) > 0 {
+		doc = append(doc, bsonx.Elem{"tags", bsonx.Array(sets)})
+	}
+	if d, ok := rp.MaxStaleness(); ok {
+		doc = append(doc, bsonx.Elem{"maxStalenessSeconds", bsonx.Int32(int32(d.Seconds()))})
+	}
+
+	return doc
+}
+
+func roundTripQuery(ctx context.Context, query wiremessage.Query, conn connection.Connection) (wiremessage.Reply, error) {
+	err := conn.WriteWireMessage(ctx, query)
+	if err != nil {
+		if _, ok := err.(command.Error); ok {
+			return wiremessage.Reply{}, err
+		}
+		return wiremessage.Reply{}, command.Error{
+			Message: err.Error(),
+			Labels:  []string{command.NetworkError},
+		}
+	}
+
+	wm, err := conn.ReadWireMessage(ctx)
+	if err != nil {
+		if _, ok := err.(command.Error); ok {
+			return wiremessage.Reply{}, err
+		}
+		// Connection errors are transient
+		return wiremessage.Reply{}, command.Error{
+			Message: err.Error(),
+			Labels:  []string{command.NetworkError},
+		}
+	}
+
+	reply, ok := wm.(wiremessage.Reply)
+	if !ok {
+		return wiremessage.Reply{}, errors.New("did not receive OP_REPLY response")
+	}
+
+	err = validateOpReply(reply)
+	if err != nil {
+		return wiremessage.Reply{}, err
+	}
+
+	return reply, nil
+}
+
+func validateOpReply(reply wiremessage.Reply) error {
+	if int(reply.NumberReturned) != len(reply.Documents) {
+		return command.NewCommandResponseError(command.ReplyDocumentMismatch, nil)
+	}
+
+	if reply.ResponseFlags&wiremessage.QueryFailure == wiremessage.QueryFailure {
+		return command.QueryFailureError{
+			Message:  "query failure",
+			Response: reply.Documents[0],
+		}
+	}
+
+	return nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/find_one_and_delete.go

@@ -0,0 +1,147 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// FindOneAndDelete handles the full cycle dispatch and execution of a FindOneAndDelete command against the provided
+// topology.
+func FindOneAndDelete(
+	ctx context.Context,
+	cmd command.FindOneAndDelete,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	registry *bsoncodec.Registry,
+	opts ...*options.FindOneAndDeleteOptions,
+) (result.FindAndModify, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.FindAndModify{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	do := options.MergeFindOneAndDeleteOptions(opts...)
+	if do.Collation != nil {
+		if ss.Description().WireVersion.Max < 5 {
+			return result.FindAndModify{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(do.Collation.ToDocument())
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if do.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMs", bsonx.Int64(int64(*do.MaxTime / time.Millisecond))})
+	}
+	if do.Projection != nil {
+		projElem, err := interfaceToElement("fields", do.Projection, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, projElem)
+	}
+	if do.Sort != nil {
+		sortElem, err := interfaceToElement("sort", do.Sort, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, sortElem)
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return findOneAndDelete(ctx, cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := findOneAndDelete(ctx, cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return findOneAndDelete(ctx, cmd, ss, cerr)
+	}
+
+	return res, originalErr
+}
+
+func findOneAndDelete(
+	ctx context.Context,
+	cmd command.FindOneAndDelete,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.FindAndModify, error) {
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.FindAndModify{}, oldErr
+		}
+		return result.FindAndModify{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.FindAndModify{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/find_one_and_replace.go

@@ -0,0 +1,156 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// FindOneAndReplace handles the full cycle dispatch and execution of a FindOneAndReplace command against the provided
+// topology.
+func FindOneAndReplace(
+	ctx context.Context,
+	cmd command.FindOneAndReplace,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	registry *bsoncodec.Registry,
+	opts ...*options.FindOneAndReplaceOptions,
+) (result.FindAndModify, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.FindAndModify{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	ro := options.MergeFindOneAndReplaceOptions(opts...)
+	if ro.BypassDocumentValidation != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"byapssDocumentValidation", bsonx.Boolean(*ro.BypassDocumentValidation)})
+	}
+	if ro.Collation != nil {
+		if ss.Description().WireVersion.Max < 5 {
+			return result.FindAndModify{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(ro.Collation.ToDocument())
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if ro.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*ro.MaxTime / time.Millisecond))})
+	}
+	if ro.Projection != nil {
+		maxElem, err := interfaceToElement("fields", ro.Projection, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, maxElem)
+	}
+	if ro.ReturnDocument != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"new", bsonx.Boolean(*ro.ReturnDocument == options.After)})
+	}
+	if ro.Sort != nil {
+		sortElem, err := interfaceToElement("sort", ro.Sort, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, sortElem)
+	}
+	if ro.Upsert != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"upsert", bsonx.Boolean(*ro.Upsert)})
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return findOneAndReplace(ctx, cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := findOneAndReplace(ctx, cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return findOneAndReplace(ctx, cmd, ss, cerr)
+	}
+
+	return res, originalErr
+}
+
+func findOneAndReplace(
+	ctx context.Context,
+	cmd command.FindOneAndReplace,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.FindAndModify, error) {
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.FindAndModify{}, oldErr
+		}
+		return result.FindAndModify{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.FindAndModify{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/find_one_and_update.go

@@ -0,0 +1,172 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// FindOneAndUpdate handles the full cycle dispatch and execution of a FindOneAndUpdate command against the provided
+// topology.
+func FindOneAndUpdate(
+	ctx context.Context,
+	cmd command.FindOneAndUpdate,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	registry *bsoncodec.Registry,
+	opts ...*options.FindOneAndUpdateOptions,
+) (result.FindAndModify, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.FindAndModify{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	uo := options.MergeFindOneAndUpdateOptions(opts...)
+	if uo.ArrayFilters != nil {
+		filters, err := uo.ArrayFilters.ToArray()
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		arr := make(bsonx.Arr, 0, len(filters))
+		for _, filter := range filters {
+			doc, err := bsonx.ReadDoc(filter)
+			if err != nil {
+				return result.FindAndModify{}, err
+			}
+			arr = append(arr, bsonx.Document(doc))
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"arrayFilters", bsonx.Array(arr)})
+	}
+	if uo.BypassDocumentValidation != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*uo.BypassDocumentValidation)})
+	}
+	if uo.Collation != nil {
+		if ss.Description().WireVersion.Max < 5 {
+			return result.FindAndModify{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(uo.Collation.ToDocument())
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if uo.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*uo.MaxTime / time.Millisecond))})
+	}
+	if uo.Projection != nil {
+		projElem, err := interfaceToElement("fields", uo.Projection, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, projElem)
+	}
+	if uo.ReturnDocument != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"new", bsonx.Boolean(*uo.ReturnDocument == options.After)})
+	}
+	if uo.Sort != nil {
+		sortElem, err := interfaceToElement("sort", uo.Sort, registry)
+		if err != nil {
+			return result.FindAndModify{}, err
+		}
+
+		cmd.Opts = append(cmd.Opts, sortElem)
+	}
+	if uo.Upsert != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"upsert", bsonx.Boolean(*uo.Upsert)})
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return findOneAndUpdate(ctx, cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := findOneAndUpdate(ctx, cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return findOneAndUpdate(ctx, cmd, ss, cerr)
+	}
+
+	return res, originalErr
+}
+
+func findOneAndUpdate(
+	ctx context.Context,
+	cmd command.FindOneAndUpdate,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.FindAndModify, error) {
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.FindAndModify{}, oldErr
+		}
+		return result.FindAndModify{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.FindAndModify{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/insert.go

@@ -0,0 +1,123 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// Insert handles the full cycle dispatch and execution of an insert command against the provided
+// topology.
+func Insert(
+	ctx context.Context,
+	cmd command.Insert,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	opts ...*options.InsertManyOptions,
+) (result.Insert, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.Insert{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.Insert{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	insertOpts := options.MergeInsertManyOptions(opts...)
+
+	if insertOpts.BypassDocumentValidation != nil && ss.Description().WireVersion.Includes(4) {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*insertOpts.BypassDocumentValidation)})
+	}
+	if insertOpts.Ordered != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"ordered", bsonx.Boolean(*insertOpts.Ordered)})
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return insert(ctx, &cmd, ss, nil)
+	}
+
+	// TODO figure out best place to put retry write.  Command shouldn't have to know about this field.
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := insert(ctx, &cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return insert(ctx, &cmd, ss, cerr)
+	}
+
+	return res, originalErr
+}
+
+func insert(
+	ctx context.Context,
+	cmd *command.Insert,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.Insert, error) {
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.Insert{}, oldErr
+		}
+		return result.Insert{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.Insert{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/kill_cursors.go

@@ -0,0 +1,67 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/x/network/connection"
+	"go.mongodb.org/mongo-driver/x/network/wiremessage"
+
+	"go.mongodb.org/mongo-driver/x/mongo/driver"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// KillCursors handles the full cycle dispatch and execution of an aggregate command against the provided
+// topology.
+func KillCursors(
+	ctx context.Context,
+	ns command.Namespace,
+	server driver.Server,
+	cursorID int64,
+) (result.KillCursors, error) {
+	var conn connection.Connection
+	var desc description.SelectedServer
+	var err error
+
+	if legacyServer, ok := server.(*topology.Server); ok {
+		desc = legacyServer.SelectedDescription()
+		conn, err = legacyServer.ConnectionLegacy(ctx)
+	} else if legacySs, ok := server.(*topology.SelectedServer); ok {
+		desc = legacySs.Description()
+		conn, err = legacySs.ConnectionLegacy(ctx)
+	}
+	if err != nil {
+		return result.KillCursors{}, err
+	}
+	defer conn.Close()
+
+	if desc.WireVersion == nil || desc.WireVersion.Max < 4 {
+		return result.KillCursors{}, legacyKillCursors(ctx, ns, cursorID, conn)
+	}
+
+	cmd := command.KillCursors{
+		NS:  ns,
+		IDs: []int64{cursorID},
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}
+
+func legacyKillCursors(ctx context.Context, ns command.Namespace, cursorID int64, conn connection.Connection) error {
+	kc := wiremessage.KillCursors{
+		NumberOfCursorIDs: 1,
+		CursorIDs:         []int64{cursorID},
+		CollectionName:    ns.Collection,
+		DatabaseName:      ns.DB,
+	}
+
+	return conn.WriteWireMessage(ctx, kc)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/list_collections.go

@@ -0,0 +1,133 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"errors"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/connection"
+)
+
+// ErrFilterType is thrown when a non-string filter is specified.
+var ErrFilterType = errors.New("filter must be a string")
+
+// ListCollections handles the full cycle dispatch and execution of a listCollections command against the provided
+// topology.
+func ListCollections(
+	ctx context.Context,
+	cmd command.ListCollections,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.ListCollectionsOptions,
+) (*ListCollectionsBatchCursor, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	if ss.Description().WireVersion.Max < 3 {
+		return legacyListCollections(ctx, cmd, ss, conn)
+	}
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return nil, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	lc := options.MergeListCollectionsOptions(opts...)
+	if lc.NameOnly != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"nameOnly", bsonx.Boolean(*lc.NameOnly)})
+	}
+
+	res, err := cmd.RoundTrip(ctx, ss.Description(), conn)
+	if err != nil {
+		closeImplicitSession(cmd.Session)
+		return nil, err
+	}
+
+	batchCursor, err := NewBatchCursor(bsoncore.Document(res), cmd.Session, cmd.Clock, ss.Server, cmd.CursorOpts...)
+	if err != nil {
+		closeImplicitSession(cmd.Session)
+		return nil, err
+	}
+
+	return NewListCollectionsBatchCursor(batchCursor)
+}
+
+func legacyListCollections(
+	ctx context.Context,
+	cmd command.ListCollections,
+	ss *topology.SelectedServer,
+	conn connection.Connection,
+) (*ListCollectionsBatchCursor, error) {
+	filter, err := transformFilter(cmd.Filter, cmd.DB)
+	if err != nil {
+		return nil, err
+	}
+
+	findCmd := command.Find{
+		NS:       command.NewNamespace(cmd.DB, "system.namespaces"),
+		ReadPref: cmd.ReadPref,
+		Filter:   filter,
+	}
+
+	// don't need registry because it's used to create BSON docs for find options that don't exist in this case
+	batchCursor, err := legacyFind(ctx, findCmd, nil, ss, conn)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewLegacyListCollectionsBatchCursor(batchCursor)
+}
+
+// modify the user-supplied filter to prefix the "name" field with the database name.
+// returns the original filter if the name field is not present or a copy with the modified name field if it is
+func transformFilter(filter bsonx.Doc, dbName string) (bsonx.Doc, error) {
+	if filter == nil {
+		return filter, nil
+	}
+
+	if nameVal, err := filter.LookupErr("name"); err == nil {
+		name, ok := nameVal.StringValueOK()
+		if !ok {
+			return nil, ErrFilterType
+		}
+
+		filterCopy := filter.Copy()
+		filterCopy.Set("name", bsonx.String(dbName+"."+name))
+		return filterCopy, nil
+	}
+	return filter, nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/list_collections_batch_cursor.go

@@ -0,0 +1,124 @@
+package driverlegacy
+
+import (
+	"context"
+	"errors"
+	"io"
+	"strings"
+
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver"
+)
+
+// ListCollectionsBatchCursor is a special batch cursor returned from ListCollections that properly
+// handles current and legacy ListCollections operations.
+type ListCollectionsBatchCursor struct {
+	legacy       bool
+	bc           *BatchCursor
+	currentBatch *bsoncore.DocumentSequence
+	err          error
+}
+
+// NewListCollectionsBatchCursor creates a new non-legacy ListCollectionsCursor.
+func NewListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
+	if bc == nil {
+		return nil, errors.New("batch cursor must not be nil")
+	}
+	return &ListCollectionsBatchCursor{bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
+}
+
+// NewLegacyListCollectionsBatchCursor creates a new legacy ListCollectionsCursor.
+func NewLegacyListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
+	if bc == nil {
+		return nil, errors.New("batch cursor must not be nil")
+	}
+	return &ListCollectionsBatchCursor{legacy: true, bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
+}
+
+// ID returns the cursor ID for this batch cursor.
+func (lcbc *ListCollectionsBatchCursor) ID() int64 {
+	return lcbc.bc.ID()
+}
+
+// Next indicates if there is another batch available. Returning false does not necessarily indicate
+// that the cursor is closed. This method will return false when an empty batch is returned.
+//
+// If Next returns true, there is a valid batch of documents available. If Next returns false, there
+// is not a valid batch of documents available.
+func (lcbc *ListCollectionsBatchCursor) Next(ctx context.Context) bool {
+	if !lcbc.bc.Next(ctx) {
+		return false
+	}
+
+	if !lcbc.legacy {
+		lcbc.currentBatch.Style = lcbc.bc.currentBatch.Style
+		lcbc.currentBatch.Data = lcbc.bc.currentBatch.Data
+		lcbc.currentBatch.ResetIterator()
+		return true
+	}
+
+	lcbc.currentBatch.Style = bsoncore.SequenceStyle
+	lcbc.currentBatch.Data = lcbc.currentBatch.Data[:0]
+
+	var doc bsoncore.Document
+	for {
+		doc, lcbc.err = lcbc.bc.currentBatch.Next()
+		if lcbc.err != nil {
+			if lcbc.err == io.EOF {
+				lcbc.err = nil
+				break
+			}
+			return false
+		}
+		doc, lcbc.err = lcbc.projectNameElement(doc)
+		if lcbc.err != nil {
+			return false
+		}
+		lcbc.currentBatch.Data = append(lcbc.currentBatch.Data, doc...)
+	}
+
+	return true
+}
+
+// Batch will return a DocumentSequence for the current batch of documents. The returned
+// DocumentSequence is only valid until the next call to Next or Close.
+func (lcbc *ListCollectionsBatchCursor) Batch() *bsoncore.DocumentSequence { return lcbc.currentBatch }
+
+// Server returns a pointer to the cursor's server.
+func (lcbc *ListCollectionsBatchCursor) Server() driver.Server { return lcbc.bc.server }
+
+// Err returns the latest error encountered.
+func (lcbc *ListCollectionsBatchCursor) Err() error {
+	if lcbc.err != nil {
+		return lcbc.err
+	}
+	return lcbc.bc.Err()
+}
+
+// Close closes this batch cursor.
+func (lcbc *ListCollectionsBatchCursor) Close(ctx context.Context) error { return lcbc.bc.Close(ctx) }
+
+// project out the database name for a legacy server
+func (*ListCollectionsBatchCursor) projectNameElement(rawDoc bsoncore.Document) (bsoncore.Document, error) {
+	elems, err := rawDoc.Elements()
+	if err != nil {
+		return nil, err
+	}
+
+	var filteredElems []byte
+	for _, elem := range elems {
+		key := elem.Key()
+		if key != "name" {
+			filteredElems = append(filteredElems, elem...)
+			continue
+		}
+
+		name := elem.Value().StringValue()
+		collName := name[strings.Index(name, ".")+1:]
+		filteredElems = bsoncore.AppendStringElement(filteredElems, "name", collName)
+	}
+
+	var filteredDoc []byte
+	filteredDoc = bsoncore.BuildDocument(filteredDoc, filteredElems)
+	return filteredDoc, nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/list_databases.go

@@ -0,0 +1,60 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// ListDatabases handles the full cycle dispatch and execution of a listDatabases command against the provided
+// topology.
+func ListDatabases(
+	ctx context.Context,
+	cmd command.ListDatabases,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.ListDatabasesOptions,
+) (result.ListDatabases, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.ListDatabases{}, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return result.ListDatabases{}, err
+	}
+	defer conn.Close()
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.ListDatabases{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	ld := options.MergeListDatabasesOptions(opts...)
+	if ld.NameOnly != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"nameOnly", bsonx.Boolean(*ld.NameOnly)})
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/list_indexes.go

@@ -0,0 +1,105 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"time"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/connection"
+)
+
+// ListIndexes handles the full cycle dispatch and execution of a listIndexes command against the provided
+// topology.
+func ListIndexes(
+	ctx context.Context,
+	cmd command.ListIndexes,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	opts ...*options.ListIndexesOptions,
+) (*BatchCursor, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	if ss.Description().WireVersion.Max < 3 {
+		return legacyListIndexes(ctx, cmd, ss, conn, opts...)
+	}
+
+	lio := options.MergeListIndexesOptions(opts...)
+	if lio.BatchSize != nil {
+		elem := bsonx.Elem{"batchSize", bsonx.Int32(*lio.BatchSize)}
+		cmd.Opts = append(cmd.Opts, elem)
+		cmd.CursorOpts = append(cmd.CursorOpts, elem)
+	}
+	if lio.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"maxTimeMS", bsonx.Int64(int64(*lio.MaxTime / time.Millisecond))})
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	res, err := cmd.RoundTrip(ctx, ss.Description(), conn)
+	if err != nil {
+		closeImplicitSession(cmd.Session)
+		return nil, err
+	}
+
+	return NewBatchCursor(bsoncore.Document(res), cmd.Session, cmd.Clock, ss.Server, cmd.CursorOpts...)
+}
+
+func legacyListIndexes(
+	ctx context.Context,
+	cmd command.ListIndexes,
+	ss *topology.SelectedServer,
+	conn connection.Connection,
+	opts ...*options.ListIndexesOptions,
+) (*BatchCursor, error) {
+	lio := options.MergeListIndexesOptions(opts...)
+	ns := cmd.NS.DB + "." + cmd.NS.Collection
+
+	findCmd := command.Find{
+		NS: command.NewNamespace(cmd.NS.DB, "system.indexes"),
+		Filter: bsonx.Doc{
+			{"ns", bsonx.String(ns)},
+		},
+	}
+
+	findOpts := options.Find()
+	if lio.BatchSize != nil {
+		findOpts.SetBatchSize(*lio.BatchSize)
+	}
+	if lio.MaxTime != nil {
+		findOpts.SetMaxTime(*lio.MaxTime)
+	}
+
+	return legacyFind(ctx, findCmd, nil, ss, conn, findOpts)
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/models.go

@@ -0,0 +1,81 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+// WriteModel is the interface satisfied by all models for bulk writes.
+type WriteModel interface {
+	writeModel()
+}
+
+// InsertOneModel is the write model for insert operations.
+type InsertOneModel struct {
+	Document interface{}
+}
+
+func (InsertOneModel) writeModel() {}
+
+// DeleteOneModel is the write model for delete operations.
+type DeleteOneModel struct {
+	Filter    interface{}
+	Collation *options.Collation
+}
+
+func (DeleteOneModel) writeModel() {}
+
+// DeleteManyModel is the write model for deleteMany operations.
+type DeleteManyModel struct {
+	Filter    interface{}
+	Collation *options.Collation
+}
+
+func (DeleteManyModel) writeModel() {}
+
+// UpdateModel contains the fields that are shared between the ReplaceOneModel, UpdateOneModel, and UpdateManyModel types
+type UpdateModel struct {
+	Collation *options.Collation
+	Upsert    bool
+	UpsertSet bool
+}
+
+// ReplaceOneModel is the write model for replace operations.
+type ReplaceOneModel struct {
+	Filter      interface{}
+	Replacement interface{}
+	UpdateModel
+}
+
+func (ReplaceOneModel) writeModel() {}
+
+// UpdateOneModel is the write model for update operations.
+type UpdateOneModel struct {
+	Filter interface{}
+	Update interface{}
+	// default is to not send a value. for servers < 3.6, error raised if value given. for unack writes using opcodes,
+	// error raised if value given
+	ArrayFilters    options.ArrayFilters
+	ArrayFiltersSet bool
+	UpdateModel
+}
+
+func (UpdateOneModel) writeModel() {}
+
+// UpdateManyModel is the write model for updateMany operations.
+type UpdateManyModel struct {
+	Filter interface{}
+	Update interface{}
+	// default is to not send a value. for servers < 3.6, error raised if value given. for unack writes using opcodes,
+	// error raised if value given
+	ArrayFilters    options.ArrayFilters
+	ArrayFiltersSet bool
+	UpdateModel
+}
+
+func (UpdateManyModel) writeModel() {}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/read.go

@@ -0,0 +1,88 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo/readpref"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// Read handles the full cycle dispatch and execution of a read command against the provided
+// topology.
+func Read(
+	ctx context.Context,
+	cmd command.Read,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+) (bson.Raw, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	if cmd.Session != nil && cmd.Session.TransactionRunning() {
+		// When command.read is directly used, this implies an operation level
+		// read preference, so we do not override it with the transaction read pref.
+		err = checkTransactionReadPref(cmd.ReadPref)
+
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, ss.Description(), conn)
+}
+
+func getReadPrefBasedOnTransaction(current *readpref.ReadPref, sess *session.Client) (*readpref.ReadPref, error) {
+	if sess != nil && sess.TransactionRunning() {
+		// Transaction's read preference always takes priority
+		current = sess.CurrentRp
+		err := checkTransactionReadPref(current)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return current, nil
+}
+
+func checkTransactionReadPref(pref *readpref.ReadPref) error {
+	if pref != nil && (pref.Mode() == readpref.SecondaryMode ||
+		pref.Mode() == readpref.SecondaryPreferredMode ||
+		pref.Mode() == readpref.NearestMode ||
+		pref.Mode() == readpref.PrimaryPreferredMode) {
+		return command.ErrNonPrimaryRP
+	}
+	return nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/read_cursor.go

@@ -0,0 +1,72 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/x/bsonx"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// ReadCursor handles the full dispatch cycle and execution of a read command against the provided topology and returns
+// a Cursor over the resulting BSON reader.
+func ReadCursor(
+	ctx context.Context,
+	cmd command.Read,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	cursorOpts ...bsonx.Elem,
+) (*BatchCursor, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	rdr, err := cmd.RoundTrip(ctx, desc, conn)
+	if err != nil {
+		if cmd.Session != nil && cmd.Session.SessionType == session.Implicit {
+			cmd.Session.EndSession()
+		}
+		return nil, err
+	}
+
+	cursor, err := NewBatchCursor(bsoncore.Document(rdr), cmd.Session, cmd.Clock, ss.Server, cursorOpts...)
+	if err != nil {
+		if cmd.Session != nil && cmd.Session.SessionType == session.Implicit {
+			cmd.Session.EndSession()
+		}
+		return nil, err
+	}
+
+	return cursor, nil
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/update.go

@@ -0,0 +1,151 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+	"go.mongodb.org/mongo-driver/x/network/result"
+)
+
+// Update handles the full cycle dispatch and execution of an update command against the provided
+// topology.
+func Update(
+	ctx context.Context,
+	cmd command.Update,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	retryWrite bool,
+	opts ...*options.UpdateOptions,
+) (result.Update, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return result.Update{}, err
+	}
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return result.Update{}, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	updateOpts := options.MergeUpdateOptions(opts...)
+
+	if updateOpts.ArrayFilters != nil {
+		if ss.Description().WireVersion.Max < 6 {
+			return result.Update{}, ErrArrayFilters
+		}
+		filters, err := updateOpts.ArrayFilters.ToArray()
+		if err != nil {
+			return result.Update{}, err
+		}
+		arr := make(bsonx.Arr, 0, len(filters))
+		for _, filter := range filters {
+			doc, err := bsonx.ReadDoc(filter)
+			if err != nil {
+				return result.Update{}, err
+			}
+			arr = append(arr, bsonx.Document(doc))
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"arrayFilters", bsonx.Array(arr)})
+	}
+	if updateOpts.BypassDocumentValidation != nil && ss.Description().WireVersion.Includes(4) {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"bypassDocumentValidation", bsonx.Boolean(*updateOpts.BypassDocumentValidation)})
+	}
+	if updateOpts.Collation != nil {
+		if ss.Description().WireVersion.Max < 5 {
+			return result.Update{}, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(updateOpts.Collation.ToDocument())
+		if err != nil {
+			return result.Update{}, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if updateOpts.Upsert != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"upsert", bsonx.Boolean(*updateOpts.Upsert)})
+	}
+
+	// Execute in a single trip if retry writes not supported, or retry not enabled
+	if !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) || !retryWrite {
+		if cmd.Session != nil {
+			cmd.Session.RetryWrite = false // explicitly set to false to prevent encoding transaction number
+		}
+		return update(ctx, &cmd, ss, nil)
+	}
+
+	cmd.Session.RetryWrite = retryWrite
+	cmd.Session.IncrementTxnNumber()
+
+	res, originalErr := update(ctx, &cmd, ss, nil)
+
+	// Retry if appropriate
+	if cerr, ok := originalErr.(command.Error); (ok && cerr.Retryable()) ||
+		(res.WriteConcernError != nil && command.IsWriteConcernErrorRetryable(res.WriteConcernError)) {
+		ss, err := topo.SelectServerLegacy(ctx, selector)
+
+		// Return original error if server selection fails or new server does not support retryable writes
+		if err != nil || !retrySupported(topo, ss.Description(), cmd.Session, cmd.WriteConcern) {
+			return res, originalErr
+		}
+
+		return update(ctx, &cmd, ss, cerr)
+	}
+	return res, originalErr
+
+}
+
+func update(
+	ctx context.Context,
+	cmd *command.Update,
+	ss *topology.SelectedServer,
+	oldErr error,
+) (result.Update, error) {
+	desc := ss.Description()
+
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		if oldErr != nil {
+			return result.Update{}, oldErr
+		}
+		return result.Update{}, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return result.Update{}, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	res, err := cmd.RoundTrip(ctx, desc, conn)
+	ss.ProcessWriteConcernError(res.WriteConcernError)
+	return res, err
+}

vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/write.go

@@ -0,0 +1,82 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package driverlegacy
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo/writeconcern"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// Write handles the full cycle dispatch and execution of a write command against the provided
+// topology.
+func Write(
+	ctx context.Context,
+	cmd command.Write,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+) (bson.Raw, error) {
+
+	if cmd.Session != nil && cmd.Session.PinnedServer != nil {
+		selector = cmd.Session.PinnedServer
+	}
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return nil, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if !writeconcern.AckWrite(cmd.WriteConcern) {
+		go func() {
+			defer func() { _ = recover() }()
+			defer conn.Close()
+
+			_, _ = cmd.RoundTrip(ctx, desc, conn)
+		}()
+
+		return nil, command.ErrUnacknowledgedWrite
+	}
+	defer conn.Close()
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return nil, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}
+
+// Retryable writes are supported if the server supports sessions, the operation is not
+// within a transaction, and the write is acknowledged
+func retrySupported(
+	topo *topology.Topology,
+	desc description.SelectedServer,
+	sess *session.Client,
+	wc *writeconcern.WriteConcern,
+) bool {
+	return topo.SupportsSessions() &&
+		description.SessionsSupported(desc.WireVersion) &&
+		!(sess.TransactionInProgress() || sess.TransactionStarting()) &&
+		writeconcern.AckWrite(wc)
+}