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