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vendor/go.mongodb.org/mongo-driver/mongo/readpref/mode.go

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+// 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 readpref
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Mode indicates the user's preference on reads.
+type Mode uint8
+
+// Mode constants
+const (
+	_ Mode = iota
+	// PrimaryMode indicates that only a primary is
+	// considered for reading. This is the default
+	// mode.
+	PrimaryMode
+	// PrimaryPreferredMode indicates that if a primary
+	// is available, use it; otherwise, eligible
+	// secondaries will be considered.
+	PrimaryPreferredMode
+	// SecondaryMode indicates that only secondaries
+	// should be considered.
+	SecondaryMode
+	// SecondaryPreferredMode indicates that only secondaries
+	// should be considered when one is available. If none
+	// are available, then a primary will be considered.
+	SecondaryPreferredMode
+	// NearestMode indicates that all primaries and secondaries
+	// will be considered.
+	NearestMode
+)
+
+// ModeFromString returns a mode corresponding to
+// mode.
+func ModeFromString(mode string) (Mode, error) {
+	switch strings.ToLower(mode) {
+	case "primary":
+		return PrimaryMode, nil
+	case "primarypreferred":
+		return PrimaryPreferredMode, nil
+	case "secondary":
+		return SecondaryMode, nil
+	case "secondarypreferred":
+		return SecondaryPreferredMode, nil
+	case "nearest":
+		return NearestMode, nil
+	}
+	return Mode(0), fmt.Errorf("unknown read preference %v", mode)
+}

vendor/go.mongodb.org/mongo-driver/mongo/readpref/options.go

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+// 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 readpref
+
+import (
+	"errors"
+	"time"
+
+	"go.mongodb.org/mongo-driver/tag"
+)
+
+// ErrInvalidTagSet indicates that an invalid set of tags was specified.
+var ErrInvalidTagSet = errors.New("an even number of tags must be specified")
+
+// Option configures a read preference
+type Option func(*ReadPref) error
+
+// WithMaxStaleness sets the maximum staleness a
+// server is allowed.
+func WithMaxStaleness(ms time.Duration) Option {
+	return func(rp *ReadPref) error {
+		rp.maxStaleness = ms
+		rp.maxStalenessSet = true
+		return nil
+	}
+}
+
+// WithTags sets a single tag set used to match
+// a server. The last call to WithTags or WithTagSets
+// overrides all previous calls to either method.
+func WithTags(tags ...string) Option {
+	return func(rp *ReadPref) error {
+		length := len(tags)
+		if length < 2 || length%2 != 0 {
+			return ErrInvalidTagSet
+		}
+
+		tagset := make(tag.Set, 0, length/2)
+
+		for i := 1; i < length; i += 2 {
+			tagset = append(tagset, tag.Tag{Name: tags[i-1], Value: tags[i]})
+		}
+
+		return WithTagSets(tagset)(rp)
+	}
+}
+
+// WithTagSets sets the tag sets used to match
+// a server. The last call to WithTags or WithTagSets
+// overrides all previous calls to either method.
+func WithTagSets(tagSets ...tag.Set) Option {
+	return func(rp *ReadPref) error {
+		rp.tagSets = tagSets
+		return nil
+	}
+}

vendor/go.mongodb.org/mongo-driver/mongo/readpref/readpref.go

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+// 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 readpref // import "go.mongodb.org/mongo-driver/mongo/readpref"
+
+import (
+	"errors"
+	"time"
+
+	"go.mongodb.org/mongo-driver/tag"
+)
+
+var (
+	errInvalidReadPreference = errors.New("can not specify tags or max staleness on primary")
+)
+
+var primary = ReadPref{mode: PrimaryMode}
+
+// Primary constructs a read preference with a PrimaryMode.
+func Primary() *ReadPref {
+	return &primary
+}
+
+// PrimaryPreferred constructs a read preference with a PrimaryPreferredMode.
+func PrimaryPreferred(opts ...Option) *ReadPref {
+	// New only returns an error with a mode of Primary
+	rp, _ := New(PrimaryPreferredMode, opts...)
+	return rp
+}
+
+// SecondaryPreferred constructs a read preference with a SecondaryPreferredMode.
+func SecondaryPreferred(opts ...Option) *ReadPref {
+	// New only returns an error with a mode of Primary
+	rp, _ := New(SecondaryPreferredMode, opts...)
+	return rp
+}
+
+// Secondary constructs a read preference with a SecondaryMode.
+func Secondary(opts ...Option) *ReadPref {
+	// New only returns an error with a mode of Primary
+	rp, _ := New(SecondaryMode, opts...)
+	return rp
+}
+
+// Nearest constructs a read preference with a NearestMode.
+func Nearest(opts ...Option) *ReadPref {
+	// New only returns an error with a mode of Primary
+	rp, _ := New(NearestMode, opts...)
+	return rp
+}
+
+// New creates a new ReadPref.
+func New(mode Mode, opts ...Option) (*ReadPref, error) {
+	rp := &ReadPref{
+		mode: mode,
+	}
+
+	if mode == PrimaryMode && len(opts) != 0 {
+		return nil, errInvalidReadPreference
+	}
+
+	for _, opt := range opts {
+		err := opt(rp)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return rp, nil
+}
+
+// ReadPref determines which servers are considered suitable for read operations.
+type ReadPref struct {
+	maxStaleness    time.Duration
+	maxStalenessSet bool
+	mode            Mode
+	tagSets         []tag.Set
+}
+
+// MaxStaleness is the maximum amount of time to allow
+// a server to be considered eligible for selection. The
+// second return value indicates if this value has been set.
+func (r *ReadPref) MaxStaleness() (time.Duration, bool) {
+	return r.maxStaleness, r.maxStalenessSet
+}
+
+// Mode indicates the mode of the read preference.
+func (r *ReadPref) Mode() Mode {
+	return r.mode
+}
+
+// TagSets are multiple tag sets indicating
+// which servers should be considered.
+func (r *ReadPref) TagSets() []tag.Set {
+	return r.tagSets
+}