forked from golang/hotime
89 lines
2.1 KiB
Go
89 lines
2.1 KiB
Go
|
// 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)
|
||
|
|
}
|
||
|
|
|
||
|
|
// String returns the string representation of mode.
|
||
|
|
func (mode Mode) String() string {
|
||
|
|
switch mode {
|
||
|
|
case PrimaryMode:
|
||
|
|
return "primary"
|
||
|
|
case PrimaryPreferredMode:
|
||
|
|
return "primaryPreferred"
|
||
|
|
case SecondaryMode:
|
||
|
|
return "secondary"
|
||
|
|
case SecondaryPreferredMode:
|
||
|
|
return "secondaryPreferred"
|
||
|
|
case NearestMode:
|
||
|
|
return "nearest"
|
||
|
|
default:
|
||
|
|
return "unknown"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// IsValid checks whether the mode is valid.
|
||
|
|
func (mode Mode) IsValid() bool {
|
||
|
|
switch mode {
|
||
|
|
case PrimaryMode,
|
||
|
|
PrimaryPreferredMode,
|
||
|
|
SecondaryMode,
|
||
|
|
SecondaryPreferredMode,
|
||
|
|
NearestMode:
|
||
|
|
return true
|
||
|
|
default:
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
}
|