66 lines
2.0 KiB
Go
66 lines
2.0 KiB
Go
package uuid
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import (
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"fmt"
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)
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// Sequence represents an iterated value to help ensure unique UUID generations
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// values across the same domain, server restarts and clock issues.
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type Sequence uint16
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// Node represents the last node id setup used by the generator.
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type Node []byte
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// Store is used for storage of UUID generation history to ensure continuous
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// running of the UUID generator between restarts and to monitor synchronicity
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// while generating new V1 or V2 UUIDs.
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type Store struct {
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Timestamp
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Sequence
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Node
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}
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// String returns a string representation of the Store.
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func (o Store) String() string {
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return fmt.Sprintf("Timestamp[%s]-Sequence[%d]-Node[%x]", o.Timestamp, o.Sequence, o.Node)
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}
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// Saver is an interface to setup a non volatile store within your system
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// if you wish to use V1 and V2 UUIDs based on your node id and a constant time
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// it is highly recommended to implement this.
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// A default implementation has been provided. FileSystemStorage, the default
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// behaviour of the package is to generate random sequences where a Saver is not
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// specified.
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type Saver interface {
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// Read is run once, use this to setup your UUID state machine
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// Read should also return the UUID state from the non volatile store
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Read() (Store, error)
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// Save saves the state to the non volatile store and is called only if
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Save(Store)
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// Init allows default setup of a new Saver
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Init() Saver
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}
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// RegisterSaver register's a uuid.Saver implementation to the default package
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// uuid.Generator. If you wish to save the generator state, this function must
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// be run before any calls to V1 or V2 UUIDs. uuid.RegisterSaver cannot be run
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// in conjunction with uuid.Init. You may implement the uuid.Saver interface
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// or use the provided uuid.Saver's from the uuid/savers package.
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func RegisterSaver(saver Saver) (err error) {
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notOnce := true
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once.Do(func() {
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generator.Lock()
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generator.Saver = saver
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generator.Unlock()
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err = generator.init()
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notOnce = false
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return
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})
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if notOnce {
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panic("uuid: Register* methods cannot be called more than once.")
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}
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return
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}
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