init commit

vendor/github.com/twinj/uuid/saver.go

@@ -0,0 +1,65 @@
+package uuid
+
+import (
+	"fmt"
+)
+
+// Sequence represents an iterated value to help ensure unique UUID generations
+// values across the same domain, server restarts and clock issues.
+type Sequence uint16
+
+// Node represents the last node id setup used by the generator.
+type Node []byte
+
+// Store is used for storage of UUID generation history to ensure continuous
+// running of the UUID generator between restarts and to monitor synchronicity
+// while generating new V1 or V2 UUIDs.
+type Store struct {
+	Timestamp
+	Sequence
+	Node
+}
+
+// String returns a string representation of the Store.
+func (o Store) String() string {
+	return fmt.Sprintf("Timestamp[%s]-Sequence[%d]-Node[%x]", o.Timestamp, o.Sequence, o.Node)
+}
+
+// Saver is an interface to setup a non volatile store within your system
+// if you wish to use V1 and V2 UUIDs based on your node id and a constant time
+// it is highly recommended to implement this.
+// A default implementation has been provided. FileSystemStorage, the default
+// behaviour of the package is to generate random sequences where a Saver is not
+// specified.
+type Saver interface {
+	// Read is run once, use this to setup your UUID state machine
+	// Read should also return the UUID state from the non volatile store
+	Read() (Store, error)
+
+	// Save saves the state to the non volatile store and is called only if
+	Save(Store)
+
+	// Init allows default setup of a new Saver
+	Init() Saver
+}
+
+// RegisterSaver register's a uuid.Saver implementation to the default package
+// uuid.Generator. If you wish to save the generator state, this function must
+// be run before any calls to V1 or V2 UUIDs. uuid.RegisterSaver cannot be run
+// in conjunction with uuid.Init. You may implement the uuid.Saver interface
+// or use the provided uuid.Saver's from the uuid/savers package.
+func RegisterSaver(saver Saver) (err error) {
+	notOnce := true
+	once.Do(func() {
+		generator.Lock()
+		generator.Saver = saver
+		generator.Unlock()
+		err = generator.init()
+		notOnce = false
+		return
+	})
+	if notOnce {
+		panic("uuid: Register* methods cannot be called more than once.")
+	}
+	return
+}