Primary key refactoring re. Un/Marshaling of JSON and the unique keys, plus the ApplyDelta() and 'defensive' changes introduced by Kortshack, also did some tidying up.

graph/primarykey.go

@@ -15,46 +15,64 @@
 package graph
 
 import (
+	"code.google.com/p/go-uuid/uuid"
 	"encoding/json"
+	"errors"
+	"github.com/barakmich/glog"
 	"strconv"
 	"sync"
 )
 
-// Defines the PrimaryKey interface, this abstracts the generation of IDs
-
 type primaryKeyType uint8
 
 const (
 	none primaryKeyType = iota
 	sequential
+	unique
 )
 
 type PrimaryKey struct {
-	keyType      primaryKeyType
+	KeyType      primaryKeyType
 	mut          sync.Mutex
-	sequentialID int64
+	SequentialID int64
+	UniqueID     string
 }
 
 func NewSequentialKey(horizon int64) PrimaryKey {
 	return PrimaryKey{
-		keyType:      sequential,
-		sequentialID: horizon,
+		KeyType:      sequential,
+		SequentialID: horizon,
+	}
+}
+
+func NewUniqueKey(horizon string) PrimaryKey {
+	id := uuid.Parse(horizon)
+	if id == nil {
+		id = uuid.NewUUID()
+	}
+	return PrimaryKey{
+		KeyType:  unique,
+		UniqueID: id.String(),
 	}
 }
 
 func (p *PrimaryKey) Next() PrimaryKey {
-	switch p.keyType {
+	switch p.KeyType {
 	case sequential:
 		p.mut.Lock()
 		defer p.mut.Unlock()
-		p.sequentialID++
-		if p.sequentialID <= 0 {
-			p.sequentialID = 1
+		p.SequentialID++
+		if p.SequentialID <= 0 {
+			p.SequentialID = 1
 		}
 		return PrimaryKey{
-			keyType:      sequential,
-			sequentialID: p.sequentialID,
+			KeyType:      sequential,
+			SequentialID: p.SequentialID,
 		}
+	case unique:
+		id := uuid.NewUUID()
+		p.UniqueID = id.String()
+		return *p
 	case none:
 		panic("Calling next() on a none PrimaryKey")
 	}
@@ -62,27 +80,50 @@ func (p *PrimaryKey) Next() PrimaryKey {
 }
 
 func (p *PrimaryKey) Int() int64 {
-	switch p.keyType {
+	switch p.KeyType {
 	case sequential:
-		return p.sequentialID
+		return p.SequentialID
+	case unique:
+		glog.Fatal("UUID cannot be cast to an int64")
+		return -1
 	}
 	return -1
 }
 
 func (p *PrimaryKey) String() string {
-	// More options for more keyTypes
-	return strconv.FormatInt(p.sequentialID, 10)
+	switch p.KeyType {
+	case sequential:
+		return strconv.FormatInt(p.SequentialID, 10)
+	case unique:
+		return p.UniqueID
+	case none:
+		panic("Calling String() on a none PrimaryKey")
+	}
+	return ""
 }
 
 func (p *PrimaryKey) MarshalJSON() ([]byte, error) {
-	return json.Marshal(p.sequentialID)
+	if p.KeyType == none {
+		return nil, errors.New("Cannot marshal PrimaryKey with KeyType of 'none'")
+	}
+	return json.Marshal(*p)
 }
 
+//To avoid recursion in the implmentation of the UnmarshalJSON interface below
+type primaryKey PrimaryKey
+
 func (p *PrimaryKey) UnmarshalJSON(bytes []byte) error {
 	/* Careful special casing here. For example, string-related things might begin
 	if bytes[0] == '"' {
 	}
 	*/
-	p.keyType = sequential
-	return json.Unmarshal(bytes, &p.sequentialID)
+	temp := primaryKey{}
+	if err := json.Unmarshal(bytes, &temp); err != nil {
+		return err
+	}
+	*p = (PrimaryKey)(temp)
+	if p.KeyType == none {
+		return errors.New("Could not properly unmarshal primary key, 'none' keytype detected")
+	}
+	return nil
 }