Remove lock from ActorID

pkg/document/time/actor_id.go

@@ -23,7 +23,6 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"sync"
 )
 
 const actorIDSize = 12
@@ -57,13 +56,13 @@ var (
 	ErrInvalidActorID = errors.New("invalid actor id")
 )
 
-// ActorID is bytes represented by the hexadecimal string.
-// It should be generated by unique value.
+// ActorID represents the unique ID of the client. It is composed of 12 bytes.
+// It caches the string representation of ActorID to reduce the number of calls
+// to hex.EncodeToString. This causes a multi-routine problem, so it is
+// recommended to use it in a single routine or to use it after locking.
 type ActorID struct {
-	bytes [actorIDSize]byte
-
-	cachedString   string
-	cachedStringMu sync.RWMutex
+	bytes        [actorIDSize]byte
+	cachedString string
 }
 
 // ActorIDFromHex returns the bytes represented by the hexadecimal string str.
@@ -106,23 +105,6 @@ func ActorIDFromBytes(bytes []byte) (*ActorID, error) {
 // String returns the hexadecimal encoding of ActorID.
 // If the receiver is nil, it would return empty string.
 func (id *ActorID) String() string {
-	id.cachedStringMu.RLock()
-	readLocked := true
-	defer func() {
-		if readLocked {
-			id.cachedStringMu.RUnlock()
-		}
-	}()
-
-	if id.cachedString != "" {
-		return id.cachedString
-	}
-
-	id.cachedStringMu.RUnlock()
-	readLocked = false
-	id.cachedStringMu.Lock()
-	defer id.cachedStringMu.Unlock()
-
 	if id.cachedString == "" {
 		id.cachedString = hex.EncodeToString(id.bytes[:])
 	}

server/backend/sync/coordinator.go

@@ -54,9 +54,6 @@ type Coordinator interface {
 	// Publish publishes the given event.
 	Publish(ctx context.Context, publisherID *time.ActorID, event DocEvent)
 
-	// PublishToLocal publishes the given event.
-	PublishToLocal(ctx context.Context, publisherID *time.ActorID, event DocEvent)
-
 	// Members returns the members of this cluster.
 	Members() map[string]*ServerInfo
 

server/backend/sync/memory/coordinator.go

@@ -85,15 +85,9 @@ func (c *Coordinator) Publish(
 	publisherID *time.ActorID,
 	event sync.DocEvent,
 ) {
-	c.pubSub.Publish(ctx, publisherID, event)
-}
-
-// PublishToLocal publishes the given event.
-func (c *Coordinator) PublishToLocal(
-	ctx context.Context,
-	publisherID *time.ActorID,
-	event sync.DocEvent,
-) {
+	// NOTE(hackerwins): String() triggers the cache of ActorID to avoid
+	// race condition of concurrent access to the cache.
+	_ = event.Publisher.String()
 	c.pubSub.Publish(ctx, publisherID, event)
 }