Remove lock on current workflow ID (#2872)

* Remove lock on current workflow ID since this lock is close to noop
  NOTE: all writes to DB are serialized by the shard lock

service/history/historyEngine.go

@@ -387,17 +387,6 @@ func (e *historyEngineImpl) StartWorkflowExecution(
 
 	workflowID := request.GetWorkflowId()
 	runID := uuid.New()
-	// grab the current context as a Lock, nothing more
-	_, currentRelease, err := e.historyCache.GetOrCreateCurrentWorkflowExecution(
-		ctx,
-		namespaceID,
-		workflowID,
-	)
-	if err != nil {
-		return nil, err
-	}
-	defer func() { currentRelease(retError) }()
-
 	workflowContext, err := api.NewWorkflowWithSignal(
 		e.shard,
 		namespaceEntry,

service/history/workflow/cache.go

@@ -53,12 +53,6 @@ type (
 	ReleaseCacheFunc func(err error)
 
 	Cache interface {
-		GetOrCreateCurrentWorkflowExecution(
-			ctx context.Context,
-			namespaceID namespace.ID,
-			workflowID string,
-		) (Context, ReleaseCacheFunc, error)
-
 		GetOrCreateWorkflowExecution(
 			ctx context.Context,
 			namespaceID namespace.ID,
@@ -101,34 +95,6 @@ func NewCache(shard shard.Context) Cache {
 	}
 }
 
-func (c *CacheImpl) GetOrCreateCurrentWorkflowExecution(
-	ctx context.Context,
-	namespaceID namespace.ID,
-	workflowID string,
-) (Context, ReleaseCacheFunc, error) {
-
-	scope := metrics.HistoryCacheGetOrCreateCurrentScope
-	c.metricsClient.IncCounter(scope, metrics.CacheRequests)
-	sw := c.metricsClient.StartTimer(scope, metrics.CacheLatency)
-	defer sw.Stop()
-
-	// using empty run ID as current workflow run ID
-	runID := ""
-	execution := commonpb.WorkflowExecution{
-		WorkflowId: workflowID,
-		RunId:      runID,
-	}
-
-	return c.getOrCreateWorkflowExecutionInternal(
-		ctx,
-		namespaceID,
-		execution,
-		scope,
-		true,
-		CallerTypeAPI,
-	)
-}
-
 func (c *CacheImpl) GetOrCreateWorkflowExecution(
 	ctx context.Context,
 	namespaceID namespace.ID,