Eager workflow dispatch

common/dynamicconfig/constants.go

@@ -87,8 +87,11 @@ const (
 	EnableParentClosePolicyWorker = "system.enableParentClosePolicyWorker"
 	// EnableStickyQuery indicates if sticky query should be enabled per namespace
 	EnableStickyQuery = "system.enableStickyQuery"
-	// EnableActivityEagerExecution indicates if acitivty eager execution is enabled per namespace
+	// EnableActivityEagerExecution indicates if activity eager execution is enabled per namespace
 	EnableActivityEagerExecution = "system.enableActivityEagerExecution"
+	// EnableEagerWorkflowStart toggles "eager workflow start" - returning the first workflow task inline in the
+	// response to a StartWorkflowExecution request and skipping the trip through matching.
+	EnableEagerWorkflowStart = "system.enableEagerWorkflowStart"
 	// NamespaceCacheRefreshInterval is the key for namespace cache refresh interval dynamic config
 	NamespaceCacheRefreshInterval = "system.namespaceCacheRefreshInterval"
 

common/metrics/metric_defs.go

@@ -1464,7 +1464,14 @@ var (
 	MessageTypeCompleteWorkflowExecutionUpdateCounter = NewCounterDef("complete_workflow_update_message")
 	MessageTypeRejectWorkflowExecutionUpdateCounter   = NewCounterDef("reject_workflow_update_message")
 
-	ActivityEagerExecutionCounter                  = NewCounterDef("activity_eager_execution")
+	ActivityEagerExecutionCounter = NewCounterDef("activity_eager_execution")
+	// WorkflowEagerExecutionCounter is emitted any time eager workflow start is requested.
+	WorkflowEagerExecutionCounter = NewCounterDef("workflow_eager_execution")
+	// WorkflowEagerExecutionDeniedCounter is emitted any time eager workflow start is requested and the serer fell back
+	// to standard dispatch.
+	// Timeouts and failures are not counted in this metric.
+	// This metric has a "reason" tag attached to it to understand why eager start was denied.
+	WorkflowEagerExecutionDeniedCounter            = NewCounterDef("workflow_eager_execution_denied")
 	EmptyCompletionCommandsCounter                 = NewCounterDef("empty_completion_commands")
 	MultipleCompletionCommandsCounter              = NewCounterDef("multiple_completion_commands")
 	FailedWorkflowTasksCounter                     = NewCounterDef("failed_workflow_tasks")

common/metrics/tags.go

@@ -51,6 +51,8 @@ const (
 	commandType    = "commandType"
 	serviceName    = "service_name"
 	actionType     = "action_type"
+	// Generic reason tag can be used anywhere a reason is needed.
+	reason = "reason"
 
 	namespaceAllValue = "all"
 	unknownValue      = "_unknown_"
@@ -278,3 +280,13 @@ func StringTag(key string, value string) Tag {
 func CacheTypeTag(value string) Tag {
 	return &tagImpl{key: CacheTypeTagName, value: value}
 }
+
+// ReasonString is just a string but the special type is defined here to remind callers of ReasonTag to limit the
+// cardinality of possible reasons.
+type ReasonString string
+
+// ReasonTag is a generic tag can be used anywhere a reason is needed.
+// Make sure that the value is of limited cardinality.
+func ReasonTag(value ReasonString) Tag {
+	return &tagImpl{key: reason, value: string(value)}
+}

config/dynamicconfig/development-cass.yaml

@@ -36,3 +36,5 @@
 #    constraints: {}
 #system.enableParentClosePolicyWorker:
 #  - value: true
+system.enableEagerWorkflowStart:
+  - value: true

config/dynamicconfig/development-sql.yaml

@@ -36,6 +36,8 @@
 #    constraints: {}
 #system.enableParentClosePolicyWorker:
 #  - value: true
+system.enableEagerWorkflowStart:
+  - value: true
 limit.maxIDLength:
   - value: 255
     constraints: {}

proto/internal/temporal/server/api/historyservice/v1/request_response.proto

@@ -66,6 +66,8 @@ message StartWorkflowExecutionRequest {
 message StartWorkflowExecutionResponse {
     string run_id = 1;
     temporal.server.api.clock.v1.VectorClock clock = 2;
+    // Set if request_eager_execution is set on the start request 
+    temporal.api.workflowservice.v1.PollWorkflowTaskQueueResponse eager_workflow_task = 3;
 }
 
 message GetMutableStateRequest {

service/frontend/workflow_handler.go

@@ -407,7 +407,7 @@ func (wh *WorkflowHandler) StartWorkflowExecution(ctx context.Context, request *
 	if err != nil {
 		return nil, err
 	}
-	return &workflowservice.StartWorkflowExecutionResponse{RunId: resp.GetRunId()}, nil
+	return &workflowservice.StartWorkflowExecutionResponse{RunId: resp.GetRunId(), EagerWorkflowTask: resp.GetEagerWorkflowTask()}, nil
 }
 
 // GetWorkflowExecutionHistory returns the history of specified workflow execution.  It fails with 'EntityNotExistError' if specified workflow
@@ -2866,6 +2866,7 @@ func (wh *WorkflowHandler) GetSystemInfo(ctx context.Context, request *workflows
 			SupportsSchedules:               true,
 			EncodedFailureAttributes:        true,
 			UpsertMemo:                      true,
+			EagerWorkflowStart:              true,
 		},
 	}, nil
 }

service/history/api/create_workflow_util.go

@@ -99,16 +99,32 @@ func NewWorkflowWithSignal(
 			return nil, err
 		}
 	}
-
+	requestEagerExecution := startRequest.StartRequest.GetRequestEagerExecution()
 	// Generate first workflow task event if not child WF and no first workflow task backoff
-	if err := GenerateFirstWorkflowTask(
+	scheduledEventID, err := GenerateFirstWorkflowTask(
 		newMutableState,
 		startRequest.ParentExecutionInfo,
 		startEvent,
-	); err != nil {
+		requestEagerExecution,
+	)
+	if err != nil {
 		return nil, err
 	}
 
+	// If first workflow task should back off (e.g. cron or workflow retry) a workflow task will not be scheduled.
+	if requestEagerExecution && newMutableState.HasPendingWorkflowTask() {
+		_, _, err = newMutableState.AddWorkflowTaskStartedEvent(
+			scheduledEventID,
+			startRequest.StartRequest.RequestId,
+			startRequest.StartRequest.TaskQueue,
+			startRequest.StartRequest.Identity,
+		)
+		if err != nil {
+			// Unable to add WorkflowTaskStarted event to history
+			return nil, err
+		}
+	}
+
 	newWorkflowContext := workflow.NewContext(
 		shard,
 		definition.NewWorkflowKey(
@@ -146,17 +162,13 @@ func GenerateFirstWorkflowTask(
 	mutableState workflow.MutableState,
 	parentInfo *workflowspb.ParentExecutionInfo,
 	startEvent *historypb.HistoryEvent,
-) error {
-
+	bypassTaskGeneration bool,
+) (int64, error) {
 	if parentInfo == nil {
 		// WorkflowTask is only created when it is not a Child Workflow and no backoff is needed
-		if err := mutableState.AddFirstWorkflowTaskScheduled(
-			startEvent,
-		); err != nil {
-			return err
-		}
+		return mutableState.AddFirstWorkflowTaskScheduled(startEvent, bypassTaskGeneration)
 	}
-	return nil
+	return 0, nil
 }
 
 func NewWorkflowVersionCheck(
@@ -272,7 +284,6 @@ func ValidateStartWorkflowExecutionRequest(
 	if err := common.ValidateRetryPolicy(request.RetryPolicy); err != nil {
 		return err
 	}
-
 	if err := ValidateStart(
 		ctx,
 		shard,

service/history/api/signalwithstartworkflow/signal_with_start_workflow.go

@@ -86,6 +86,7 @@ func startAndSignalWorkflow(
 ) (string, error) {
 	workflowID := signalWithStartRequest.GetWorkflowId()
 	runID := uuid.New().String()
+	// TODO(bergundy): Support eager workflow task
 	newWorkflowContext, err := api.NewWorkflowWithSignal(
 		ctx,
 		shard,