Eager workflow dispatch

common/metrics/metric_defs.go

@@ -1463,6 +1463,7 @@ var (
 	CommandTypeModifyWorkflowPropertiesCounter        = NewCounterDef("modify_workflow_properties_command")
 	CommandTypeChildWorkflowCounter                   = NewCounterDef("child_workflow_command")
 	ActivityEagerExecutionCounter                     = NewCounterDef("activity_eager_execution")
+	WorkflowEagerExecutionCounter                     = NewCounterDef("workflow_eager_execution")
 	EmptyCompletionCommandsCounter                    = NewCounterDef("empty_completion_commands")
 	MultipleCompletionCommandsCounter                 = NewCounterDef("multiple_completion_commands")
 	FailedWorkflowTasksCounter                        = NewCounterDef("failed_workflow_tasks")

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

@@ -406,7 +406,7 @@ 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
@@ -2864,6 +2864,7 @@ 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 +99,31 @@ 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 requestEagerExecution {
+		_, _, 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 +161,13 @@ 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 +283,6 @@ 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,