runID being optional is moved from empty string to not specified. (#169)

Author: sivakku

client.go

@@ -46,7 +46,7 @@ type (
 
 		// SignalWorkflow sends a signals to a workflow in execution
 		// - workflow ID of the workflow.
-		// - runID can be optional if not specified it will pick the latest execution of that workflow ID.
+		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
 		// - signalName name to identify the signal.
 		// The errors it can return:
 		//	- EntityNotExistsError
@@ -55,7 +55,7 @@ type (
 
 		// CancelWorkflow cancels a workflow in execution
 		// - workflow ID of the workflow.
-		// - runID can be optional if not specified it will pick the latest execution of that workflow ID.
+		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
 		// The errors it can return:
 		//	- EntityNotExistsError
 		//	- BadRequestError
@@ -64,14 +64,17 @@ type (
 
 		// TerminateWorkflow terminates a workflow execution.
 		// workflowID is required, other parameters are optional.
-		// If runID is omit, it will terminate currently running workflow (if there is one) based on the workflowID.
+		// - workflow ID of the workflow.
+		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
 		// The errors it can return:
 		//	- EntityNotExistsError
 		//	- BadRequestError
 		//	- InternalServiceError
 		TerminateWorkflow(workflowID string, runID string, reason string, details []byte) error
 
 		// GetWorkflowHistory gets history of a particular workflow.
+		// - workflow ID of the workflow.
+		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
 		// The errors it can return:
 		//	- EntityNotExistsError
 		//	- BadRequestError

internal_workflow_client.go

@@ -137,15 +137,19 @@ func (wc *workflowClient) StartWorkflow(
 
 // SignalWorkflow signals a workflow in execution.
 func (wc *workflowClient) SignalWorkflow(workflowID string, runID string, signalName string, arg interface{}) error {
-	input, err := getHostEnvironment().encodeArg(arg)
-	if err != nil {
-		return err
+	var input []byte
+	if arg != nil {
+		var err error
+		if input, err = getHostEnvironment().encodeArg(arg); err != nil {
+			return err
+		}
 	}
+
 	request := &s.SignalWorkflowExecutionRequest{
 		Domain: common.StringPtr(wc.domain),
 		WorkflowExecution: &s.WorkflowExecution{
 			WorkflowId: common.StringPtr(workflowID),
-			RunId:      common.StringPtr(runID),
+			RunId:      getRunID(runID),
 		},
 		SignalName: common.StringPtr(signalName),
 		Input:      input,
@@ -166,7 +170,7 @@ func (wc *workflowClient) CancelWorkflow(workflowID string, runID string) error
 		Domain: common.StringPtr(wc.domain),
 		WorkflowExecution: &s.WorkflowExecution{
 			WorkflowId: common.StringPtr(workflowID),
-			RunId:      common.StringPtr(runID),
+			RunId:      getRunID(runID),
 		},
 		Identity: common.StringPtr(wc.identity),
 	}
@@ -187,7 +191,7 @@ func (wc *workflowClient) TerminateWorkflow(workflowID string, runID string, rea
 		Domain: common.StringPtr(wc.domain),
 		WorkflowExecution: &s.WorkflowExecution{
 			WorkflowId: common.StringPtr(workflowID),
-			RunId:      common.StringPtr(runID),
+			RunId:      getRunID(runID),
 		},
 		Reason:   common.StringPtr(reason),
 		Identity: common.StringPtr(wc.identity),
@@ -215,7 +219,7 @@ GetHistoryLoop:
 			Domain: common.StringPtr(wc.domain),
 			Execution: &s.WorkflowExecution{
 				WorkflowId: common.StringPtr(workflowID),
-				RunId:      common.StringPtr(runID),
+				RunId:      getRunID(runID),
 			},
 			NextPageToken: nextPageToken,
 		}
@@ -383,3 +387,11 @@ func (dc *domainClient) Update(name string, domainInfo *s.UpdateDomainInfo, doma
 			return err
 		}, serviceOperationRetryPolicy, isServiceTransientError)
 }
+
+func getRunID(runID string) *string {
+	if runID == "" {
+		// Cadence Server will pick current runID if provided empty.
+		return nil
+	}
+	return common.StringPtr(runID)
+}