public async Task <IEnumerable <ActivityRecord> > ExecuteWorkflowAsync(WorkflowExecutionContext workflowContext, ActivityRecord activity)
{
var workflowType = workflowContext.WorkflowType;
var scheduled = new Stack <ActivityRecord>();
var blocking = new List <ActivityRecord>();
var isResuming = workflowContext.Status == WorkflowStatus.Resuming;
var isFirstPass = true;
workflowContext.Status = WorkflowStatus.Executing;
scheduled.Push(activity);
while (scheduled.Count > 0)
{
activity = scheduled.Pop();
var activityContext = workflowContext.GetActivity(activity.ActivityId);
// Signal every activity that the activity is about to be executed.
var cancellationToken = new CancellationToken();
await InvokeActivitiesAsync(workflowContext, x => x.Activity.OnActivityExecutingAsync(workflowContext, activityContext, cancellationToken));
if (cancellationToken.IsCancellationRequested)
{
// Activity is aborted.
workflowContext.Status = WorkflowStatus.Aborted;
break;
}
IList <string> outcomes = new List <string>(0);
try
{
ActivityExecutionResult result;
if (!isResuming)
{
// Execute the current activity.
result = await activityContext.Activity.ExecuteAsync(workflowContext, activityContext);
}
else
{
// Resume the current activity.
result = await activityContext.Activity.ResumeAsync(workflowContext, activityContext);
isResuming = false;
}
if (result.IsHalted)
{
if (isFirstPass)
{
// Resume immediately when this is the first pass.
result = await activityContext.Activity.ResumeAsync(workflowContext, activityContext);
isFirstPass = false;
outcomes = result.Outcomes;
if (result.IsHalted)
{
// Block on this activity.
blocking.Add(activity);
}
}
else
{
// Block on this activity.
blocking.Add(activity);
continue;
}
}
else
{
outcomes = result.Outcomes;
}
}
catch (Exception ex)
{
_logger.LogError(ex, "An unhandled error occurred while executing an activity. Workflow ID: '{WorkflowTypeId}'. Activity: '{ActivityId}', '{ActivityName}'. Putting the workflow in the faulted state.", workflowType.Id, activityContext.ActivityRecord.ActivityId, activityContext.ActivityRecord.Name);
workflowContext.Fault(ex, activityContext);
return(blocking.Distinct());
}
// Signal every activity that the activity is executed.
await InvokeActivitiesAsync(workflowContext, x => x.Activity.OnActivityExecutedAsync(workflowContext, activityContext));
foreach (var outcome in outcomes)
{
// Look for next activity in the graph.
var transition = workflowType.Transitions.FirstOrDefault(x => x.SourceActivityId == activity.ActivityId && x.SourceOutcomeName == outcome);
if (transition != null)
{
var destinationActivity = workflowContext.WorkflowType.Activities.SingleOrDefault(x => x.ActivityId == transition.DestinationActivityId);
scheduled.Push(destinationActivity);
}
}
isFirstPass = false;
}
// Apply Distinct() as two paths could block on the same activity.
var blockingActivities = blocking.Distinct().ToList();
workflowContext.Status = blockingActivities.Any() || workflowContext.Workflow.BlockingActivities.Any() ? WorkflowStatus.Halted : WorkflowStatus.Finished;
foreach (var blockingActivity in blockingActivities)
{
// Workflows containing event activities could end up being blocked on the same activity.
if (!workflowContext.Workflow.BlockingActivities.Any(x => x.ActivityId == blockingActivity.ActivityId))
{
workflowContext.Workflow.BlockingActivities.Add(BlockingActivity.FromActivity(blockingActivity));
}
}
return(blockingActivities);
}
