/// <summary>
/// Handles internal <see cref="TemporalClient.SignalSync"/> workflow signals.
/// </summary>
/// <param name="request">The request message.</param>
/// <returns>The reply message.</returns>
internal async Task <WorkflowSignalInvokeReply> OnSyncSignalAsync(WorkflowSignalInvokeRequest request)
{
await SyncContext.Clear;
Covenant.Requires <ArgumentNullException>(request != null, nameof(request));
try
{
WorkflowBase.CallContext.Value = WorkflowCallContext.Signal;
var workflow = GetWorkflow(request.ContextId);
if (workflow != null)
{
Workflow.Current = workflow.Workflow; // Initialize the ambient workflow information.
// The signal arguments should be just a single [SyncSignalCall] that specifies
// the target signal and also includes its encoded arguments.
var signalCallArgs = TemporalHelper.BytesToArgs(JsonDataConverter.Instance, request.SignalArgs, new Type[] { typeof(SyncSignalCall) });
var signalCall = (SyncSignalCall)signalCallArgs[0];
var signalMethod = workflow.Workflow.MethodMap.GetSignalMethod(signalCall.TargetSignal);
var userSignalArgs = TemporalHelper.BytesToArgs(Client.DataConverter, signalCall.UserArgs, signalMethod.GetParameterTypes());
Workflow.Current.SignalId = signalCall.SignalId;
// Create a dictionary with the signal method arguments keyed by parameter name.
var args = new Dictionary <string, object>();
var parameters = signalMethod.GetParameters();
for (int i = 0; i < parameters.Length; i++)
{
args.Add(parameters[i].Name, userSignalArgs[i]);
}
// Persist the state that the signal status queries will examine.
// We're also going to use the presence of this state to make
// synchronous signal calls idempotent by ensuring that we'll
// only call the signal method once per signal ID.
//
// Note that it's possible that a record has already exists.
var signalStatus = workflow.SetSignalStatus(signalCall.SignalId, args, out var newSignal);
if (newSignal && signalMethod != null)
{
Workflow.Current = workflow.Workflow; // Initialize the ambient workflow information for workflow library code.
var result = (object)null;
var exception = (Exception)null;
// Execute the signal method (if there is one).
try
{
if (TemporalHelper.IsTask(signalMethod.ReturnType))
{
// Method returns [Task]: AKA void.
await(Task)(signalMethod.Invoke(workflow, userSignalArgs));
}
else
{
// Method returns [Task<T>]: AKA a result.
// $note(jefflill):
//
// I would have liked to do something like this:
//
// result = await (Task<object>)(method.Invoke(workflow, userArgs));
//
// here, but that not going to work because the Task<T>
// being returned won't typically be a Task<object>,
// so the cast will fail.
//
// So instead, I'm going to use reflection to obtain the
// Task.Result property and then obtain the result from that.
var task = (Task)(signalMethod.Invoke(workflow, userSignalArgs));
var resultProperty = task.GetType().GetProperty("Result");
await task;
result = resultProperty.GetValue(task);
}
}
catch (Exception e)
{
exception = e;
}
if (exception?.GetType() == typeof(WaitForSignalReplyException))
{
// This will be thrown by synchronous signal handlers that marshalled
// the signal to the workflow logic. We're going to ignore the signal
// method result in this case and NOT MARK THE SIGNAL AS COMPLETED.
}
else
{
var syncSignalStatus = workflow.GetSignalStatus(signalCall.SignalId);
if (syncSignalStatus != null)
{
if (exception == null)
{
syncSignalStatus.Result = Client.DataConverter.ToData(result);
}
else
{
log.LogError(exception);
syncSignalStatus.Error = SyncSignalException.GetError(exception);
}
syncSignalStatus.Completed = true;
}
else
{
Covenant.Assert(false); // This should never happen.
}
}
return(new WorkflowSignalInvokeReply()
{
RequestId = request.RequestId
});
}
else
{
return(new WorkflowSignalInvokeReply()
{
Error = new EntityNotExistsException($"Workflow type [{workflow.GetType().FullName}] does not define a signal handler for [signalName={request.SignalName}].").ToTemporalError()
});
}
}
else
{
// I don't believe we'll ever land here because that would mean that
// Temporal sends signals to a workflow that hasn't started running
// on a worker (which wouldn't make sense).
//
// We're going go ahead and send a reply, just in case.
return(new WorkflowSignalInvokeReply());
}
}
catch (Exception e)
{
log.LogError(e);
return(new WorkflowSignalInvokeReply()
{
Error = new TemporalError(e)
});
}
finally
{
WorkflowBase.CallContext.Value = WorkflowCallContext.None;
}
}