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// <copyright>
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
namespace System.ServiceModel.Dispatcher
{
using System;
using System.Diagnostics;
using System.Reflection;
using System.Runtime;
using System.Security;
using System.ServiceModel.Description;
using System.ServiceModel.Diagnostics;
using System.Threading.Tasks;
using Threading;
/// <summary>
/// An invoker used when some operation contract has a return value of Task or its generic counterpart (Task of T)
/// </summary>
internal class TaskMethodInvoker : IOperationInvoker
{
private const string ResultMethodName = "Result";
private readonly MethodInfo taskMethod;
private InvokeDelegate invokeDelegate;
private int inputParameterCount;
private int outputParameterCount;
private MethodInfo taskTResultGetMethod;
private bool isGenericTask;
public TaskMethodInvoker(MethodInfo taskMethod, Type taskType)
{
if (taskMethod == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("taskMethod"));
}
this.taskMethod = taskMethod;
if (taskType != ServiceReflector.VoidType)
{
this.taskTResultGetMethod = ((PropertyInfo)taskMethod.ReturnType.GetMember(ResultMethodName)[0]).GetGetMethod();
this.isGenericTask = true;
}
}
public bool IsSynchronous
{
get { return false; }
}
public MethodInfo TaskMethod
{
get { return this.taskMethod; }
}
public object[] AllocateInputs()
{
EnsureIsInitialized();
return EmptyArray<object>.Allocate(this.inputParameterCount);
}
public object Invoke(object instance, object[] inputs, out object[] outputs)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new NotImplementedException());
}
public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state)
{
return ToApm(InvokeAsync(instance, inputs), callback, state);
}
public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result)
{
if (instance == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.GetString(SR.SFxNoServiceObject)));
}
object returnVal = null;
bool callFailed = true;
bool callFaulted = false;
ServiceModelActivity activity = null;
Activity boundOperation = null;
try
{
AsyncMethodInvoker.GetActivityInfo(ref activity, ref boundOperation);
Task<Tuple<object, object[]>> invokeTask = result as Task<Tuple<object, object[]>>;
if (invokeTask == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.SFxInvalidCallbackIAsyncResult));
}
AggregateException ae = null;
Tuple<object, object[]> tuple = null;
Task task = null;
if (invokeTask.IsFaulted)
{
Fx.Assert(invokeTask.Exception != null, "Task.IsFaulted guarantees non-null exception.");
ae = invokeTask.Exception;
}
else
{
Fx.Assert(invokeTask.IsCompleted, "Task.Result is expected to be completed");
tuple = invokeTask.Result;
task = tuple.Item1 as Task;
if (task == null)
{
outputs = tuple.Item2;
return null;
}
if (task.IsFaulted)
{
Fx.Assert(task.Exception != null, "Task.IsFaulted guarantees non-null exception.");
ae = task.Exception;
}
}
if (ae != null && ae.InnerException != null)
{
if (ae.InnerException is FaultException)
{
// If invokeTask.IsFaulted we produce the 'callFaulted' behavior below.
// Any other exception will retain 'callFailed' behavior.
callFaulted = true;
callFailed = false;
}
if (ae.InnerException is SecurityException)
{
DiagnosticUtility.TraceHandledException(ae.InnerException, TraceEventType.Warning);
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(AuthorizationBehavior.CreateAccessDeniedFaultException());
}
invokeTask.GetAwaiter().GetResult();
}
// Task cancellation without an exception indicates failure but we have no
// additional information to provide. Accessing Task.Result will throw a
// TaskCanceledException. For consistency between void Tasks and Task<T>,
// we detect and throw here.
if (task.IsCanceled)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new TaskCanceledException(task));
}
outputs = tuple.Item2;
returnVal = this.isGenericTask ? this.taskTResultGetMethod.Invoke(task, Type.EmptyTypes) : null;
callFailed = false;
return returnVal;
}
finally
{
if (boundOperation != null)
{
((IDisposable)boundOperation).Dispose();
}
ServiceModelActivity.Stop(activity);
AsyncMethodInvoker.StopOperationInvokeTrace(callFailed, callFaulted, this.TaskMethod.Name);
AsyncMethodInvoker.StopOperationInvokePerformanceCounters(callFailed, callFaulted, this.TaskMethod.Name);
}
}
private async Task<Tuple<object, object[]>> InvokeAsync(object instance, object[] inputs)
{
EnsureIsInitialized();
if (instance == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.GetString(SR.SFxNoServiceObject)));
}
if (inputs == null)
{
if (this.inputParameterCount > 0)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.GetString(SR.SFxInputParametersToServiceNull, this.inputParameterCount)));
}
}
else if (inputs.Length != this.inputParameterCount)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.GetString(SR.SFxInputParametersToServiceInvalid, this.inputParameterCount, inputs.Length)));
}
object[] outputs = EmptyArray.Allocate(this.outputParameterCount);
AsyncMethodInvoker.StartOperationInvokePerformanceCounters(this.taskMethod.Name);
object returnValue;
ServiceModelActivity activity = null;
Activity boundActivity = null;
try
{
AsyncMethodInvoker.CreateActivityInfo(ref activity, ref boundActivity);
AsyncMethodInvoker.StartOperationInvokeTrace(this.taskMethod.Name);
if (DiagnosticUtility.ShouldUseActivity)
{
string activityName = SR.GetString(SR.ActivityExecuteMethod, this.taskMethod.DeclaringType.FullName, this.taskMethod.Name);
ServiceModelActivity.Start(activity, activityName, ActivityType.ExecuteUserCode);
}
OperationContext.EnableAsyncFlow();
returnValue = this.invokeDelegate(instance, inputs, outputs);
if (returnValue == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("task");
}
var returnValueTask = returnValue as Task;
if (returnValueTask != null)
{
// Only return once the task has completed
await returnValueTask;
}
return Tuple.Create(returnValue, outputs);
}
catch (SecurityException e)
{
DiagnosticUtility.TraceHandledException(e, TraceEventType.Warning);
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(AuthorizationBehavior.CreateAccessDeniedFaultException());
}
catch (Exception e)
{
TraceUtility.TraceUserCodeException(e, this.taskMethod);
throw;
}
finally
{
OperationContext.DisableAsyncFlow();
if (boundActivity != null)
{
((IDisposable)boundActivity).Dispose();
}
ServiceModelActivity.Stop(activity);
}
}
// Helper method when implementing an APM wrapper around a Task based async method which returns a result.
// In the BeginMethod method, you would call use ToApm to wrap a call to MethodAsync:
// return MethodAsync(params).ToApm(callback, state);
// In the EndMethod, you would use ToApmEnd<TResult> to ensure the correct exception handling
// This will handle throwing exceptions in the correct place and ensure the IAsyncResult contains the provided
// state object
private static Task<TResult> ToApm<TResult>(Task<TResult> task, AsyncCallback callback, object state)
{
// When using APM, the returned IAsyncResult must have the passed in state object stored in AsyncState. This
// is so the callback can regain state. If the incoming task already holds the state object, there's no need
// to create a TaskCompletionSource to ensure the returned (IAsyncResult)Task has the right state object.
// This is a performance optimization for this special case.
if (task.AsyncState == state)
{
if (callback != null)
{
task.ContinueWith((antecedent, obj) =>
{
AsyncCallback callbackObj = (AsyncCallback)obj;
callbackObj(antecedent);
}, callback, CancellationToken.None, TaskContinuationOptions.HideScheduler, TaskScheduler.Default);
}
return task;
}
// Need to create a TaskCompletionSource so that the returned Task object has the correct AsyncState value.
var tcs = new TaskCompletionSource<TResult>(state);
var continuationState = Tuple.Create(tcs, callback);
task.ContinueWith((antecedent, obj) =>
{
Tuple<TaskCompletionSource<TResult>, AsyncCallback> tuple = (Tuple<TaskCompletionSource<TResult>, AsyncCallback>)obj;
TaskCompletionSource<TResult> tcsObj = tuple.Item1;
AsyncCallback callbackObj = tuple.Item2;
if (antecedent.IsFaulted)
{
tcsObj.TrySetException(antecedent.Exception.InnerException);
}
else if (antecedent.IsCanceled)
{
tcsObj.TrySetCanceled();
}
else
{
tcsObj.TrySetResult(antecedent.Result);
}
if (callbackObj != null)
{
callbackObj(tcsObj.Task);
}
}, continuationState, CancellationToken.None, TaskContinuationOptions.HideScheduler, TaskScheduler.Default);
return tcs.Task;
}
private void EnsureIsInitialized()
{
if (this.invokeDelegate == null)
{
// Only pass locals byref because InvokerUtil may store temporary results in the byref.
// If two threads both reference this.count, temporary results may interact.
int inputParameterCount;
int outputParameterCount;
InvokeDelegate invokeDelegate = new InvokerUtil().GenerateInvokeDelegate(this.taskMethod, out inputParameterCount, out outputParameterCount);
this.inputParameterCount = inputParameterCount;
this.outputParameterCount = outputParameterCount;
this.invokeDelegate = invokeDelegate; // must set this last due to ----
}
}
}
}
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