/// <summary>Initializes a new continuation.</summary>
/// <param name="task">The task to be activated.</param>
/// <param name="options">The continuation options.</param>
/// <param name="scheduler">The scheduler to use for the continuation.</param>
internal StandardTaskContinuation(Task task, TaskContinuationOptions options, TaskScheduler scheduler)
{
Debug.Assert(task != null, "TaskContinuation ctor: task is null");
Debug.Assert(scheduler != null, "TaskContinuation ctor: scheduler is null");
m_task = task;
m_options = options;
m_taskScheduler = scheduler;
if (DebuggerSupport.LoggingOn)
DebuggerSupport.TraceOperationCreation(CausalityTraceLevel.Required, m_task, "Task.ContinueWith: " + task.m_action, 0);
DebuggerSupport.AddToActiveTasks(m_task);
}
/// <summary>Invokes the continuation for the target completion task.</summary>
/// <param name="completedTask">The completed task.</param>
/// <param name="bCanInlineContinuationTask">Whether the continuation can be inlined.</param>
internal override void Run(Task completedTask, bool bCanInlineContinuationTask)
{
Debug.Assert(completedTask != null);
Debug.Assert(completedTask.IsCompleted, "ContinuationTask.Run(): completedTask not completed");
// Check if the completion status of the task works with the desired
// activation criteria of the TaskContinuationOptions.
TaskContinuationOptions options = m_options;
bool isRightKind =
completedTask.IsCompletedSuccessfully ?
(options & TaskContinuationOptions.NotOnRanToCompletion) == 0 :
(completedTask.IsCanceled ?
(options & TaskContinuationOptions.NotOnCanceled) == 0 :
(options & TaskContinuationOptions.NotOnFaulted) == 0);
// If the completion status is allowed, run the continuation.
Task continuationTask = m_task;
if (isRightKind)
{
if (!continuationTask.IsCanceled && DebuggerSupport.LoggingOn)
{
// Log now that we are sure that this continuation is being ran
DebuggerSupport.TraceOperationRelation(CausalityTraceLevel.Important, continuationTask, CausalityRelation.AssignDelegate);
}
continuationTask.m_taskScheduler = m_taskScheduler;
// Either run directly or just queue it up for execution, depending
// on whether synchronous or asynchronous execution is wanted.
if (bCanInlineContinuationTask && // inlining is allowed by the caller
(options & TaskContinuationOptions.ExecuteSynchronously) != 0) // synchronous execution was requested by the continuation's creator
{
InlineIfPossibleOrElseQueue(continuationTask, needsProtection: true);
}
else
{
try { continuationTask.ScheduleAndStart(needsProtection: true); }
catch (TaskSchedulerException)
{
// No further action is necessary -- ScheduleAndStart() already transitioned the
// task to faulted. But we want to make sure that no exception is thrown from here.
}
}
}
// Otherwise, the final state of this task does not match the desired
// continuation activation criteria; cancel it to denote this.
else
{
continuationTask.InternalCancel(false);
}
}
