/// <summary>
/// Get how many number of synchronous tasks in our tracking list.
/// </summary>
private int CountOfDependingSynchronousTasks()
{
int count = 0;
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
count++;
existingTaskTracking = existingTaskTracking.Next;
}
return(count);
}
/// <summary>
/// Removes all synchronous tasks we applies to a dependent task, after the relationship is removed.
/// </summary>
/// <param name="child">The original dependent task</param>
private void RemoveDependingSynchronousTaskFromChild(JoinableTask child)
{
Requires.NotNull(child, nameof(child));
Assumes.True(Monitor.IsEntered(this.owner.Context.SyncContextLock));
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
child.RemoveDependingSynchronousTask(existingTaskTracking.SynchronousTask);
existingTaskTracking = existingTaskTracking.Next;
}
}
/// <summary>
/// Check whether a task is being tracked in our tracking list.
/// </summary>
private bool IsDependingSynchronousTask(JoinableTask syncTask)
{
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
if (existingTaskTracking.SynchronousTask == syncTask)
{
return(true);
}
existingTaskTracking = existingTaskTracking.Next;
}
return(false);
}
/// <summary>
/// Gets a value indicating whether the main thread is waiting for the task's completion
/// This method is expected to be used with the JTF lock.
/// </summary>
internal bool HasMainThreadSynchronousTaskWaiting()
{
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
if ((existingTaskTracking.SynchronousTask.State & JoinableTask.JoinableTaskFlags.SynchronouslyBlockingMainThread) == JoinableTask.JoinableTaskFlags.SynchronouslyBlockingMainThread)
{
return(true);
}
existingTaskTracking = existingTaskTracking.Next;
}
return(false);
}
/// <summary>
/// Remove all synchronous tasks tracked by the this task.
/// This is called when this task is completed
/// </summary>
private void CleanupDependingSynchronousTask()
{
if (this.dependingSynchronousTaskTracking != null)
{
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
this.dependingSynchronousTaskTracking = null;
if (this.childOrJoinedJobs != null)
{
var childrenTasks = this.childOrJoinedJobs.Select(item => item.Key).ToList();
while (existingTaskTracking != null)
{
RemoveDependingSynchronousTaskFrom(childrenTasks, existingTaskTracking.SynchronousTask, false);
existingTaskTracking = existingTaskTracking.Next;
}
}
}
}
/// <summary>
/// Remove all synchronous tasks tracked by the this task.
/// This is called when this task is completed.
/// This method is expected to be used with the JTF lock.
/// </summary>
internal void OnTaskCompleted()
{
if (this.dependingSynchronousTaskTracking != null)
{
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
this.dependingSynchronousTaskTracking = null;
if (this.childDependentNodes != null)
{
var childrenTasks = new List <IJoinableTaskDependent>(this.childDependentNodes.Keys);
while (existingTaskTracking != null)
{
RemoveDependingSynchronousTaskFrom(childrenTasks, existingTaskTracking.SynchronousTask, false);
existingTaskTracking = existingTaskTracking.Next;
}
}
}
}
/// <summary>
/// Calculate the collection of events we need trigger after we enqueue a request.
/// </summary>
/// <param name="forMainThread">True if we want to find tasks to process the main thread queue. Otherwise tasks to process the background queue.</param>
/// <returns>The collection of synchronous tasks we need notify.</returns>
private List <JoinableTask> GetDependingSynchronousTasks(bool forMainThread)
{
Assumes.True(Monitor.IsEntered(this.owner.Context.SyncContextLock));
var tasksNeedNotify = new List <JoinableTask>(this.CountOfDependingSynchronousTasks());
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
var syncTask = existingTaskTracking.SynchronousTask;
bool syncTaskInOnMainThread = (syncTask.state & JoinableTaskFlags.SynchronouslyBlockingMainThread) == JoinableTaskFlags.SynchronouslyBlockingMainThread;
if (forMainThread == syncTaskInOnMainThread)
{
// Only synchronous tasks are in the list, so we don't need do further check for the CompletingSynchronously flag
tasksNeedNotify.Add(syncTask);
}
existingTaskTracking = existingTaskTracking.Next;
}
return(tasksNeedNotify);
}
/// <summary>
/// Applies all synchronous tasks tracked by this task to a new child/dependent task.
/// </summary>
/// <param name="child">The new child task.</param>
/// <returns>Pairs of synchronous tasks we need notify and the event source triggering it, plus the number of pending events.</returns>
private List <PendingNotification> AddDependingSynchronousTaskToChild(JoinableTask child)
{
Requires.NotNull(child, nameof(child));
Assumes.True(Monitor.IsEntered(this.owner.Context.SyncContextLock));
var tasksNeedNotify = new List <PendingNotification>(this.CountOfDependingSynchronousTasks());
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
int totalEventNumber = 0;
var eventTriggeringTask = child.AddDependingSynchronousTask(existingTaskTracking.SynchronousTask, ref totalEventNumber);
if (eventTriggeringTask != null)
{
tasksNeedNotify.Add(new PendingNotification(existingTaskTracking.SynchronousTask, eventTriggeringTask, totalEventNumber));
}
existingTaskTracking = existingTaskTracking.Next;
}
return(tasksNeedNotify);
}
/// <summary>
/// Remove a synchronous task from the tracking list of this task.
/// </summary>
/// <param name="task">The synchronous task need be removed</param>
/// <param name="reachableTasks">
/// If it is not null, it will contain all task which can track the synchronous task. We will ignore reference count in that case.
/// </param>
/// <param name="remainingDependentTasks">This will retain the tasks which still tracks the synchronous task.</param>
private void RemoveDependingSynchronousTask(JoinableTask task, HashSet <JoinableTask> reachableTasks, ref HashSet <JoinableTask> remainingDependentTasks)
{
Requires.NotNull(task, nameof(task));
DependentSynchronousTask previousTaskTracking = null;
DependentSynchronousTask currentTaskTracking = this.dependingSynchronousTaskTracking;
bool removed = false;
while (currentTaskTracking != null)
{
if (currentTaskTracking.SynchronousTask == task)
{
if (--currentTaskTracking.ReferenceCount > 0)
{
if (reachableTasks != null)
{
if (!reachableTasks.Contains(this))
{
currentTaskTracking.ReferenceCount = 0;
}
}
}
if (currentTaskTracking.ReferenceCount == 0)
{
removed = true;
if (previousTaskTracking != null)
{
previousTaskTracking.Next = currentTaskTracking.Next;
}
else
{
this.dependingSynchronousTaskTracking = currentTaskTracking.Next;
}
}
if (reachableTasks == null)
{
if (removed)
{
if (remainingDependentTasks != null)
{
remainingDependentTasks.Remove(this);
}
}
else
{
if (remainingDependentTasks == null)
{
remainingDependentTasks = new HashSet <JoinableTask>();
}
remainingDependentTasks.Add(this);
}
}
break;
}
previousTaskTracking = currentTaskTracking;
currentTaskTracking = currentTaskTracking.Next;
}
if (removed && this.childOrJoinedJobs != null)
{
foreach (var item in this.childOrJoinedJobs)
{
item.Key.RemoveDependingSynchronousTask(task, reachableTasks, ref remainingDependentTasks);
}
}
}
/// <summary>
/// Tracks a new synchronous task for this task.
/// A synchronous task is a task blocking a thread and waits it to be completed. We may want the blocking thread
/// to process events from this task.
/// </summary>
/// <param name="task">The synchronous task</param>
/// <param name="totalEventsPending">The total events need be processed</param>
/// <returns>The task causes us to trigger the event of the synchronous task, so it can process new events. Null means we don't need trigger any event</returns>
private JoinableTask AddDependingSynchronousTask(JoinableTask task, ref int totalEventsPending)
{
Requires.NotNull(task, nameof(task));
Assumes.True(Monitor.IsEntered(this.owner.Context.SyncContextLock));
if (this.IsCompleted)
{
return(null);
}
if (this.IsCompleteRequested)
{
// A completed task might still have pending items in the queue.
int pendingCount = this.GetPendingEventCountForTask(task);
if (pendingCount > 0)
{
totalEventsPending += pendingCount;
return(this);
}
return(null);
}
DependentSynchronousTask existingTaskTracking = this.dependingSynchronousTaskTracking;
while (existingTaskTracking != null)
{
if (existingTaskTracking.SynchronousTask == task)
{
existingTaskTracking.ReferenceCount++;
return(null);
}
existingTaskTracking = existingTaskTracking.Next;
}
int pendingItemCount = this.GetPendingEventCountForTask(task);
JoinableTask eventTriggeringTask = null;
if (pendingItemCount > 0)
{
totalEventsPending += pendingItemCount;
eventTriggeringTask = this;
}
// For a new synchronous task, we need apply it to our child tasks.
DependentSynchronousTask newTaskTracking = new DependentSynchronousTask(task)
{
Next = this.dependingSynchronousTaskTracking,
};
this.dependingSynchronousTaskTracking = newTaskTracking;
if (this.childOrJoinedJobs != null)
{
foreach (var item in this.childOrJoinedJobs)
{
var childTiggeringTask = item.Key.AddDependingSynchronousTask(task, ref totalEventsPending);
if (eventTriggeringTask == null)
{
eventTriggeringTask = childTiggeringTask;
}
}
}
return(eventTriggeringTask);
}
