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Add fast paths to WhenAny(IEnumerable) #38896

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Merged
merged 2 commits into from
Oct 11, 2020
Merged

Add fast paths to WhenAny(IEnumerable) #38896

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f9a1a06
Add fast paths to WhenAny(IEnumerable)
Bond-009 Jul 7, 2020
122309a
Remove cast from slow path for WhenAll and WhenAny
Bond-009 Jul 14, 2020
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31 changes: 25 additions & 6 deletions src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5472,15 +5472,15 @@ protected override void Cleanup()
/// </exception>
public static Task WhenAll(IEnumerable<Task> tasks)
{
// Take a more efficient path if tasks is actually an array
if (tasks is Task[] taskArray)
{
return WhenAll(taskArray);
}

// Skip a List allocation/copy if tasks is a collection
if (tasks is ICollection<Task> taskCollection)
{
// Take a more efficient path if tasks is actually an array
if (tasks is Task[] taskArray)
{
return WhenAll(taskArray);
}

int index = 0;
taskArray = new Task[taskCollection.Count];
foreach (Task task in tasks)
Expand Down Expand Up @@ -6080,6 +6080,25 @@ public void Invoke(Task completingTask)
/// </exception>
public static Task<Task> WhenAny(IEnumerable<Task> tasks)
{
// Skip a List allocation/copy if tasks is a collection
if (tasks is ICollection<Task> taskCollection)
{
// Take a more efficient path if tasks is actually an array
if (tasks is Task[] taskArray)
{
return WhenAny(taskArray);
}

int index = 0;
taskArray = new Task[taskCollection.Count];
foreach (Task task in tasks)
{
if (task == null) ThrowHelper.ThrowArgumentException(ExceptionResource.Task_MultiTaskContinuation_NullTask, ExceptionArgument.tasks);
taskArray[index++] = task;
}
return TaskFactory.CommonCWAnyLogic(taskArray);
}

if (tasks == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.tasks);

// Make a defensive copy, as the user may manipulate the tasks collection
Expand Down