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Fix a few minor issues in Channels #32916
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Just to better conform to the typical spelling.
…t SyncContext
When {Unsafe}OnCompleted is called on an AsyncOperation in Channels, without ConfigureAwait(false), we look to see if there's a current non-default SynchronizationContext, and if there isn't, then a current non-default TaskScheduler. That's stored for later when the operation is completed. However, if as OnCompleted is being called the operation is completed, then rather than using this captured context or scheduler later, the continuation is immediately queued to the appropriate context. When that happens, if the current SynchronizationContext was non-null but still the default (an instance of the base class), we're incorrectly ignoring whatever TaskScheduler may have been present, and end up queueing to the thread pool rather than to that scheduler.
The fix is just to ensure that, in that case, we don't pay attention to the default SynchronizationContext. This does so and adds a test.
Validate that, when there's both a non-default SyncContext and a non-default TaskScheduler, we prefer the SyncContext.
tarekgh
approved these changes
Oct 19, 2018
picenka21
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to picenka21/runtime
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Feb 18, 2022
* Fix a few XML comments
* Rename internal Dequeue<T> to Deque<T>
Just to better conform to the typical spelling.
* Fix includes ordering in Channels project file
* Fix continuation scheduling with non-default TaskScheduler and default SyncContext
When {Unsafe}OnCompleted is called on an AsyncOperation in Channels, without ConfigureAwait(false), we look to see if there's a current non-default SynchronizationContext, and if there isn't, then a current non-default TaskScheduler. That's stored for later when the operation is completed. However, if as OnCompleted is being called the operation is completed, then rather than using this captured context or scheduler later, the continuation is immediately queued to the appropriate context. When that happens, if the current SynchronizationContext was non-null but still the default (an instance of the base class), we're incorrectly ignoring whatever TaskScheduler may have been present, and end up queueing to the thread pool rather than to that scheduler.
The fix is just to ensure that, in that case, we don't pay attention to the default SynchronizationContext. This does so and adds a test.
* Add a test with both non-default SyncContext and TaskScheduler set
Validate that, when there's both a non-default SyncContext and a non-default TaskScheduler, we prefer the SyncContext.
Commit migrated from dotnet/corefx@207a50b
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cc: @tarekgh