[AI Task] [Tizen.Multimedia.Remoting] Add RunContinuationsAsynchronously to async TCS by JoonghyunCho · Pull Request #7696 · Samsung/TizenFX

JoonghyunCho · 2026-06-15T00:47:52Z

Summary

Tizen.Multimedia.Remoting had 8 TaskCompletionSource<T> sites that omitted TaskCreationOptions.RunContinuationsAsynchronously. These tcs instances are completed on native callback threads or external event-manager callback threads (e.g. CommandCompleted += ...), so by default their continuations run inline on the completing thread. That can occupy the native callback thread with arbitrary user continuation code (blocking subsequent callbacks / harming ABI stability) and risks deadlock when the awaiter re-enters the same SynchronizationContext.

This is the Remoting counterpart of the same known-critical pattern fixed for Tizen.Network.WiFi in #7620. WebRTC/WebRTCSignalingServer.cs:165 already specified the option correctly and is left unchanged.

Changes

src/Tizen.Multimedia.Remoting/ScreenMirroring/ScreenMirroring.cs — RunAsync tcs (1 site)
src/Tizen.Multimedia.Remoting/WebRTC/WebRTC.cs — StartAsync, CreateOfferAsync, CreateAnswerAsync tcs (3 sites)
src/Tizen.Multimedia.Remoting/MediaController/MediaController.cs — RequestAsync(Command), RequestAsync(Command, Bundle) tcs (2 sites)
src/Tizen.Multimedia.Remoting/MediaController/MediaControlServer.cs — RequestAsync(clientId, command), RequestAsync(clientId, command, Bundle) tcs (2 sites)

Each change adds TaskCreationOptions.RunContinuationsAsynchronously to the TaskCompletionSource<T> constructor. No public API signatures change; the returned Task is unchanged. Behavior is preserved — moving continuations to the ThreadPool does not alter await semantics.

Mode

Refactoring

Verification

Build: passed (dotnet build -c Release on Tizen.Multimedia.Remoting, 0 errors)
Tests: N/A (no behavior change; internal async completion semantics only)
Benchmark: skipped (sdb error: no device connected — sdb devices lists none). Manual benchmark verification required.

Fixes #7639

…nc TCS The 8 TaskCompletionSource sites in ScreenMirroring, WebRTC, MediaController and MediaControlServer complete on native/event-manager callback threads. Without RunContinuationsAsynchronously their continuations run inline on the completing thread, which can occupy native callback threads and risk deadlock on SynchronizationContext re-entry. Mirrors the WiFi fix in #7620. Fixes #7639 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gemini-code-assist

Code Review

This pull request updates several instances of TaskCompletionSource to use TaskCreationOptions.RunContinuationsAsynchronously across the remoting and multimedia modules. The review feedback suggests simplifying RunAsync in ScreenMirroring.cs by returning the Task from Task.Run directly instead of wrapping it in a redundant TaskCompletionSource<bool>. Additionally, multiple await Task.Yield(); calls in WebRTC.cs are now redundant due to the asynchronous continuation guarantee and should be removed to avoid unnecessary context switching.

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gemini-code-assist · 2026-06-15T00:48:51Z

        private Task RunAsync(Func<IntPtr, ScreenMirroringErrorCode> func, string failMessage)
        {
-            var tcs = new TaskCompletionSource<bool>();
+            var tcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);


The RunAsync method can be simplified by returning the Task from Task.Run directly, rather than wrapping it in a redundant TaskCompletionSource<bool>. Since RunAsync returns a non-generic Task, the bool result is ignored anyway.

Refactoring this avoids the allocation of the TaskCompletionSource and its associated task, and simplifies error propagation.

For example:

private Task RunAsync(Func<IntPtr, ScreenMirroringErrorCode> func, string failMessage) { return Task.Run(() => { var ret = func(Handle); if (ret != ScreenMirroringErrorCode.None) { throw ret.AsException(failMessage); } }); }

🤖 [AI Review]
Addressed in 64f1117.

gemini-code-assist · 2026-06-15T00:48:51Z

            ValidateWebRTCState(WebRTCState.Idle);

-            var tcs = new TaskCompletionSource<bool>();
+            var tcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);


Now that TaskCreationOptions.RunContinuationsAsynchronously is specified on the TaskCompletionSource, the continuation of await tcs.Task is guaranteed to execute asynchronously on the thread pool.

As a result, the await Task.Yield(); on line 196 is redundant and can be safely removed to avoid unnecessary context switching and thread rescheduling.

🤖 [AI Review]
Addressed in 64f1117.

gemini-code-assist · 2026-06-15T00:48:51Z

            ValidateWebRTCState(WebRTCState.Negotiating, WebRTCState.Playing);

-            var tcsSdpCreated = new TaskCompletionSource<string>();
+            var tcsSdpCreated = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);


Now that TaskCreationOptions.RunContinuationsAsynchronously is specified on tcsSdpCreated, the continuation of await tcsSdpCreated.Task is guaranteed to execute asynchronously on the thread pool.

Therefore, the await Task.Yield(); on line 261 is redundant and can be safely removed to avoid unnecessary context switching and thread rescheduling.

🤖 [AI Review]
Addressed in 64f1117.

gemini-code-assist · 2026-06-15T00:48:51Z

            ValidateWebRTCState(WebRTCState.Negotiating, WebRTCState.Playing);

-            var tcsSdpCreated = new TaskCompletionSource<string>();
+            var tcsSdpCreated = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);


Now that TaskCreationOptions.RunContinuationsAsynchronously is specified on tcsSdpCreated, the continuation of await tcsSdpCreated.Task is guaranteed to execute asynchronously on the thread pool.

Therefore, the await Task.Yield(); on line 300 is redundant and can be safely removed to avoid unnecessary context switching and thread rescheduling.

🤖 [AI Review]
Addressed in 64f1117.

Simplify ScreenMirroring.RunAsync to return Task.Run directly (drop redundant TaskCompletionSource), and remove now-redundant await Task.Yield() after awaiting RunContinuationsAsynchronously TCS in WebRTC.StartAsync/CreateOfferAsync/CreateAnswerAsync. Applied-Human-Comments: 3410546783,3410546787,3410546789,3410546792 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

JoonghyunCho · 2026-06-17T12:04:50Z

🤖 [AI Review]
Addressed review feedback in commit 64f1117. Summary: simplified ScreenMirroring.RunAsync to return Task.Run(...) directly (dropping the redundant TaskCompletionSource<bool>), and removed the now-redundant await Task.Yield(); after the RunContinuationsAsynchronously TCS awaits in WebRTC.StartAsync, CreateOfferAsync, and CreateAnswerAsync. Built Tizen.Multimedia.Remoting (Release) — 0 errors.

TizenAPI-Bot · 2026-06-17T12:09:48Z

Internal API Changed

Added: 17, Removed: 0, Changed: 0

Added

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture::SourceSub()

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ Tizen.NUI.Gesture/SourceSubType

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Finger

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Fingernail

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::HandFlat

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::HandSide

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Knuckle

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::None

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Palm

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::PenTip

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Remocon

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Trackball

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Trackpad

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::Trackpoint

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::VirtualKeyboard

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::VirtualMouse

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ static Tizen.NUI.Gesture/SourceSubType Tizen.NUI.Gesture/SourceSubType::VirtualRemocon

JoonghyunCho requested a review from hsgwon as a code owner June 15, 2026 00:47

JoonghyunCho added the ai-task label Jun 15, 2026

github-actions Bot added the API15 label Jun 15, 2026

gemini-code-assist Bot reviewed Jun 15, 2026

View reviewed changes

TizenAPI-Bot added the Internal API Changed label Jun 17, 2026

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[AI Task] [Tizen.Multimedia.Remoting] Add RunContinuationsAsynchronously to async TCS#7696

[AI Task] [Tizen.Multimedia.Remoting] Add RunContinuationsAsynchronously to async TCS#7696
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ai-task/issue-7639

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JoonghyunCho commented Jun 15, 2026

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