NEW TEST(276140@main): [ MacOS WK1 Debug ] media/media-source/worker/media-managedmse-worker.html is a constant crash

LayoutTests/media/media-source/worker/media-managedmse-worker-expected.txt

@@ -1,4 +1,5 @@
 
+EXPECTED (ManagedMediaSource.canConstructInDedicatedWorker == 'true') OK
 RUN(video.disableRemotePlayback = true)
 received handle message: [object MediaSourceHandle] OK
 info message from worker: sourceopen event received OK

LayoutTests/media/media-source/worker/media-managedmse-worker.html

@@ -7,18 +7,23 @@
     window.addEventListener('load', async event => {
         findMediaElement();
 
+        testExpected('ManagedMediaSource.canConstructInDedicatedWorker', true);
         const worker = new Worker('worker.js');
         worker.onmessage = msg => {
             switch (msg.data.topic) {
-                case 'handle':
+            case 'handle':
                 logResult(true, 'received handle message: ' + msg.data.arg);
                 video.srcObject = msg.data.arg;
                 break;
-                case 'info':
+            case 'info':
                 logResult(true, 'info message from worker: ' + msg.data.arg);
                 endTest();
                 break;
-                default:
+            case 'error':
+                logResult(false, 'error message from worker: ' + msg.data.arg);
+                endTest();
+                break;
+            default:
                 logResult(false, 'error: Unrecognized topic in message from worker');
                 break;
             }

LayoutTests/media/media-source/worker/worker.js

@@ -2,15 +2,22 @@ function logToMain(msg) {
     postMessage({topic: 'info', arg: msg});
 }
 
-onmessage = (e) => {
-    const ms = new ManagedMediaSource();
-    const handle = ms.handle;
+function logErrorToMain(msg) {
+    postMessage({topic: 'error', arg: msg});
+}
 
-    ms.onsourceopen = () => {
-        logToMain("sourceopen event received");
-    };
-    // Transfer the MediaSourceHandle to the main thread for use in attaching to
-    // the main thread media element that will play the content being buffered
-    // here in the worker.
-    postMessage({topic: 'handle', arg: handle}, [handle]);
+onmessage = (e) => {
+    try {
+        const ms = new ManagedMediaSource();
+        const handle = ms.handle;
+        ms.onsourceopen = () => {
+            logToMain("sourceopen event received");
+        };
+        // Transfer the MediaSourceHandle to the main thread for use in attaching to
+        // the main thread media element that will play the content being buffered
+        // here in the worker.
+        postMessage({topic: 'handle', arg: handle}, [handle]);
+    } catch (e) {
+        logErrorToMain('MSE not supported');
+    }
 };

LayoutTests/platform/mac-wk1/TestExpectations

@@ -2823,8 +2823,6 @@ webkit.org/b/270385 [ Sonoma+ ] fast/images/jpegxl-with-color-profile.html [ Ima
 
 webkit.org/b/259485 [ Ventura ] http/tests/media/hls/track-in-band-multiple-cues.html [ Skip ]
 
-webkit.org/b/271323 [ Debug ] media/media-source/worker/media-managedmse-worker.html [ Skip ]
-
 # webkit.org/b/270199 [ MacOS WK1 Debug ] fast/frames/lots-of-iframes.html and fast/frames/lots-of-objects.html are consistent/flaky timeouts
 [ Debug ] fast/frames/lots-of-iframes.html [ Pass Timeout ]
 [ Debug ] fast/frames/lots-of-objects.html [ Pass Timeout ]

LayoutTests/platform/mac-wk1/media/media-source/worker/media-managedmse-worker-expected.txt

@@ -0,0 +1,6 @@
+
+EXPECTED (ManagedMediaSource.canConstructInDedicatedWorker == 'true'), OBSERVED 'false' FAIL
+RUN(video.disableRemotePlayback = true)
+error message from worker: MSE not supported FAIL
+END OF TEST
+

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -4300,6 +4300,7 @@ MediaSourceInWorkerEnabled:
   humanReadableName: "MediaSource in a Worker"
   humanReadableDescription: "MediaSource in a Worker"
   condition: ENABLE(MEDIA_SOURCE_IN_WORKERS)
+  exposed: [ WebCore, WebKit ]
   defaultValue:
     WebKitLegacy:
       default: false

Source/WebCore/Modules/mediasource/MediaSource.cpp

@@ -54,6 +54,8 @@
 #endif
 #include "MediaSourcePrivate.h"
 #include "MediaSourceRegistry.h"
+#include "MediaStrategy.h"
+#include "PlatformStrategies.h"
 #include "Quirks.h"
 #include "ScriptExecutionContext.h"
 #include "Settings.h"
@@ -1579,7 +1581,7 @@ bool MediaSource::enabledForContext(ScriptExecutionContext& context)
     UNUSED_PARAM(context);
 #if ENABLE(MEDIA_SOURCE_IN_WORKERS)
     if (context.isWorkerGlobalScope())
-        return context.settingsValues().mediaSourceInWorkerEnabled;
+        return context.settingsValues().mediaSourceInWorkerEnabled && platformStrategies()->mediaStrategy().hasThreadSafeMediaSourceSupport();
 #endif
 
     ASSERT(context.isDocument());
@@ -1601,7 +1603,7 @@ Ref<MediaSourceHandle> MediaSource::handle()
 
 bool MediaSource::canConstructInDedicatedWorker(ScriptExecutionContext& context)
 {
-    return context.settingsValues().mediaSourceInWorkerEnabled;
+    return context.settingsValues().mediaSourceInWorkerEnabled && platformStrategies()->mediaStrategy().hasThreadSafeMediaSourceSupport();
 }
 
 #endif

Source/WebCore/platform/MediaStrategy.cpp

@@ -51,6 +51,11 @@ void MediaStrategy::resetMediaEngines()
     m_mockMediaSourceEnabled = false;
 }
 
+bool MediaStrategy::hasThreadSafeMediaSourceSupport() const
+{
+    return false;
+}
+
 #if ENABLE(MEDIA_SOURCE)
 void MediaStrategy::enableMockMediaSource()
 {

Source/WebCore/platform/MediaStrategy.h

@@ -44,6 +44,7 @@ class WEBCORE_EXPORT MediaStrategy {
 #endif
     virtual std::unique_ptr<NowPlayingManager> createNowPlayingManager() const;
     void resetMediaEngines();
+    virtual bool hasThreadSafeMediaSourceSupport() const;
 #if ENABLE(MEDIA_SOURCE)
     virtual void enableMockMediaSource();
     bool mockMediaSourceEnabled() const;

Source/WebCore/platform/PlatformStrategies.h

@@ -25,6 +25,8 @@
 
 #pragma once
 
+#include <mutex>
+
 namespace WebCore {
 
 class BlobRegistry;
@@ -53,8 +55,9 @@ class PlatformStrategies {
 
     MediaStrategy& mediaStrategy()
     {
-        if (!m_mediaStrategy)
+        std::call_once(m_onceKeyForMediaStrategies, [&] {
             m_mediaStrategy = createMediaStrategy();
+        });
         return *m_mediaStrategy;
     }
 
@@ -89,6 +92,7 @@ class PlatformStrategies {
 
     LoaderStrategy* m_loaderStrategy { };
     PasteboardStrategy* m_pasteboardStrategy { };
+    std::once_flag m_onceKeyForMediaStrategies;
     MediaStrategy* m_mediaStrategy { };
     BlobRegistry* m_blobRegistry { };
 

Source/WebKit/WebProcess/GPU/media/WebMediaStrategy.cpp

@@ -55,6 +55,7 @@ WebMediaStrategy::~WebMediaStrategy() = default;
 Ref<WebCore::AudioDestination> WebMediaStrategy::createAudioDestination(WebCore::AudioIOCallback& callback, const String& inputDeviceId,
     unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate)
 {
+    ASSERT(isMainRunLoop());
 #if ENABLE(GPU_PROCESS)
     if (m_useGPUProcess)
         return WebCore::SharedAudioDestination::create(callback, numberOfOutputChannels, sampleRate, [inputDeviceId, numberOfInputChannels, numberOfOutputChannels, sampleRate] (WebCore::AudioIOCallback& callback) {
@@ -67,6 +68,7 @@ Ref<WebCore::AudioDestination> WebMediaStrategy::createAudioDestination(WebCore:
 
 std::unique_ptr<WebCore::NowPlayingManager> WebMediaStrategy::createNowPlayingManager() const
 {
+    ASSERT(isMainRunLoop());
 #if ENABLE(GPU_PROCESS)
     if (m_useGPUProcess) {
         class NowPlayingInfoForGPUManager : public WebCore::NowPlayingManager {
@@ -88,9 +90,19 @@ std::unique_ptr<WebCore::NowPlayingManager> WebMediaStrategy::createNowPlayingMa
     return WebCore::MediaStrategy::createNowPlayingManager();
 }
 
+bool WebMediaStrategy::hasThreadSafeMediaSourceSupport() const
+{
+#if ENABLE(GPU_PROCESS)
+    return m_useGPUProcess;
+#else
+    return false;
+#endif
+}
+
 #if ENABLE(MEDIA_SOURCE)
 void WebMediaStrategy::enableMockMediaSource()
 {
+    ASSERT(isMainRunLoop());
 #if USE(AVFOUNDATION)
     WebCore::DeprecatedGlobalSettings::setAVFoundationEnabled(false);
 #endif

Source/WebKit/WebProcess/GPU/media/WebMediaStrategy.h

@@ -26,6 +26,7 @@
 #pragma once
 
 #include <WebCore/MediaStrategy.h>
+#include <atomic>
 
 namespace WebKit {
 
@@ -43,12 +44,13 @@ class WebMediaStrategy final : public WebCore::MediaStrategy {
         const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate) override;
 #endif
     std::unique_ptr<WebCore::NowPlayingManager> createNowPlayingManager() const final;
+    bool hasThreadSafeMediaSourceSupport() const final;
 #if ENABLE(MEDIA_SOURCE)
     void enableMockMediaSource() final;
 #endif
 
 #if ENABLE(GPU_PROCESS)
-    bool m_useGPUProcess { false };
+    std::atomic<bool> m_useGPUProcess { false };
 #endif
 };