Worker: Introduce an observation mechanism for WorkerThread termination

third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h

Index: third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h
diff --git a/third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h b/third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h
index 2e9cf96b263a16a41766da9a44797008aa58374b..1e2f3b5e7e6a494cb9e25d86a2386069ced5e2b0 100644
--- a/third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h
+++ b/third_party/WebKit/Source/modules/websockets/WorkerWebSocketChannel.h
@@ -32,6 +32,7 @@
 #define WorkerWebSocketChannel_h
 
 #include "bindings/core/v8/SourceLocation.h"
+#include "core/workers/WorkerThreadLifecycleObserver.h"
 #include "modules/websockets/WebSocketChannel.h"
 #include "modules/websockets/WebSocketChannelClient.h"
 #include "platform/heap/Handle.h"
@@ -83,16 +84,16 @@ public:
     DECLARE_VIRTUAL_TRACE();
 
     class Bridge;
-    // Allocated in the worker thread, but used in the main thread.
-    class Peer final : public GarbageCollectedFinalized<Peer>, public WebSocketChannelClient {
+    // Allocated and used in the main thread.
+    class Peer final : public GarbageCollectedFinalized<Peer>, public WebSocketChannelClient, public WorkerThreadLifecycleObserver {
         USING_GARBAGE_COLLECTED_MIXIN(Peer);
         WTF_MAKE_NONCOPYABLE(Peer);
     public:
-        Peer(Bridge*, PassRefPtr<WorkerLoaderProxy>, WebSocketChannelSyncHelper*);
+        Peer(Bridge*, PassRefPtr<WorkerLoaderProxy>, WebSocketChannelSyncHelper*, WorkerThreadContext*);
         ~Peer() override;
 
         // SourceLocation parameter may be shown when the connection fails.
-        void initialize(PassOwnPtr<SourceLocation>, ExecutionContext*);
+        bool initialize(PassOwnPtr<SourceLocation>, ExecutionContext*);
 
         void connect(const KURL&, const String& protocol);
         void sendTextAsCharVector(PassOwnPtr<Vector<char>>);
@@ -113,8 +114,11 @@ public:
         void didClose(ClosingHandshakeCompletionStatus, unsigned short code, const String& reason) override;
         void didError() override;
 
+        // WorkerThreadLifecycleObserver function.
+        void contextDestroyed() override;
+
     private:
-        Member<Bridge> m_bridge;
+        CrossThreadWeakPersistent<Bridge> m_bridge;

[haraken, 2016/06/10 00:45:36]

This changes the lifetime semantics. Before, it was a strong reference. Now, it
is a weak reference. Is this expected?

[yhirano, 2016/06/10 01:54:05]

It's intended. Previously Bridge and Peer referenced each other with Members.
That was OK because Members can handle reference cycles. Persistents cannot.

The WebSocket object in the worker has the websocket channel in the main thread
to communicate with the server. The back reference can be weak.

         RefPtr<WorkerLoaderProxy> m_loaderProxy;
         Member<WebSocketChannel> m_mainWebSocketChannel;
         Member<WebSocketChannelSyncHelper> m_syncHelper;
@@ -136,6 +140,8 @@ public:
         void fail(const String& reason, MessageLevel, PassOwnPtr<SourceLocation>);
         void disconnect();
 
+        void createPeerOnMainThread(PassOwnPtr<SourceLocation>, WorkerThreadContext*, ExecutionContext*);
+
         // Returns null when |disconnect| has already been called.
         WebSocketChannelClient* client() { return m_client; }
 
@@ -149,7 +155,7 @@ public:
         Member<WorkerGlobalScope> m_workerGlobalScope;
         RefPtr<WorkerLoaderProxy> m_loaderProxy;
         Member<WebSocketChannelSyncHelper> m_syncHelper;
-        Member<Peer> m_peer;
+        CrossThreadPersistent<Peer> m_peer;
     };
 
 private: