ServiceWorker: Bypass resolving a promise when ExecutionContext is gone

Source/bindings/core/v8/CallbackPromiseAdapter.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 42 matching lines @@
 //
 //        // Since promise resolving is done as an async task, it's not
 //        // guaranteed that the script context has seen the promise resolve
 //        // immediately after calling onSuccess/onError. You can use the
 //        // ScriptPromise from the resolver to schedule a task that executes
 //        // after resolving:
 //        ScriptState::Scope scope(resolver->scriptState());
 //        resolver->promise().then(...);
 //    }
 //
+//    // Called when aborting to resolve/reject a promise due to an empty
+//    // execution context.
+//    static void dispose(blink::WebMyClass* webInstance) {
+//        // delete as appropriate, but often it's just:
+//        delete webInstance;
+//    }
+//
 // Now when calling into a WebKit API that requires a WebCallbacks<blink::WebMyClass, blink::WebMyClass>*:
 //
 //    // call signature: callSomeMethod(WebCallbacks<MyClass, MyClass>* callbacks)
 //    webObject->callSomeMethod(new CallbackPromiseAdapter<MyClass, MyClass>(resolver, scriptExecutionContext));
 //
 // Note that this class does not manage its own lifetime. In this
 // example that ownership of the WebCallbacks instance is being passed
 // in and it is up to the callee to free the WebCallbacks instace.
 template<typename S, typename T>
 class CallbackPromiseAdapter FINAL : public blink::WebCallbacks<typename S::WebType, typename T::WebType> {
 public:
     CallbackPromiseAdapter(PassRefPtr<ScriptPromiseResolver> resolver)
         : m_resolver(resolver)
     {
     }
     virtual ~CallbackPromiseAdapter() { }
 
     virtual void onSuccess(typename S::WebType* result) OVERRIDE
     {
+        if (!m_resolver || !m_resolver->executionContext()) {

[yhirano, 2014/07/18 09:00:02]

m_resolver cannot be null (you can add ASSERT(m_resolver) in the constructor if
you prefer).
!m_resolver->executionContext() ||
m_resolver->executionContext()->activeDOMObjectsAreStopped() is better.

[nhiroki, 2014/07/18 10:28:56]

Done.

+            S::dispose(result);
+            return;
+        }
         m_resolver->resolve(S::from(m_resolver.get(), result));
     }
+
     virtual void onError(typename T::WebType* error) OVERRIDE
     {
+        if (!m_resolver || !m_resolver->executionContext()) {

[yhirano, 2014/07/18 09:00:02]

ditto

[nhiroki, 2014/07/18 10:28:56]

Done.

+            T::dispose(error);
+            return;
+        }
         m_resolver->reject(T::from(m_resolver.get(), error));
     }
+
 private:
     RefPtr<ScriptPromiseResolver> m_resolver;
     WTF_MAKE_NONCOPYABLE(CallbackPromiseAdapter);
 };
 
 } // namespace WebCore
 
 #endif