Enable V8 Promises.

Source/bindings/v8/ScriptPromiseResolverWithContext.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ScriptPromiseResolverWithContext_h
 #define ScriptPromiseResolverWithContext_h
 
 #include "bindings/v8/NewScriptState.h"
 #include "bindings/v8/ScopedPersistent.h"
 #include "bindings/v8/ScriptPromise.h"
 #include "bindings/v8/ScriptPromiseResolver.h"
 #include "bindings/v8/V8Binding.h"
 #include "core/dom/ActiveDOMObject.h"
 #include "core/dom/ExecutionContext.h"
 #include "platform/Timer.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
 #include <v8.h>
 
 namespace WebCore {
 
 // This class wraps ScriptPromiseResolver and provides the following
 // functionalities in addition to ScriptPromiseResolver's.
 //  - A ScriptPromiseResolverWithContext retains a ScriptState. A caller
 //    can call resolve or reject from outside of a V8 context.
 //  - This class is an ActiveDOMObject and keeps track of the associated
 //    ExecutionContext state. When the ExecutionContext is suspended,
 //    resolve or reject will be delayed. When it is stopped, resolve or reject
 //    will be ignored.
+//
+// If you use ScriptPromiseResolverWithContext::resolve or reject from a
+// non script execution environment, you should NOT enter a v8 context
+// at the call site.
 class ScriptPromiseResolverWithContext FINAL : public ActiveDOMObject, public RefCounted<ScriptPromiseResolverWithContext> {
     WTF_MAKE_NONCOPYABLE(ScriptPromiseResolverWithContext);
 
 public:
     static PassRefPtr<ScriptPromiseResolverWithContext> create(NewScriptState* scriptState)
     {
         RefPtr<ScriptPromiseResolverWithContext> resolver = adoptRef(new ScriptPromiseResolverWithContext(scriptState));
         resolver->suspendIfNeeded();
         return resolver.release();
     }
 
+    virtual ~ScriptPromiseResolverWithContext();
+
     // Anything that can be passed to toV8Value can be passed to this function.
     template <typename T>
     void resolve(T value)
     {
-        if (m_state != Pending || !executionContext() || executionContext()->activeDOMObjectsAreStopped())
-            return;
-        m_state = Resolving;
-        NewScriptState::Scope scope(m_scriptState.get());
-        m_value.set(m_scriptState->isolate(), toV8Value(value));
-        if (!executionContext()->activeDOMObjectsAreSuspended())
-            resolveOrRejectImmediately(&m_timer);
+        resolveOrReject(value, Resolving);
     }
 
     // Anything that can be passed to toV8Value can be passed to this function.
     template <typename T>
     void reject(T value)
     {
-        if (m_state != Pending || !executionContext() || executionContext()->activeDOMObjectsAreStopped())
-            return;
-        m_state = Rejecting;
-        NewScriptState::Scope scope(m_scriptState.get());
-        m_value.set(m_scriptState->isolate(), toV8Value(value));
-        if (!executionContext()->activeDOMObjectsAreSuspended())
-            resolveOrRejectImmediately(&m_timer);
+        resolveOrReject(value, Rejecting);
     }
 
     NewScriptState* scriptState() { return m_scriptState.get(); }
 
     // Note that an empty ScriptPromise will be returned after resolve or
     // reject is called.
     ScriptPromise promise()
     {
         return m_resolver ? m_resolver->promise() : ScriptPromise();
     }
 
     NewScriptState* scriptState() const { return m_scriptState.get(); }
 
     // ActiveDOMObject implementation.
     virtual void suspend() OVERRIDE;
     virtual void resume() OVERRIDE;
     virtual void stop() OVERRIDE;
 
 private:
+    class RetainThis;

[jochen (gone - plz use gerrit), 2014/04/22 06:49:41]

we'd usually just ref() and deref()

[yhirano, 2014/04/22 07:49:05]

Done.

     enum ResolutionState {
         Pending,
         Resolving,
         Rejecting,
         ResolvedOrRejected,
     };
 
     explicit ScriptPromiseResolverWithContext(NewScriptState*);
 
     template<typename T>
@@ skipping 19 matching lines @@
 
     // const char* should use V8ValueTraits.
     v8::Handle<v8::Value> toV8Value(const char* value) { return V8ValueTraits<const char*>::toV8Value(value, m_scriptState->isolate()); }
 
     template<typename T, size_t inlineCapacity>
     v8::Handle<v8::Value> toV8Value(const Vector<T, inlineCapacity>& value)
     {
         return v8ArrayNoInline(value, m_scriptState->isolate());
     }
 
-    void resolveOrRejectImmediately(Timer<ScriptPromiseResolverWithContext>*);
+    template <typename T>
+    void resolveOrReject(T value, ResolutionState newState)
+    {
+        if (m_state != Pending || !executionContext() || executionContext()->activeDOMObjectsAreStopped())
+            return;
+        m_state = newState;
+        retainThis();
+
+        bool isInContext = m_scriptState->isolate()->InContext();
+        NewScriptState::Scope scope(m_scriptState.get());
+        m_value.set(m_scriptState->isolate(), toV8Value(value));
+        if (!executionContext()->activeDOMObjectsAreSuspended()) {
+            if (isInContext) {
+                resolveOrRejectImmediately();
+            } else {
+                m_timer.startOneShot(0, FROM_HERE);
+            }
+        }
+    }
+
+    void resolveOrRejectImmediately();
+    void onTimerFired(Timer<ScriptPromiseResolverWithContext>*);
+    void retainThis();
     void clear();
 
     ResolutionState m_state;
     const RefPtr<NewScriptState> m_scriptState;
     Timer<ScriptPromiseResolverWithContext> m_timer;
     RefPtr<ScriptPromiseResolver> m_resolver;
     ScopedPersistent<v8::Value> m_value;
+    // Retain this object during waiting for the timer.
+    RefPtr<RetainThis> m_retainThis;
 };
 
 } // namespace WebCore
 
 #endif // #ifndef ScriptPromiseResolverWithContext_h