[ABANDONED] Implement ThenableCoercions for AP2 Promises

Source/bindings/v8/ThenableCoercions.cpp

+/*
+ * 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
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "bindings/v8/ThenableCoercions.h"
+
+namespace WebCore {
+
+PassOwnPtr<ThenableCoercions> ThenableCoercions::create()
+{
+    return adoptPtr(new ThenableCoercions());
+}
+
+ThenableCoercions::ThenableCoercions()
+    : m_entries()
+    , m_entriesToDelete()
+    , m_entriesListGuarded(false)
+{
+}
+
+ThenableCoercions::~ThenableCoercions()
+{
+    Entry* entry = m_entries.head();
+    while (entry) {
+        Entry* nextEntry = entry->next();
+        delete entry;
+        entry = nextEntry;
+    }
+}
+
+bool ThenableCoercions::has(v8::Handle<v8::Object> thenable)
+{
+    return !get(thenable).IsEmpty();
+}
+
+v8::Handle<v8::Object> ThenableCoercions::get(v8::Handle<v8::Object> thenable)
+{
+    // GuardEntriesListAgainstGC guarantees that |m_entries| linked list won't
+    // be corrupt when GC collects the weak references during the iteration.
+    // If the entry's thenable is collected during the iteration,
+    // its thenable and promise become empty, but node is not unlinked from the
+    // |m_entries|.
+    // Nodes will be destroyed when GuardEntriesListAgainstGC is destroyed.
+    GuardEntriesListAgainstGC guard(this);
+    Entry* entry = m_entries.head();
+    while (entry) {
+        v8::Local<v8::Object> storedThenable = entry->thenable();
+        if (!storedThenable.IsEmpty() && storedThenable->SameValue(thenable))

[yusukesuzuki, 2013/09/26 02:44:14]

To follow the WeakMap spec of ES6 draft, use SameValue instead of StrictEquals.
SameValue algorithm is exposed by V8 in this CL[1].

[1]: https://codereview.chromium.org/24360017/

+            return entry->promise();
+        entry = entry->next();
+    }
+    return v8::Handle<v8::Object>();
+}
+
+void ThenableCoercions::set(v8::Handle<v8::Object> thenable, v8::Handle<v8::Object> promise, v8::Isolate* isolate)
+{
+    GuardEntriesListAgainstGC guard(this);
+    Entry* entry = Entry::create(thenable, promise, this, isolate);
+    m_entries.append(entry);
+}
+
+void ThenableCoercions::tryToDelete(ThenableCoercions::Entry* entry)
+{
+    if (m_entriesListGuarded) {
+        m_entriesToDelete.append(entry);
+        return;
+    }
+    deleteInternal(entry);
+}
+
+void ThenableCoercions::deleteInternal(Entry* entry)
+{
+    m_entries.remove(entry);
+    delete entry;
+}
+
+ThenableCoercions::Entry::Entry(v8::Handle<v8::Object> thenable, v8::Handle<v8::Object> promise, ThenableCoercions* thenableCoercions, v8::Isolate* isolate)
+    : m_next(0)
+    , m_prev(0)
+    , m_thenable(isolate, thenable)
+    , m_promise(isolate, promise)
+    , m_thenableCoercions(thenableCoercions)
+    , m_isolate(isolate)
+{
+    m_thenable.makeWeak(this, &makeWeakCallback);
+}
+
+void ThenableCoercions::Entry::makeWeakCallback(v8::Isolate* isolate, v8::Persistent<v8::Object>* thenable, ThenableCoercions::Entry* entry)
+{
+    entry->m_thenableCoercions->tryToDelete(entry);
+    entry->m_thenable.clear();
+    entry->m_promise.clear();
+}
+
+ThenableCoercions::GuardEntriesListAgainstGC::GuardEntriesListAgainstGC(ThenableCoercions* thenableCoercions)
+    : m_thenableCoercions(thenableCoercions)
+{
+    thenableCoercions->m_entriesListGuarded = true;
+}
+
+ThenableCoercions::GuardEntriesListAgainstGC::~GuardEntriesListAgainstGC()
+{
+    for (size_t i = 0; i < m_thenableCoercions->m_entriesToDelete.size(); ++i)
+        m_thenableCoercions->deleteInternal(m_thenableCoercions->m_entriesToDelete[i]);
+    m_thenableCoercions->m_entriesToDelete.clear();
+    m_thenableCoercions->m_entriesListGuarded = false;
+}
+
+} // namespace WebCore