Source/bindings/v8/V8ValueCache.cpp

/*
 * Copyright (C) 2009 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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/V8ValueCache.h"

#include "bindings/v8/V8Binding.h"
#include "bindings/v8/V8Utilities.h"
#include "core/dom/WebCoreMemoryInstrumentation.h"
#include "wtf/MemoryInstrumentationHashMap.h"
#include "wtf/MemoryInstrumentationSequence.h"
#include "wtf/text/StringHash.h"

namespace WTF {

template<> struct SequenceMemoryInstrumentationTraits<v8::String*> {
    template <typename I> static void reportMemoryUsage(I, I, MemoryClassInfo&) { }
};

}

namespace WebCore {

v8::Local<v8::String> StringCache::makeExternalString(const String& string)
{
    if (string.is8Bit()) {
        WebCoreStringResource8* stringResource = new WebCoreStringResource8(string);
        v8::Local<v8::String> newString = v8::String::NewExternal(stringResource);
        if (newString.IsEmpty())
            delete stringResource;
        return newString;
    }

    WebCoreStringResource16* stringResource = new WebCoreStringResource16(string);
    v8::Local<v8::String> newString = v8::String::NewExternal(stringResource);
    if (newString.IsEmpty())
        delete stringResource;
    return newString;
}

void StringCache::makeWeakCallback(v8::Isolate* isolate, v8::Persistent<v8::String>* wrapper, StringImpl* stringImpl)
{
    V8PerIsolateData::current()->stringCache()->remove(stringImpl);
    wrapper->Dispose(isolate);
    stringImpl->deref();
}

void StringCache::remove(StringImpl* stringImpl) 
{
    ASSERT(m_stringCache.contains(stringImpl));
    m_stringCache.remove(stringImpl);
    // Make sure that already disposed m_lastV8String is not used in
    // StringCache::v8ExternalString().
    clearOnGC();
}

v8::Handle<v8::String> StringCache::v8ExternalStringSlow(StringImpl* stringImpl, v8::Isolate* isolate)
{
    if (!stringImpl->length())
        return v8::String::Empty(isolate);

    UnsafePersistent<v8::String> cachedV8String = m_stringCache.get(stringImpl);
    if (cachedV8String.isWeak()) {
        m_lastStringImpl = stringImpl;
        m_lastV8String = cachedV8String;
        return cachedV8String.newLocal(isolate);
    }

    return createStringAndInsertIntoCache(stringImpl, isolate);
}

v8::Local<v8::String> StringCache::createStringAndInsertIntoCache(StringImpl* stringImpl, v8::Isolate* isolate)
{
    v8::Local<v8::String> newString = makeExternalString(String(stringImpl));
    if (newString.IsEmpty()) {
        return newString;
    }

    v8::Persistent<v8::String> wrapper(isolate, newString);

    stringImpl->ref();
    wrapper.MarkIndependent(isolate);
    wrapper.MakeWeak(stringImpl, &makeWeakCallback);
    m_lastV8String = UnsafePersistent<v8::String>(wrapper);
    m_stringCache.set(stringImpl, m_lastV8String);

    m_lastStringImpl = stringImpl;
    return newString;
}

void StringCache::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
{
    MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::Binding);
    info.addMember(m_stringCache, "stringCache");
    info.ignoreMember(m_lastV8String);
    info.addMember(m_lastStringImpl, "lastStringImpl");
}

} // namespace WebCore