Experimental CompressibleString UMA

third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp b/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
index 9c902c2811dcd4401d5d6e5cb19832f297d71a21..a39f489d461df5b2b02387098d2ddb05ee2c0f6b 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
@@ -54,6 +54,29 @@ void StringCacheMapTraits::OnWeakCallback(const v8::WeakCallbackInfo<WeakCallbac
     V8PerIsolateData::from(data.GetIsolate())->stringCache()->InvalidateLastString();
 }
 
+
+CompressibleStringCacheMapTraits::MapType* CompressibleStringCacheMapTraits::MapFromWeakCallbackInfo(
+    const v8::WeakCallbackInfo<WeakCallbackDataType>& data)
+{
+    return &(V8PerIsolateData::from(data.GetIsolate())->stringCache()->m_compressibleStringCache);
+}
+
+void CompressibleStringCacheMapTraits::Dispose(
+    v8::Isolate* isolate, v8::Global<v8::String> value, CompressibleStringImpl* key)
+{
+    key->deref();
+}
+
+void CompressibleStringCacheMapTraits::DisposeWeak(const v8::WeakCallbackInfo<WeakCallbackDataType>& data)
+{
+    data.GetParameter()->deref();
+}
+
+void CompressibleStringCacheMapTraits::OnWeakCallback(const v8::WeakCallbackInfo<WeakCallbackDataType>& data)
+{
+}
+
+
 void StringCache::dispose()
 {
     // The MapType::Dispose callback calls StringCache::InvalidateLastString,
@@ -83,6 +106,27 @@ static v8::Local<v8::String> makeExternalString(v8::Isolate* isolate, const Stri
     return newString;
 }
 
+static v8::Local<v8::String> makeExternalString(v8::Isolate* isolate, const CompressibleString& string)
+{
+    if (string.is8Bit()) {
+        WebCoreCompressibleStringResource8* stringResource = new WebCoreCompressibleStringResource8(string);
+        v8::Local<v8::String> newString;
+        if (!v8::String::NewExternalOneByte(isolate, stringResource).ToLocal(&newString)) {
+            delete stringResource;
+            return v8::String::Empty(isolate);
+        }
+        return newString;
+    }
+
+    WebCoreCompressibleStringResource16* stringResource = new WebCoreCompressibleStringResource16(string);
+    v8::Local<v8::String> newString;
+    if (!v8::String::NewExternalTwoByte(isolate, stringResource).ToLocal(&newString)) {
+        delete stringResource;
+        return v8::String::Empty(isolate);
+    }
+    return newString;
+}
+
 v8::Local<v8::String> StringCache::v8ExternalStringSlow(v8::Isolate* isolate, StringImpl* stringImpl)
 {
     if (!stringImpl->length())
@@ -98,6 +142,18 @@ v8::Local<v8::String> StringCache::v8ExternalStringSlow(v8::Isolate* isolate, St
     return createStringAndInsertIntoCache(isolate, stringImpl);
 }
 
+v8::Local<v8::String> StringCache::v8ExternalStringSlow(v8::Isolate* isolate, const CompressibleString& string)
+{
+    if (!string.length())
+        return v8::String::Empty(isolate);
+
+    CompressibleStringCacheMapTraits::MapType::PersistentValueReference cachedV8String = m_compressibleStringCache.GetReference(string.impl());
+    if (!cachedV8String.IsEmpty())
+        return cachedV8String.NewLocal(isolate);
+
+    return createStringAndInsertIntoCache(isolate, string);
+}
+
 void StringCache::setReturnValueFromStringSlow(v8::ReturnValue<v8::Value> returnValue, StringImpl* stringImpl)
 {
     if (!stringImpl->length()) {
@@ -135,6 +191,31 @@ v8::Local<v8::String> StringCache::createStringAndInsertIntoCache(v8::Isolate* i
     return newString;
 }
 
+v8::Local<v8::String> StringCache::createStringAndInsertIntoCache(v8::Isolate* isolate, const CompressibleString& string)
+{
+    CompressibleStringImpl* stringImpl = string.impl();
+
+    ASSERT(!m_compressibleStringCache.Contains(stringImpl));
+    ASSERT(stringImpl->originalLength());
+
+    v8::Local<v8::String> newString = makeExternalString(isolate, string);
+    ASSERT(!newString.IsEmpty());
+    ASSERT(newString->Length());
+
+    v8::UniquePersistent<v8::String> wrapper(isolate, newString);
+
+    stringImpl->ref();
+    wrapper.MarkIndependent();
+    // CompressibleStringImpl objects are NOT cached on |m_stringCache| or
+    // |m_lastStringImpl|. It's because if even one objects holds a StringImpl
+    // object in a CompressibleStringImpl, uncompressed string will exists even
+    // when compressing the string.
+    CompressibleStringCacheMapTraits::MapType::PersistentValueReference unused;
+    m_compressibleStringCache.Set(stringImpl, wrapper.Pass(), &unused);
+
+    return newString;
+}
+
 void StringCache::InvalidateLastString()
 {
     m_lastStringImpl = nullptr;