WIP: Introduce CompressibleString

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 afb0dde5a7098e3586512891f6b6fafd91578856..a883765ef76e55ea5f520d7cd12cb14dd9f8dbe0 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8ValueCache.cpp
@@ -84,6 +84,27 @@ static v8::Local<v8::String> makeExternalString(v8::Isolate* isolate, const Stri
     return newString;
 }
 
+static v8::Local<v8::String> makeExternalString(v8::Isolate* isolate, const CompressableString& string)
+{
+    if (string.is8Bit()) {
+        WebCoreCompressableStringResource8* stringResource = new WebCoreCompressableStringResource8(string);
+        v8::Local<v8::String> newString;
+        if (!v8::String::NewExternalOneByte(isolate, stringResource).ToLocal(&newString)) {
+            delete stringResource;
+            return v8::String::Empty(isolate);
+        }
+        return newString;
+    }
+
+    WebCoreCompressableStringResource16* stringResource = new WebCoreCompressableStringResource16(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())
@@ -99,6 +120,14 @@ v8::Local<v8::String> StringCache::v8ExternalStringSlow(v8::Isolate* isolate, St
     return createStringAndInsertIntoCache(isolate, stringImpl);
 }
 
+v8::Local<v8::String> StringCache::v8ExternalStringSlow(v8::Isolate* isolate, const CompressableString& string)
+{
+    if (!string.length())
+        return v8::String::Empty(isolate);
+
+    return createStringAndInsertIntoCache(isolate, string);
+}
+
 void StringCache::setReturnValueFromStringSlow(v8::ReturnValue<v8::Value> returnValue, StringImpl* stringImpl)
 {
     if (!stringImpl->length()) {
@@ -136,6 +165,26 @@ v8::Local<v8::String> StringCache::createStringAndInsertIntoCache(v8::Isolate* i
     return newString;
 }
 
+v8::Local<v8::String> StringCache::createStringAndInsertIntoCache(v8::Isolate* isolate, const CompressableString& string)
+{
+    // ASSERT(!m_stringCache.Contains(stringImpl));
+    ASSERT(string.length());
+
+    v8::Local<v8::String> newString = makeExternalString(isolate, string);
+    ASSERT(!newString.IsEmpty());
+    ASSERT(newString->Length());
+
+    v8::UniquePersistent<v8::String> wrapper(isolate, newString);
+
+    // TODO(hajimehoshi): I'm not sure this ref is needed.
+    // string->ref();

[haraken, 2015/11/24 11:15:41]

This ref is needed. If you don't have the ref, who keeps the CompressableString
alive?

I guess that in your CL all the CompressableStrings are leaking because the
strings are never evicted from the V8PerIsolateData::m_compressableStrings.

+    wrapper.MarkIndependent();
+    // m_stringCache.Set(stringImpl, wrapper.Pass(), &m_lastV8String);

[haraken, 2015/11/24 11:15:41]

You need to put the CompressableString into the m_stringCache. Otherwise,
deref() is never called when V8 collects the wrapper of the CompressableString
(See line 34 - 56).

[hajimehoshi, 2015/11/26 10:49:13]

Hmm, I didn't know m_stringCache was the owner of String objects.

+    // m_lastStringImpl = stringImpl;
+
+    return newString;
+}
+
 void StringCache::InvalidateLastString()
 {
     m_lastStringImpl = nullptr;