WIP: Introduce CompressibleString

third_party/WebKit/Source/bindings/core/v8/V8StringResource.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
@@ skipping 21 matching lines @@
 namespace blink {
 
 template<class StringClass> struct StringTraits {
     static const StringClass& fromStringResource(WebCoreStringResourceBase*);
     template <typename V8StringTrait>
     static StringClass fromV8String(v8::Local<v8::String>, int);
 };
 
 template<>
 struct StringTraits<String> {
-    static const String& fromStringResource(WebCoreStringResourceBase* resource)
+    static String fromStringResource(WebCoreStringResourceBase* resource)
     {
         return resource->webcoreString();
     }
     template <typename V8StringTrait>
     static String fromV8String(v8::Local<v8::String>, int);
 };
 
 template<>
 struct StringTraits<AtomicString> {
-    static const AtomicString& fromStringResource(WebCoreStringResourceBase* resource)
+    static AtomicString fromStringResource(WebCoreStringResourceBase* resource)
     {
         return resource->atomicString();
     }
     template <typename V8StringTrait>
     static AtomicString fromV8String(v8::Local<v8::String>, int);
 };
 
 struct V8StringTwoBytesTrait {
     typedef UChar CharType;
     ALWAYS_INLINE static void write(v8::Local<v8::String> v8String, CharType* buffer, int length)
@@ skipping 38 matching lines @@
 
 template<typename StringType>
 StringType v8StringToWebCoreString(v8::Local<v8::String> v8String, ExternalMode external)
 {
     {
         // This portion of this function is very hot in certain Dromeao benchmarks.
         v8::String::Encoding encoding;
         v8::String::ExternalStringResourceBase* resource = v8String->GetExternalStringResourceBase(&encoding);
         if (LIKELY(!!resource)) {
             WebCoreStringResourceBase* base;
-            if (encoding == v8::String::ONE_BYTE_ENCODING)
-                base = static_cast<WebCoreStringResource8*>(resource);
-            else
-                base = static_cast<WebCoreStringResource16*>(resource);
+            if (UNLIKELY(resource->isCompressable())) {
+                if (encoding == v8::String::ONE_BYTE_ENCODING)
+                    base = static_cast<WebCoreCompressableStringResource8*>(resource);
+                else
+                    base = static_cast<WebCoreCompressableStringResource16*>(resource);
+            } else {
+                if (encoding == v8::String::ONE_BYTE_ENCODING)
+                    base = static_cast<WebCoreStringResource8*>(resource);
+                else
+                    base = static_cast<WebCoreStringResource16*>(resource);
+            }
             return StringTraits<StringType>::fromStringResource(base);
         }
     }
 
     int length = v8String->Length();
     if (UNLIKELY(!length))
         return StringType("");
 
     bool oneByte = v8String->ContainsOnlyOneByte();
     StringType result(oneByte ? StringTraits<StringType>::template fromV8String<V8StringOneByteTrait>(v8String, length) : StringTraits<StringType>::template fromV8String<V8StringTwoBytesTrait>(v8String, length));
@@ skipping 11 matching lines @@
             delete stringResource;
     }
     return result;
 }
 
 // Explicitly instantiate the above template with the expected parameterizations,
 // to ensure the compiler generates the code; otherwise link errors can result in GCC 4.4.
 template String v8StringToWebCoreString<String>(v8::Local<v8::String>, ExternalMode);
 template AtomicString v8StringToWebCoreString<AtomicString>(v8::Local<v8::String>, ExternalMode);
 
+template String v8StringToWebCoreString2<String>(v8::Local<v8::String>, ExternalMode);

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

Do we need this template?

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

Sorry but this was a test code. Removed.

+
+template<typename StringType>
+StringType v8StringToWebCoreString2(v8::Local<v8::String> v8String, ExternalMode external)

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

Ditto.

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

Done.

+{
+    {
+        // This portion of this function is very hot in certain Dromeao benchmarks.
+        v8::String::Encoding encoding;
+        v8::String::ExternalStringResourceBase* resource = v8String->GetExternalStringResourceBase(&encoding);
+        if (LIKELY(!!resource)) {
+            // TODO(hajimehoshi): What if resource is a compressablestring???
+            WebCoreStringResourceBase* base;
+            if (encoding == v8::String::ONE_BYTE_ENCODING)
+                base = static_cast<WebCoreStringResource8*>(resource);
+            else
+                base = static_cast<WebCoreStringResource16*>(resource);
+            return StringTraits<StringType>::fromStringResource(base);
+        }
+    }
+
+    int length = v8String->Length();
+    if (UNLIKELY(!length))
+        return StringType("");
+
+    bool oneByte = v8String->ContainsOnlyOneByte();
+    StringType result(oneByte ? StringTraits<StringType>::template fromV8String<V8StringOneByteTrait>(v8String, length) : StringTraits<StringType>::template fromV8String<V8StringTwoBytesTrait>(v8String, length));
+
+    if (external != Externalize || !v8String->CanMakeExternal())
+        return result;
+
+    if (result.is8Bit()) {
+        WebCoreStringResource8* stringResource = new WebCoreStringResource8(result);
+        if (UNLIKELY(!v8String->MakeExternal(stringResource)))
+            delete stringResource;
+    } else {
+        WebCoreStringResource16* stringResource = new WebCoreStringResource16(result);
+        if (UNLIKELY(!v8String->MakeExternal(stringResource)))
+            delete stringResource;
+    }
+    return result;
+}
+
 // Fast but non thread-safe version.
 String int32ToWebCoreStringFast(int value)
 {
     // Caching of small strings below is not thread safe: newly constructed AtomicString
     // are not safely published.
     ASSERT(isMainThread());
 
     // Most numbers used are <= 100. Even if they aren't used there's very little cost in using the space.
     const int kLowNumbers = 100;
     DEFINE_STATIC_LOCAL(Vector<AtomicString>, lowNumbers, (kLowNumbers + 1));
@@ skipping 13 matching lines @@
 
 String int32ToWebCoreString(int value)
 {
     // If we are on the main thread (this should always true for non-workers), call the faster one.
     if (isMainThread())
         return int32ToWebCoreStringFast(value);
     return String::number(value);
 }
 
 } // namespace blink