Experimental CompressibleString UMA

third_party/WebKit/Source/bindings/core/v8/V8StringResource.h

 /*
  * 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 10 matching lines @@
  * 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.
  */
 
 #ifndef V8StringResource_h
 #define V8StringResource_h
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/CoreExport.h"
+#include "platform/text/CompressibleString.h"
 #include "wtf/Allocator.h"
 #include "wtf/Threading.h"
 #include "wtf/text/AtomicString.h"
 #include <v8.h>
 
 namespace blink {
 
 // WebCoreStringResource is a helper class for v8ExternalString. It is used
 // to manage the life-cycle of the underlying buffer of the external string.
 class WebCoreStringResourceBase {
@@ skipping 14 matching lines @@
         : m_plainString(string.string())
         , m_atomicString(string)
     {
 #if ENABLE(ASSERT)
         m_threadId = WTF::currentThread();
 #endif
         ASSERT(!string.isNull());
         v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(string));
     }
 
+    explicit WebCoreStringResourceBase(const CompressibleString& string)
+        : m_compressibleString(string)
+    {
+#if ENABLE(ASSERT)
+        m_threadId = WTF::currentThread();
+#endif
+        ASSERT(!string.isNull());
+        v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(string));
+    }
+
     virtual ~WebCoreStringResourceBase()
     {
 #if ENABLE(ASSERT)
         ASSERT(m_threadId == WTF::currentThread());
 #endif
-        int reducedExternalMemory = -memoryConsumption(m_plainString);
-        if (m_plainString.impl() != m_atomicString.impl() && !m_atomicString.isNull())
-            reducedExternalMemory -= memoryConsumption(m_atomicString.string());
+        int reducedExternalMemory = 0;
+        if (LIKELY(m_compressibleString.isNull())) {
+            reducedExternalMemory = -memoryConsumption(m_plainString);
+            if (m_plainString.impl() != m_atomicString.impl() && !m_atomicString.isNull())
+                reducedExternalMemory -= memoryConsumption(m_atomicString.string());
+        } else {
+            reducedExternalMemory = -memoryConsumption(m_compressibleString);
+        }
         v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(reducedExternalMemory);
+
+        // FIX this!

[haraken, 2016/01/15 12:46:21]

What do you mean?

[hajimehoshi, 2016/01/18 09:42:26]

Ah, sorry... I mean we need to decide if memoryConsumption expects 'compressed'
string size or 'uncompressed' string size. In the current situation, the strings
are never compressed and we don't have to care.

     }
 
-    const String& webcoreString() { return m_plainString; }
+    String webcoreString()
+    {
+        if (!m_compressibleString.isNull()) {

[haraken, 2016/01/15 12:46:20]

Add UNLIKELY.

[hajimehoshi, 2016/01/18 09:42:26]

Done.

+            ASSERT(m_plainString.isNull());
+            ASSERT(m_atomicString.isNull());
+            return m_compressibleString.toString();
+        }
+        return m_plainString;
+    }
 
-    const AtomicString& atomicString()
+    AtomicString atomicString()
     {
 #if ENABLE(ASSERT)
         ASSERT(m_threadId == WTF::currentThread());
 #endif
+        if (!m_compressibleString.isNull()) {

[haraken, 2016/01/15 12:46:20]

Add UNLIKELY.

[hajimehoshi, 2016/01/18 09:42:26]

Done.

+            ASSERT(m_plainString.isNull());
+            ASSERT(m_atomicString.isNull());
+            return AtomicString(m_compressibleString.toString());
+        }
         if (m_atomicString.isNull()) {
             m_atomicString = AtomicString(m_plainString);
             ASSERT(!m_atomicString.isNull());
             if (m_plainString.impl() != m_atomicString.impl())
                 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(m_atomicString.string()));
         }
         return m_atomicString;
     }
 
+    const CompressibleString& compressibleString() { return m_compressibleString; }
+
 protected:
     // A shallow copy of the string. Keeps the string buffer alive until the V8 engine garbage collects it.
     String m_plainString;
     // If this string is atomic or has been made atomic earlier the
     // atomic string is held here. In the case where the string starts
     // off non-atomic and becomes atomic later it is necessary to keep
     // the original string alive because v8 may keep derived pointers
     // into that string.
     AtomicString m_atomicString;
 
+    CompressibleString m_compressibleString;
+
 private:
     static int memoryConsumption(const String& string)
     {
         return string.length() * (string.is8Bit() ? sizeof(LChar) : sizeof(UChar));
     }
+
+    static int memoryConsumption(const CompressibleString& string)
+    {
+        return string.currentSizeInBytes();
+    }
+
 #if ENABLE(ASSERT)
     WTF::ThreadIdentifier m_threadId;
 #endif
 };
 
 class WebCoreStringResource16 final : public WebCoreStringResourceBase, public v8::String::ExternalStringResource {
     WTF_MAKE_NONCOPYABLE(WebCoreStringResource16);
 public:
     explicit WebCoreStringResource16(const String& string)
         : WebCoreStringResourceBase(string)
@@ skipping 29 matching lines @@
         ASSERT(string.is8Bit());
     }
 
     size_t length() const override { return m_plainString.impl()->length(); }
     const char* data() const override
     {
         return reinterpret_cast<const char*>(m_plainString.impl()->characters8());
     }
 };
 
+class WebCoreCompressibleStringResource16 final : public WebCoreStringResourceBase, public v8::String::ExternalStringResource {
+    WTF_MAKE_NONCOPYABLE(WebCoreCompressibleStringResource16);
+public:
+    explicit WebCoreCompressibleStringResource16(const CompressibleString& string)
+        : WebCoreStringResourceBase(string)
+    {
+        // ASSERT(m_string);

[haraken, 2016/01/15 12:46:21]

Remove this.

[hajimehoshi, 2016/01/18 09:42:26]

Done.

+        ASSERT(!m_compressibleString.is8Bit());
+    }
+
+    bool IsCompressible() const override { return true; }
+
+    size_t length() const override
+    {
+        return m_compressibleString.length();
+    }
+
+    const uint16_t* data() const override
+    {
+        return reinterpret_cast<const uint16_t*>(m_compressibleString.characters16());
+    }
+};
+
+class WebCoreCompressibleStringResource8 final : public WebCoreStringResourceBase, public v8::String::ExternalOneByteStringResource {
+    WTF_MAKE_NONCOPYABLE(WebCoreCompressibleStringResource8);
+public:
+    explicit WebCoreCompressibleStringResource8(const CompressibleString& string)
+        : WebCoreStringResourceBase(string)
+    {
+        ASSERT(m_compressibleString.is8Bit());
+    }
+
+    bool IsCompressible() const override { return true; }
+
+    size_t length() const override
+    {
+        return m_compressibleString.length();
+    }
+
+    const char* data() const override
+    {
+        return reinterpret_cast<const char*>(m_compressibleString.characters8());
+    }
+};
+
 enum ExternalMode {
     Externalize,
     DoNotExternalize
 };
 
 template <typename StringType>
 CORE_EXPORT StringType v8StringToWebCoreString(v8::Local<v8::String>, ExternalMode);
 CORE_EXPORT String int32ToWebCoreString(int value);
 
 // V8StringResource is an adapter class that converts V8 values to Strings
@@ skipping 154 matching lines @@
 }
 
 template<> inline String V8StringResource<TreatNullAndUndefinedAsNullString>::fallbackString() const
 {
     return String();
 }
 
 } // namespace blink
 
 #endif // V8StringResource_h