Experimental CompressibleString UMA

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

Index: third_party/WebKit/Source/bindings/core/v8/V8StringResource.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8StringResource.h b/third_party/WebKit/Source/bindings/core/v8/V8StringResource.h
index 83316f8f6e49a5432c9895c4287c5c0264872e83..5fb049c2e76802d236970a931a2bcb690a47215c 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8StringResource.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8StringResource.h
@@ -28,6 +28,7 @@
 
 #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"
@@ -62,24 +63,54 @@ public:
         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());
@@ -89,6 +120,8 @@ public:
         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;
@@ -99,11 +132,19 @@ protected:
     // 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
@@ -153,6 +194,51 @@ public:
     }
 };
 
+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