Experimental CompressibleString UMA

third_party/WebKit/Source/platform/text/CompressibleString.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CompressibleString_h
+#define CompressibleString_h
+
+#include "platform/PlatformExport.h"
+#include "wtf/HashTableDeletedValueType.h"

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

This wouldn't be needed.

[hajimehoshi, 2016/01/18 09:42:27]

Done.

+#include "wtf/text/Unicode.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+// TODO(hajimehoshi): Now these classes are in platform/text to use UMA. Move
+// them to wtf/text.
+
+class PLATFORM_EXPORT CompressibleStringImpl : public RefCounted<CompressibleStringImpl> {

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

Add final.

[hajimehoshi, 2016/01/18 09:42:27]

Done.

+    WTF_MAKE_NONCOPYABLE(CompressibleStringImpl);
+public:
+    static void compressAll();
+    static void setPageBackground(bool);
+
+    CompressibleStringImpl(PassRefPtr<StringImpl>);
+    ~CompressibleStringImpl();
+
+    bool isEmpty() const { return originalLength() == 0; }
+
+    PassRefPtr<StringImpl> impl() { return m_impl; }

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

Add const.

[hajimehoshi, 2016/01/18 09:42:27]

This was removed.

+    bool isCompressed() const { return m_isCompressed; }

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

Add const.

[hajimehoshi, 2016/01/18 09:42:27]

Where do I have to add const?

+    unsigned originalLength() const { return m_impl->length(); }
+    bool is8Bit() const { return m_impl->is8Bit(); }
+
+    unsigned originalContentSizeInBytes() const;

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

originalContentSizeInBytes => originalSizeInBytes (for consistency with
currentSizeInBytes)?

[hajimehoshi, 2016/01/18 09:42:27]

StringImpl's sizeInBytes contains the size of StringImpl itself while String's
sizeInBytes only contains the content size. This is inconsistent if anything and
I chose to clarify the new name.

+    unsigned currentSizeInBytes() const;
+
+    String toString();
+    const LChar* characters8();
+    const UChar* characters16();
+
+    void compressString();
+    void decompressString();
+
+private:
+    static bool s_isPageBackground;
+
+    RefPtr<StringImpl> m_impl;
+    bool m_isCompressed;
+};
+
+class PLATFORM_EXPORT CompressibleString {

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

Add final.

[hajimehoshi, 2016/01/18 09:42:27]

Done.

+public:
+    CompressibleString();
+    CompressibleString(const CompressibleString&);
+    explicit CompressibleString(PassRefPtr<StringImpl>);
+
+    bool isNull() const { return !m_impl; }
+    bool isEmpty() const { return isNull() || m_impl->isEmpty(); }
+    unsigned length() const { return m_impl ? m_impl->originalLength() : 0; }
+
+    unsigned currentSizeInBytes() const { return m_impl ? m_impl->currentSizeInBytes() : 0; }
+
+    bool isCompressed() const { return m_impl ? m_impl->isCompressed() : false; }
+    bool is8Bit() const { return m_impl->is8Bit(); }

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

m_impl ? m_impl->is8Bit() : false;

[hajimehoshi, 2016/01/18 09:42:27]

Done.

+
+    String toString() const { return m_impl ? m_impl->toString() : String(); }
+    const LChar* characters8() const { return m_impl ? m_impl->characters8() : nullptr; }
+    const UChar* characters16() const { return m_impl ? m_impl->characters16() : nullptr; }
+
+    PassRefPtr<CompressibleStringImpl> impl() const { return m_impl; }
+
+private:
+    void compressString() const;
+    void decompressString() const;
+
+    mutable RefPtr<CompressibleStringImpl> m_impl;
+};
+
+} // namespace blink
+
+using blink::CompressibleString;
+using blink::CompressibleStringImpl;
+
+#endif