Revert 157524 "Get rid of fastMallocGoodSize() and replace it wi..."

trunk/Source/wtf/QuantizedAllocation.h

-/*
- * Copyright (C) 2013 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:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN 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 WTF_QuantizedAllocation_h
-#define WTF_QuantizedAllocation_h
-
-// DESCRIPTION
-// QuantizedAllocation::quantizedSize() rounds up the specific size such that:
-// 1) Granularity of allocation sizes is >1, and grows as a fraction of the
-// allocation size. This property can be used to limit bucket fragmentation
-// when sitting on top of a high-granularity allocator such as PartitionAlloc.
-// 2) The sizes are likely (but not guaranteed) to correspond to exact "bucket
-// sizes" of any underlying allocator that implements standard bucketing.
-// This currently includes tcmalloc, Windows LFH and PartitionAlloc.
-
-#include <limits.h>
-
-namespace WTF {
-
-class QuantizedAllocation {
-public:
-    // Allocations above 32k are rounded to 4k (which is typically the system
-    // page size).
-    static const size_t kMaxAllocation = 32768;
-    static const size_t kMaxRounding = 4096;
-
-    // This is the minimum granularity of allocation, currently 16 bytes.
-    static const size_t kMinRounding = 16;
-
-    // After 256 bytes, the granularity doubles, and proceeds to double again
-    // as the allocation size further doubles.
-    static const size_t kMinRoundingLimit = 256;
-    static const size_t kTableSize = kMaxAllocation / kMinRoundingLimit;
-
-    // Using "unsigned" is not a limitation because Chromium's max malloc() is
-    // 2GB even on 64-bit.
-    static const size_t kMaxUnquantizedAllocation = UINT_MAX - kMaxRounding;
-
-    static void init();
-
-    static size_t quantizedSize(size_t size)
-    {
-        size_t roundToLessOne;
-        if (UNLIKELY(size >= kMaxAllocation))
-            roundToLessOne = kMaxRounding - 1;
-        else
-            roundToLessOne = table[size / kMinRoundingLimit];
-        return (size + roundToLessOne) & ~roundToLessOne;
-    }
-
-private:
-    static unsigned short table[kTableSize];
-};
-
-} // namespace WTF
-
-#endif // WTF_QuantizedAllocation_h