runtime/DateInstanceCache.h

   1 /*
   2  * Copyright (C) 2009 Apple Inc. All Rights Reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef DateInstanceCache_h
  27 #define DateInstanceCache_h
  28
  29 #include "JSDateMath.h"
  30 #include <wtf/FixedArray.h>
  31 #include <wtf/HashFunctions.h>
  32 #include <wtf/PassRefPtr.h>
  33 #include <wtf/RefCounted.h>
  34
  35 namespace JSC {
  36
  37     class DateInstanceData : public RefCounted<DateInstanceData> {
  38     public:
  39         static PassRefPtr<DateInstanceData> create() { return adoptRef(new DateInstanceData); }
  40
  41         double m_gregorianDateTimeCachedForMS;
  42         GregorianDateTime m_cachedGregorianDateTime;
  43         double m_gregorianDateTimeUTCCachedForMS;
  44         GregorianDateTime m_cachedGregorianDateTimeUTC;
  45
  46     private:
  47         DateInstanceData()
  48             : m_gregorianDateTimeCachedForMS(QNaN)
  49             , m_gregorianDateTimeUTCCachedForMS(QNaN)
  50         {
  51         }
  52     };
  53
  54     class DateInstanceCache {
  55     public:
  56         DateInstanceCache()
  57         {
  58             reset();
  59         }
  60
  61         void reset()
  62         {
  63             for (size_t i = 0; i < cacheSize; ++i)
  64                 m_cache[i].key = QNaN;
  65         }
  66
  67         DateInstanceData* add(double d)
  68         {
  69             CacheEntry& entry = lookup(d);
  70             if (d == entry.key)
  71                 return entry.value.get();
  72
  73             entry.key = d;
  74             entry.value = DateInstanceData::create();
  75             return entry.value.get();
  76         }
  77
  78     private:
  79         static const size_t cacheSize = 16;
  80
  81         struct CacheEntry {
  82             double key;
  83             RefPtr<DateInstanceData> value;
  84         };
  85
  86         CacheEntry& lookup(double d) { return m_cache[WTF::FloatHash<double>::hash(d) & (cacheSize - 1)]; }
  87
  88         FixedArray<CacheEntry, cacheSize> m_cache;
  89     };
  90
  91 } // namespace JSC
  92
  93 #endif // DateInstanceCache_h