heap/ConservativeRoots.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 ConservativeRoots_h
  27 #define ConservativeRoots_h
  28
  29 #include "Heap.h"
  30 #include <wtf/OSAllocator.h>
  31 #include <wtf/Vector.h>
  32
  33 namespace JSC {
  34
  35 class JSCell;
  36 class Heap;
  37
  38 // May contain duplicates.
  39
  40 class ConservativeRoots {
  41 public:
  42     ConservativeRoots(Heap*);
  43     ~ConservativeRoots();
  44
  45     void add(void*);
  46     void add(void* begin, void* end);
  47
  48     size_t size();
  49     JSCell** roots();
  50
  51 private:
  52     static const size_t inlineCapacity = 128;
  53     static const size_t nonInlineCapacity = 8192 / sizeof(JSCell*);
  54
  55     void grow();
  56
  57     Heap* m_heap;
  58     JSCell** m_roots;
  59     size_t m_size;
  60     size_t m_capacity;
  61     JSCell* m_inlineRoots[inlineCapacity];
  62 };
  63
  64 inline ConservativeRoots::ConservativeRoots(Heap* heap)
  65     : m_heap(heap)
  66     , m_roots(m_inlineRoots)
  67     , m_size(0)
  68     , m_capacity(inlineCapacity)
  69 {
  70 }
  71
  72 inline ConservativeRoots::~ConservativeRoots()
  73 {
  74     if (m_roots != m_inlineRoots)
  75         OSAllocator::decommitAndRelease(m_roots, m_capacity * sizeof(JSCell*));
  76 }
  77
  78 inline void ConservativeRoots::add(void* p)
  79 {
  80     if (!m_heap->contains(p))
  81         return;
  82
  83     if (m_size == m_capacity)
  84         grow();
  85
  86     m_roots[m_size++] = reinterpret_cast<JSCell*>(p);
  87 }
  88
  89 inline size_t ConservativeRoots::size()
  90 {
  91     return m_size;
  92 }
  93
  94 inline JSCell** ConservativeRoots::roots()
  95 {
  96     return m_roots;
  97 }
  98
  99 } // namespace JSC
 100
 101 #endif // ConservativeRoots_h