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      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
    102