heap/WeakBlock.cpp

   1 /*
   2  * Copyright (C) 2012 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. AND ITS CONTRIBUTORS ``AS IS''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "WeakBlock.h"
  28
  29 #include "Heap.h"
  30 #include "HeapRootVisitor.h"
  31 #include "JSObject.h"
  32 #include "ScopeChain.h"
  33 #include "Structure.h"
  34
  35 namespace JSC {
  36
  37 WeakBlock* WeakBlock::create()
  38 {
  39     PageAllocation allocation = PageAllocation::allocate(blockSize, OSAllocator::JSGCHeapPages);
  40     if (!static_cast<bool>(allocation))
  41         CRASH();
  42     return new (NotNull, allocation.base()) WeakBlock(allocation);
  43 }
  44
  45 void WeakBlock::destroy(WeakBlock* block)
  46 {
  47     block->m_allocation.deallocate();
  48 }
  49
  50 WeakBlock::WeakBlock(PageAllocation& allocation)
  51     : m_allocation(allocation)
  52 {
  53     for (size_t i = 0; i < weakImplCount(); ++i) {
  54         WeakImpl* weakImpl = &weakImpls()[i];
  55         new (NotNull, weakImpl) WeakImpl;
  56         addToFreeList(&m_sweepResult.freeList, weakImpl);
  57     }
  58
  59     ASSERT(!m_sweepResult.isNull() && m_sweepResult.blockIsFree);
  60 }
  61
  62 void WeakBlock::finalizeAll()
  63 {
  64     for (size_t i = 0; i < weakImplCount(); ++i) {
  65         WeakImpl* weakImpl = &weakImpls()[i];
  66         if (weakImpl->state() >= WeakImpl::Finalized)
  67             continue;
  68         weakImpl->setState(WeakImpl::Dead);
  69         finalize(weakImpl);
  70     }
  71 }
  72
  73 void WeakBlock::sweep()
  74 {
  75     if (!m_sweepResult.isNull())
  76         return;
  77
  78     SweepResult sweepResult;
  79     for (size_t i = 0; i < weakImplCount(); ++i) {
  80         WeakImpl* weakImpl = &weakImpls()[i];
  81         if (weakImpl->state() == WeakImpl::Dead)
  82             finalize(weakImpl);
  83         if (weakImpl->state() == WeakImpl::Deallocated)
  84             addToFreeList(&sweepResult.freeList, weakImpl);
  85         else
  86             sweepResult.blockIsFree = false;
  87     }
  88
  89     m_sweepResult = sweepResult;
  90     ASSERT(!m_sweepResult.isNull());
  91 }
  92
  93 void WeakBlock::visitLiveWeakImpls(HeapRootVisitor& heapRootVisitor)
  94 {
  95     // If a block is completely empty, a visit won't have any effect.
  96     if (!m_sweepResult.isNull() && m_sweepResult.blockIsFree)
  97         return;
  98
  99     SlotVisitor& visitor = heapRootVisitor.visitor();
 100
 101     for (size_t i = 0; i < weakImplCount(); ++i) {
 102         WeakImpl* weakImpl = &weakImpls()[i];
 103         if (weakImpl->state() != WeakImpl::Live)
 104             continue;
 105
 106         const JSValue& jsValue = weakImpl->jsValue();
 107         if (Heap::isMarked(jsValue.asCell()))
 108             continue;
 109
 110         WeakHandleOwner* weakHandleOwner = weakImpl->weakHandleOwner();
 111         if (!weakHandleOwner)
 112             continue;
 113
 114         if (!weakHandleOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(&const_cast<JSValue&>(jsValue)), weakImpl->context(), visitor))
 115             continue;
 116
 117         heapRootVisitor.visit(&const_cast<JSValue&>(jsValue));
 118     }
 119 }
 120
 121 void WeakBlock::visitDeadWeakImpls(HeapRootVisitor&)
 122 {
 123     // If a block is completely empty, a visit won't have any effect.
 124     if (!m_sweepResult.isNull() && m_sweepResult.blockIsFree)
 125         return;
 126
 127     for (size_t i = 0; i < weakImplCount(); ++i) {
 128         WeakImpl* weakImpl = &weakImpls()[i];
 129         if (weakImpl->state() > WeakImpl::Dead)
 130             continue;
 131
 132         if (Heap::isMarked(weakImpl->jsValue().asCell())) {
 133             ASSERT(weakImpl->state() == WeakImpl::Live);
 134             continue;
 135         }
 136
 137         weakImpl->setState(WeakImpl::Dead);
 138     }
 139 }
 140
 141 } // namespace JSC