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 "JSCInlines.h"
  33 #include "Structure.h"
  34
  35 namespace JSC {
  36
  37 WeakBlock* WeakBlock::create(DeadBlock* block)
  38 {
  39     Region* region = block->region();
  40     return new (NotNull, block) WeakBlock(region);
  41 }
  42
  43 WeakBlock::WeakBlock(Region* region)
  44     : HeapBlock<WeakBlock>(region)
  45 {
  46     for (size_t i = 0; i < weakImplCount(); ++i) {
  47         WeakImpl* weakImpl = &weakImpls()[i];
  48         new (NotNull, weakImpl) WeakImpl;
  49         addToFreeList(&m_sweepResult.freeList, weakImpl);
  50     }
  51
  52     ASSERT(isEmpty());
  53 }
  54
  55 void WeakBlock::lastChanceToFinalize()
  56 {
  57     for (size_t i = 0; i < weakImplCount(); ++i) {
  58         WeakImpl* weakImpl = &weakImpls()[i];
  59         if (weakImpl->state() >= WeakImpl::Finalized)
  60             continue;
  61         weakImpl->setState(WeakImpl::Dead);
  62         finalize(weakImpl);
  63     }
  64 }
  65
  66 void WeakBlock::sweep()
  67 {
  68     // If a block is completely empty, a sweep won't have any effect.
  69     if (isEmpty())
  70         return;
  71
  72     SweepResult sweepResult;
  73     for (size_t i = 0; i < weakImplCount(); ++i) {
  74         WeakImpl* weakImpl = &weakImpls()[i];
  75         if (weakImpl->state() == WeakImpl::Dead)
  76             finalize(weakImpl);
  77         if (weakImpl->state() == WeakImpl::Deallocated)
  78             addToFreeList(&sweepResult.freeList, weakImpl);
  79         else
  80             sweepResult.blockIsFree = false;
  81     }
  82
  83     m_sweepResult = sweepResult;
  84     ASSERT(!m_sweepResult.isNull());
  85 }
  86
  87 void WeakBlock::visit(HeapRootVisitor& heapRootVisitor)
  88 {
  89     // If a block is completely empty, a visit won't have any effect.
  90     if (isEmpty())
  91         return;
  92
  93     SlotVisitor& visitor = heapRootVisitor.visitor();
  94
  95     for (size_t i = 0; i < weakImplCount(); ++i) {
  96         WeakImpl* weakImpl = &weakImpls()[i];
  97         if (weakImpl->state() != WeakImpl::Live)
  98             continue;
  99
 100         const JSValue& jsValue = weakImpl->jsValue();
 101         if (Heap::isLive(jsValue.asCell()))
 102             continue;
 103
 104         WeakHandleOwner* weakHandleOwner = weakImpl->weakHandleOwner();
 105         if (!weakHandleOwner)
 106             continue;
 107
 108         if (!weakHandleOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(&const_cast<JSValue&>(jsValue)), weakImpl->context(), visitor))
 109             continue;
 110
 111         heapRootVisitor.visit(&const_cast<JSValue&>(jsValue));
 112     }
 113 }
 114
 115 void WeakBlock::reap()
 116 {
 117     // If a block is completely empty, a reaping won't have any effect.
 118     if (isEmpty())
 119         return;
 120
 121     for (size_t i = 0; i < weakImplCount(); ++i) {
 122         WeakImpl* weakImpl = &weakImpls()[i];
 123         if (weakImpl->state() > WeakImpl::Dead)
 124             continue;
 125
 126         if (Heap::isLive(weakImpl->jsValue().asCell())) {
 127             ASSERT(weakImpl->state() == WeakImpl::Live);
 128             continue;
 129         }
 130
 131         weakImpl->setState(WeakImpl::Dead);
 132     }
 133 }
 134
 135 } // namespace JSC