1/*
2 * Copyright (C) 2012-2017 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 "CellContainerInlines.h"
30#include "Heap.h"
31#include "HeapSnapshotBuilder.h"
32#include "JSCInlines.h"
33#include "JSObject.h"
34#include "WeakHandleOwner.h"
35
36namespace JSC {
37
38WeakBlock* WeakBlock::create(Heap& heap, CellContainer container)
39{
40 heap.didAllocateBlock(WeakBlock::blockSize);
41 return new (NotNull, fastMalloc(blockSize)) WeakBlock(container);
42}
43
44void WeakBlock::destroy(Heap& heap, WeakBlock* block)
45{
46 block->~WeakBlock();
47 fastFree(block);
48 heap.didFreeBlock(WeakBlock::blockSize);
49}
50
51WeakBlock::WeakBlock(CellContainer container)
52 : DoublyLinkedListNode<WeakBlock>()
53 , m_container(container)
54{
55 for (size_t i = 0; i < weakImplCount(); ++i) {
56 WeakImpl* weakImpl = &weakImpls()[i];
57 new (NotNull, weakImpl) WeakImpl;
58 addToFreeList(&m_sweepResult.freeList, weakImpl);
59 }
60
61 ASSERT(isEmpty());
62}
63
64void WeakBlock::lastChanceToFinalize()
65{
66 for (size_t i = 0; i < weakImplCount(); ++i) {
67 WeakImpl* weakImpl = &weakImpls()[i];
68 if (weakImpl->state() >= WeakImpl::Finalized)
69 continue;
70 weakImpl->setState(WeakImpl::Dead);
71 finalize(weakImpl);
72 }
73}
74
75void WeakBlock::sweep()
76{
77 // If a block is completely empty, a sweep won't have any effect.
78 if (isEmpty())
79 return;
80
81 SweepResult sweepResult;
82 for (size_t i = 0; i < weakImplCount(); ++i) {
83 WeakImpl* weakImpl = &weakImpls()[i];
84 if (weakImpl->state() == WeakImpl::Dead)
85 finalize(weakImpl);
86 if (weakImpl->state() == WeakImpl::Deallocated)
87 addToFreeList(&sweepResult.freeList, weakImpl);
88 else {
89 sweepResult.blockIsFree = false;
90 if (weakImpl->state() == WeakImpl::Live)
91 sweepResult.blockIsLogicallyEmpty = false;
92 }
93 }
94
95 m_sweepResult = sweepResult;
96 ASSERT(!m_sweepResult.isNull());
97}
98
99template<typename ContainerType>
100void WeakBlock::specializedVisit(ContainerType& container, SlotVisitor& visitor)
101{
102 HeapVersion markingVersion = visitor.markingVersion();
103
104 size_t count = weakImplCount();
105 for (size_t i = 0; i < count; ++i) {
106 WeakImpl* weakImpl = &weakImpls()[i];
107 if (weakImpl->state() != WeakImpl::Live)
108 continue;
109
110 WeakHandleOwner* weakHandleOwner = weakImpl->weakHandleOwner();
111 if (!weakHandleOwner)
112 continue;
113
114 JSValue jsValue = weakImpl->jsValue();
115 if (container.isMarked(markingVersion, jsValue.asCell()))
116 continue;
117
118 const char* reason = "";
119 const char** reasonPtr = nullptr;
120 if (UNLIKELY(visitor.isBuildingHeapSnapshot()))
121 reasonPtr = &reason;
122
123 if (!weakHandleOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(&const_cast<JSValue&>(jsValue)), weakImpl->context(), visitor, reasonPtr))
124 continue;
125
126 visitor.appendUnbarriered(jsValue);
127
128 if (UNLIKELY(visitor.isBuildingHeapSnapshot())) {
129 if (jsValue.isCell())
130 visitor.heapSnapshotBuilder()->setOpaqueRootReachabilityReasonForCell(jsValue.asCell(), *reasonPtr);
131 }
132 }
133}
134
135void WeakBlock::visit(SlotVisitor& visitor)
136{
137 // If a block is completely empty, a visit won't have any effect.
138 if (isEmpty())
139 return;
140
141 // If this WeakBlock doesn't belong to a CellContainer, we won't even be here.
142 ASSERT(m_container);
143
144 if (m_container.isLargeAllocation())
145 specializedVisit(m_container.largeAllocation(), visitor);
146 else
147 specializedVisit(m_container.markedBlock(), visitor);
148}
149
150void WeakBlock::reap()
151{
152 // If a block is completely empty, a reaping won't have any effect.
153 if (isEmpty())
154 return;
155
156 // If this WeakBlock doesn't belong to a CellContainer, we won't even be here.
157 ASSERT(m_container);
158
159 HeapVersion markingVersion = m_container.heap()->objectSpace().markingVersion();
160
161 for (size_t i = 0; i < weakImplCount(); ++i) {
162 WeakImpl* weakImpl = &weakImpls()[i];
163 if (weakImpl->state() > WeakImpl::Dead)
164 continue;
165
166 if (m_container.isMarked(markingVersion, weakImpl->jsValue().asCell())) {
167 ASSERT(weakImpl->state() == WeakImpl::Live);
168 continue;
169 }
170
171 weakImpl->setState(WeakImpl::Dead);
172 }
173}
174
175} // namespace JSC
176