1 /*
2 * Copyright (C) 2011 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 "HandleHeap.h"
28
29 #include "JSObject.h"
30
31 namespace JSC {
32
~WeakHandleOwner()33 WeakHandleOwner::~WeakHandleOwner()
34 {
35 }
36
isReachableFromOpaqueRoots(Handle<Unknown>,void *,MarkStack &)37 bool WeakHandleOwner::isReachableFromOpaqueRoots(Handle<Unknown>, void*, MarkStack&)
38 {
39 return false;
40 }
41
finalize(Handle<Unknown>,void *)42 void WeakHandleOwner::finalize(Handle<Unknown>, void*)
43 {
44 }
45
HandleHeap(JSGlobalData * globalData)46 HandleHeap::HandleHeap(JSGlobalData* globalData)
47 : m_globalData(globalData)
48 , m_nextToFinalize(0)
49 {
50 grow();
51 }
52
grow()53 void HandleHeap::grow()
54 {
55 Node* block = m_blockStack.grow();
56 for (int i = m_blockStack.blockLength - 1; i >= 0; --i) {
57 Node* node = &block[i];
58 new (node) Node(this);
59 m_freeList.push(node);
60 }
61 }
62
markStrongHandles(HeapRootMarker & heapRootMarker)63 void HandleHeap::markStrongHandles(HeapRootMarker& heapRootMarker)
64 {
65 Node* end = m_strongList.end();
66 for (Node* node = m_strongList.begin(); node != end; node = node->next())
67 heapRootMarker.mark(node->slot());
68 }
69
markWeakHandles(HeapRootMarker & heapRootMarker)70 void HandleHeap::markWeakHandles(HeapRootMarker& heapRootMarker)
71 {
72 MarkStack& markStack = heapRootMarker.markStack();
73
74 Node* end = m_weakList.end();
75 for (Node* node = m_weakList.begin(); node != end; node = node->next()) {
76 ASSERT(isValidWeakNode(node));
77 JSCell* cell = node->slot()->asCell();
78 if (Heap::isMarked(cell))
79 continue;
80
81 WeakHandleOwner* weakOwner = node->weakOwner();
82 if (!weakOwner)
83 continue;
84
85 if (!weakOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(node->slot()), node->weakOwnerContext(), markStack))
86 continue;
87
88 heapRootMarker.mark(node->slot());
89 }
90 }
91
finalizeWeakHandles()92 void HandleHeap::finalizeWeakHandles()
93 {
94 Node* end = m_weakList.end();
95 for (Node* node = m_weakList.begin(); node != end; node = m_nextToFinalize) {
96 m_nextToFinalize = node->next();
97
98 ASSERT(isValidWeakNode(node));
99 JSCell* cell = node->slot()->asCell();
100 if (Heap::isMarked(cell))
101 continue;
102
103 if (WeakHandleOwner* weakOwner = node->weakOwner()) {
104 weakOwner->finalize(Handle<Unknown>::wrapSlot(node->slot()), node->weakOwnerContext());
105 if (m_nextToFinalize != node->next()) // Owner deallocated node.
106 continue;
107 }
108
109 *node->slot() = JSValue();
110 SentinelLinkedList<Node>::remove(node);
111 m_immediateList.push(node);
112 }
113
114 m_nextToFinalize = 0;
115 }
116
writeBarrier(HandleSlot slot,const JSValue & value)117 void HandleHeap::writeBarrier(HandleSlot slot, const JSValue& value)
118 {
119 ASSERT(!m_nextToFinalize); // Forbid assignment to handles during the finalization phase, since it would violate many GC invariants.
120
121 if (!value == !*slot && slot->isCell() == value.isCell())
122 return;
123
124 Node* node = toNode(slot);
125 SentinelLinkedList<Node>::remove(node);
126 if (!value || !value.isCell()) {
127 m_immediateList.push(node);
128 return;
129 }
130
131 if (node->isWeak()) {
132 m_weakList.push(node);
133 return;
134 }
135
136 m_strongList.push(node);
137 }
138
protectedGlobalObjectCount()139 unsigned HandleHeap::protectedGlobalObjectCount()
140 {
141 unsigned count = 0;
142 Node* end = m_strongList.end();
143 for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
144 JSValue value = *node->slot();
145 if (value.isObject() && asObject(value.asCell())->isGlobalObject())
146 count++;
147 }
148 return count;
149 }
150
151 #if !ASSERT_DISABLED
isValidWeakNode(Node * node)152 bool HandleHeap::isValidWeakNode(Node* node)
153 {
154 if (!node->isWeak())
155 return false;
156
157 JSValue value = *node->slot();
158 if (!value || !value.isCell())
159 return false;
160
161 JSCell* cell = value.asCell();
162 if (!cell || !cell->structure())
163 return false;
164
165 #if ENABLE(JSC_ZOMBIES)
166 if (cell->isZombie())
167 return false;
168 #endif
169
170 return true;
171 }
172 #endif
173
174 } // namespace JSC
175