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
35namespace JSC {
36
37WeakBlock* WeakBlock::create(DeadBlock* block)
38{
39    Region* region = block->region();
40    return new (NotNull, block) WeakBlock(region);
41}
42
43WeakBlock::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
55void 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
66void 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
87void 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
115void 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
136