runtime/WeakMapData.cpp

   1 /*
   2  * Copyright (C) 2013 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 "WeakMapData.h"
  28
  29 #include "CopiedAllocator.h"
  30 #include "CopyVisitorInlines.h"
  31 #include "ExceptionHelpers.h"
  32 #include "JSCJSValueInlines.h"
  33 #include "SlotVisitorInlines.h"
  34
  35 #include <wtf/MathExtras.h>
  36
  37 namespace JSC {
  38
  39 const ClassInfo WeakMapData::s_info = { "WeakMapData", 0, 0, 0, CREATE_METHOD_TABLE(WeakMapData) };
  40
  41 WeakMapData::WeakMapData(VM& vm)
  42     : Base(vm, vm.weakMapDataStructure.get())
  43     , m_deadKeyCleaner(this)
  44 {
  45 }
  46
  47 void WeakMapData::finishCreation(VM& vm)
  48 {
  49     Base::finishCreation(vm);
  50 }
  51
  52 void WeakMapData::destroy(JSCell* cell)
  53 {
  54     static_cast<WeakMapData*>(cell)->~WeakMapData();
  55 }
  56
  57 void WeakMapData::visitChildren(JSCell* cell, SlotVisitor& visitor)
  58 {
  59     Base::visitChildren(cell, visitor);
  60     WeakMapData* thisObj = jsCast<WeakMapData*>(cell);
  61     visitor.addUnconditionalFinalizer(&thisObj->m_deadKeyCleaner);
  62     visitor.addWeakReferenceHarvester(&thisObj->m_deadKeyCleaner);
  63
  64     // Rough approximation of the external storage needed for the hashtable.
  65     // This isn't exact, but it is close enough, and proportional to the actual
  66     // external mermory usage.
  67     visitor.reportExtraMemoryUsage(thisObj, thisObj->m_map.capacity() * (sizeof(JSObject*) + sizeof(WriteBarrier<Unknown>)));
  68 }
  69
  70 void WeakMapData::set(VM& vm, JSObject* key, JSValue value)
  71 {
  72     // Here we force the write barrier on the key.
  73     auto result = m_map.add(WriteBarrier<JSObject>(vm, this, key).get(), WriteBarrier<Unknown>());
  74     result.iterator->value.set(vm, this, value);
  75 }
  76
  77 JSValue WeakMapData::get(JSObject* key)
  78 {
  79     auto iter = m_map.find(key);
  80     if (iter == m_map.end())
  81         return jsUndefined();
  82     return iter->value.get();
  83 }
  84
  85 bool WeakMapData::remove(JSObject* key)
  86 {
  87     auto iter = m_map.find(key);
  88     if (iter == m_map.end())
  89         return false;
  90
  91     m_map.remove(iter);
  92     return true;
  93 }
  94
  95 bool WeakMapData::contains(JSObject* key)
  96 {
  97     return m_map.contains(key);
  98 }
  99
 100 void WeakMapData::clear()
 101 {
 102     m_map.clear();
 103 }
 104
 105 void WeakMapData::DeadKeyCleaner::visitWeakReferences(SlotVisitor& visitor)
 106 {
 107     m_liveKeyCount = 0;
 108     for (auto it = m_target->m_map.begin(), end = m_target->m_map.end(); it != end; ++it) {
 109         if (!Heap::isMarked(it->key))
 110             continue;
 111         m_liveKeyCount++;
 112         visitor.append(&it->value);
 113     }
 114     RELEASE_ASSERT(m_liveKeyCount <= m_target->m_map.size());
 115 }
 116
 117 void WeakMapData::DeadKeyCleaner::finalizeUnconditionally()
 118 {
 119     if (m_liveKeyCount > m_target->m_map.size() / 2) {
 120         RELEASE_ASSERT(m_liveKeyCount <= m_target->m_map.size());
 121         int deadCount = m_target->m_map.size() - m_liveKeyCount;
 122         if (!deadCount)
 123             return;
 124         Vector<JSObject*> deadEntries;
 125         deadEntries.reserveCapacity(deadCount);
 126         for (auto it = m_target->m_map.begin(), end = m_target->m_map.end(); it != end; ++it) {
 127             if (Heap::isMarked(it->key))
 128                 continue;
 129             deadEntries.uncheckedAppend(it->key);
 130         }
 131         for (size_t i = 0; i < deadEntries.size(); i++)
 132             m_target->m_map.remove(deadEntries[i]);
 133     } else {
 134         MapType newMap;
 135         for (auto it = m_target->m_map.begin(), end = m_target->m_map.end(); it != end; ++it) {
 136             if (!Heap::isMarked(it->key))
 137                 continue;
 138             newMap.add(it->key, it->value);
 139         }
 140         m_target->m_map.swap(newMap);
 141     }
 142 }
 143
 144 }