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/*
* Copyright (C) 2009 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "V8GCController.h"
#include "DOMDataStore.h"
#include "DOMObjectsInclude.h"
#include "V8DOMMap.h"
#include "V8Index.h"
#include "V8Proxy.h"
#include <algorithm>
#include <utility>
#include <v8.h>
#include <v8-debug.h>
#include <wtf/HashMap.h>
#include <wtf/StdLibExtras.h>
#include <wtf/UnusedParam.h>
namespace WebCore {
#ifndef NDEBUG
// Keeps track of global handles created (not JS wrappers
// of DOM objects). Often these global handles are source
// of leaks.
//
// If you want to let a C++ object hold a persistent handle
// to a JS object, you should register the handle here to
// keep track of leaks.
//
// When creating a persistent handle, call:
//
// #ifndef NDEBUG
// V8GCController::registerGlobalHandle(type, host, handle);
// #endif
//
// When releasing the handle, call:
//
// #ifndef NDEBUG
// V8GCController::unregisterGlobalHandle(type, host, handle);
// #endif
//
typedef HashMap<v8::Value*, GlobalHandleInfo*> GlobalHandleMap;
static GlobalHandleMap& globalHandleMap()
{
DEFINE_STATIC_LOCAL(GlobalHandleMap, staticGlobalHandleMap, ());
return staticGlobalHandleMap;
}
// The function is the place to set the break point to inspect
// live global handles. Leaks are often come from leaked global handles.
static void enumerateGlobalHandles()
{
for (GlobalHandleMap::iterator it = globalHandleMap().begin(), end = globalHandleMap().end(); it != end; ++it) {
GlobalHandleInfo* info = it->second;
UNUSED_PARAM(info);
v8::Value* handle = it->first;
UNUSED_PARAM(handle);
}
}
void V8GCController::registerGlobalHandle(GlobalHandleType type, void* host, v8::Persistent<v8::Value> handle)
{
ASSERT(!globalHandleMap().contains(*handle));
globalHandleMap().set(*handle, new GlobalHandleInfo(host, type));
}
void V8GCController::unregisterGlobalHandle(void* host, v8::Persistent<v8::Value> handle)
{
ASSERT(globalHandleMap().contains(*handle));
GlobalHandleInfo* info = globalHandleMap().take(*handle);
ASSERT(info->m_host == host);
delete info;
}
#endif // ifndef NDEBUG
typedef HashMap<Node*, v8::Object*> DOMNodeMap;
typedef HashMap<void*, v8::Object*> DOMObjectMap;
#ifndef NDEBUG
static void enumerateDOMObjectMap(DOMObjectMap& wrapperMap)
{
for (DOMObjectMap::iterator it = wrapperMap.begin(), end = wrapperMap.end(); it != end; ++it) {
v8::Persistent<v8::Object> wrapper(it->second);
V8ClassIndex::V8WrapperType type = V8DOMWrapper::domWrapperType(wrapper);
void* object = it->first;
UNUSED_PARAM(type);
UNUSED_PARAM(object);
}
}
class DOMObjectVisitor : public DOMWrapperMap<void>::Visitor {
public:
void visitDOMWrapper(void* object, v8::Persistent<v8::Object> wrapper)
{
V8ClassIndex::V8WrapperType type = V8DOMWrapper::domWrapperType(wrapper);
UNUSED_PARAM(type);
UNUSED_PARAM(object);
}
};
class EnsureWeakDOMNodeVisitor : public DOMWrapperMap<Node>::Visitor {
public:
void visitDOMWrapper(Node* object, v8::Persistent<v8::Object> wrapper)
{
UNUSED_PARAM(object);
ASSERT(wrapper.IsWeak());
}
};
#endif // NDEBUG
// A map from a DOM node to its JS wrapper, the wrapper
// is kept as a strong reference to survive GCs.
static DOMObjectMap& gcProtectedMap()
{
DEFINE_STATIC_LOCAL(DOMObjectMap, staticGcProtectedMap, ());
return staticGcProtectedMap;
}
void V8GCController::gcProtect(void* domObject)
{
if (!domObject)
return;
if (gcProtectedMap().contains(domObject))
return;
if (!getDOMObjectMap().contains(domObject))
return;
// Create a new (strong) persistent handle for the object.
v8::Persistent<v8::Object> wrapper = getDOMObjectMap().get(domObject);
if (wrapper.IsEmpty())
return;
gcProtectedMap().set(domObject, *v8::Persistent<v8::Object>::New(wrapper));
}
void V8GCController::gcUnprotect(void* domObject)
{
if (!domObject)
return;
if (!gcProtectedMap().contains(domObject))
return;
// Dispose the strong reference.
v8::Persistent<v8::Object> wrapper(gcProtectedMap().take(domObject));
wrapper.Dispose();
}
class GCPrologueVisitor : public DOMWrapperMap<void>::Visitor {
public:
void visitDOMWrapper(void* object, v8::Persistent<v8::Object> wrapper)
{
ASSERT(wrapper.IsWeak());
V8ClassIndex::V8WrapperType type = V8DOMWrapper::domWrapperType(wrapper);
switch (type) {
#define MAKE_CASE(TYPE, NAME) \
case V8ClassIndex::TYPE: { \
NAME* impl = static_cast<NAME*>(object); \
if (impl->hasPendingActivity()) \
wrapper.ClearWeak(); \
break; \
}
ACTIVE_DOM_OBJECT_TYPES(MAKE_CASE)
default:
ASSERT_NOT_REACHED();
#undef MAKE_CASE
}
// Additional handling of message port ensuring that entangled ports also
// have their wrappers entangled. This should ideally be handled when the
// ports are actually entangled in MessagePort::entangle, but to avoid
// forking MessagePort.* this is postponed to GC time. Having this postponed
// has the drawback that the wrappers are "entangled/unentangled" for each
// GC even though their entaglement most likely is still the same.
if (type == V8ClassIndex::MESSAGEPORT) {
// Mark each port as in-use if it's entangled. For simplicity's sake, we assume all ports are remotely entangled,
// since the Chromium port implementation can't tell the difference.
MessagePort* port1 = static_cast<MessagePort*>(object);
if (port1->isEntangled())
wrapper.ClearWeak();
}
}
};
class GrouperItem {
public:
GrouperItem(uintptr_t groupId, Node* node, v8::Persistent<v8::Object> wrapper)
: m_groupId(groupId)
, m_node(node)
, m_wrapper(wrapper)
{
}
uintptr_t groupId() const { return m_groupId; }
Node* node() const { return m_node; }
v8::Persistent<v8::Object> wrapper() const { return m_wrapper; }
private:
uintptr_t m_groupId;
Node* m_node;
v8::Persistent<v8::Object> m_wrapper;
};
bool operator<(const GrouperItem& a, const GrouperItem& b)
{
return a.groupId() < b.groupId();
}
typedef Vector<GrouperItem> GrouperList;
#if PLATFORM(ANDROID)
// Android's implementation of std::sort seems unable to do the necessary
// template matching to pick up operator< for GrouperItem, so we have to
// manually pass a comparison function.
static bool compareGrouperItem(const GrouperItem& a, const GrouperItem& b)
{
return a < b;
}
#endif
class ObjectGrouperVisitor : public DOMWrapperMap<Node>::Visitor {
public:
ObjectGrouperVisitor()
{
// FIXME: grouper_.reserveCapacity(node_map.size()); ?
}
void visitDOMWrapper(Node* node, v8::Persistent<v8::Object> wrapper)
{
// If the node is in document, put it in the ownerDocument's object group.
//
// If an image element was created by JavaScript "new Image",
// it is not in a document. However, if the load event has not
// been fired (still onloading), it is treated as in the document.
//
// Otherwise, the node is put in an object group identified by the root
// element of the tree to which it belongs.
uintptr_t groupId;
if (node->inDocument() || (node->hasTagName(HTMLNames::imgTag) && !static_cast<HTMLImageElement*>(node)->haveFiredLoadEvent()))
groupId = reinterpret_cast<uintptr_t>(node->document());
else {
Node* root = node;
if (node->isAttributeNode()) {
root = static_cast<Attr*>(node)->ownerElement();
// If the attribute has no element, no need to put it in the group,
// because it'll always be a group of 1.
if (!root)
return;
} else {
while (root->parent())
root = root->parent();
// If the node is alone in its DOM tree (doesn't have a parent or any
// children) then the group will be filtered out later anyway.
if (root == node && !node->hasChildNodes() && !node->hasAttributes())
return;
}
groupId = reinterpret_cast<uintptr_t>(root);
}
m_grouper.append(GrouperItem(groupId, node, wrapper));
}
void applyGrouping()
{
// Group by sorting by the group id.
#if PLATFORM(ANDROID)
std::sort(m_grouper.begin(), m_grouper.end(), compareGrouperItem);
#else
std::sort(m_grouper.begin(), m_grouper.end());
#endif
// FIXME Should probably work in iterators here, but indexes were easier for my simple mind.
for (size_t i = 0; i < m_grouper.size(); ) {
// Seek to the next key (or the end of the list).
size_t nextKeyIndex = m_grouper.size();
for (size_t j = i; j < m_grouper.size(); ++j) {
if (m_grouper[i].groupId() != m_grouper[j].groupId()) {
nextKeyIndex = j;
break;
}
}
ASSERT(nextKeyIndex > i);
// We only care about a group if it has more than one object. If it only
// has one object, it has nothing else that needs to be kept alive.
if (nextKeyIndex - i <= 1) {
i = nextKeyIndex;
continue;
}
Vector<v8::Persistent<v8::Value> > group;
group.reserveCapacity(nextKeyIndex - i);
for (; i < nextKeyIndex; ++i) {
v8::Persistent<v8::Value> wrapper = m_grouper[i].wrapper();
if (!wrapper.IsEmpty())
group.append(wrapper);
/* FIXME: Re-enabled this code to avoid GCing these wrappers!
Currently this depends on looking up the wrapper
during a GC, but we don't know which isolated world
we're in, so it's unclear which map to look in...
// If the node is styled and there is a wrapper for the inline
// style declaration, we need to keep that style declaration
// wrapper alive as well, so we add it to the object group.
if (node->isStyledElement()) {
StyledElement* element = reinterpret_cast<StyledElement*>(node);
CSSStyleDeclaration* style = element->inlineStyleDecl();
if (style != NULL) {
wrapper = getDOMObjectMap().get(style);
if (!wrapper.IsEmpty())
group.append(wrapper);
}
}
*/
}
if (group.size() > 1)
v8::V8::AddObjectGroup(&group[0], group.size());
ASSERT(i == nextKeyIndex);
}
}
private:
GrouperList m_grouper;
};
// Create object groups for DOM tree nodes.
void V8GCController::gcPrologue()
{
v8::HandleScope scope;
#ifndef NDEBUG
DOMObjectVisitor domObjectVisitor;
visitDOMObjectsInCurrentThread(&domObjectVisitor);
#endif
// Run through all objects with possible pending activity making their
// wrappers non weak if there is pending activity.
GCPrologueVisitor prologueVisitor;
visitActiveDOMObjectsInCurrentThread(&prologueVisitor);
// Create object groups.
ObjectGrouperVisitor objectGrouperVisitor;
visitDOMNodesInCurrentThread(&objectGrouperVisitor);
objectGrouperVisitor.applyGrouping();
}
class GCEpilogueVisitor : public DOMWrapperMap<void>::Visitor {
public:
void visitDOMWrapper(void* object, v8::Persistent<v8::Object> wrapper)
{
V8ClassIndex::V8WrapperType type = V8DOMWrapper::domWrapperType(wrapper);
switch (type) {
#define MAKE_CASE(TYPE, NAME) \
case V8ClassIndex::TYPE: { \
NAME* impl = static_cast<NAME*>(object); \
if (impl->hasPendingActivity()) { \
ASSERT(!wrapper.IsWeak()); \
wrapper.MakeWeak(impl, &DOMDataStore::weakActiveDOMObjectCallback); \
} \
break; \
}
ACTIVE_DOM_OBJECT_TYPES(MAKE_CASE)
default:
ASSERT_NOT_REACHED();
#undef MAKE_CASE
}
if (type == V8ClassIndex::MESSAGEPORT) {
MessagePort* port1 = static_cast<MessagePort*>(object);
// We marked this port as reachable in GCPrologueVisitor. Undo this now since the
// port could be not reachable in the future if it gets disentangled (and also
// GCPrologueVisitor expects to see all handles marked as weak).
if (!wrapper.IsWeak() && !wrapper.IsNearDeath())
wrapper.MakeWeak(port1, &DOMDataStore::weakActiveDOMObjectCallback);
}
}
};
int V8GCController::workingSetEstimateMB = 0;
namespace {
int getMemoryUsageInMB()
{
#if PLATFORM(CHROMIUM)
return ChromiumBridge::memoryUsageMB();
#else
return 0;
#endif
}
} // anonymous namespace
void V8GCController::gcEpilogue()
{
v8::HandleScope scope;
// Run through all objects with pending activity making their wrappers weak
// again.
GCEpilogueVisitor epilogueVisitor;
visitActiveDOMObjectsInCurrentThread(&epilogueVisitor);
workingSetEstimateMB = getMemoryUsageInMB();
#ifndef NDEBUG
// Check all survivals are weak.
DOMObjectVisitor domObjectVisitor;
visitDOMObjectsInCurrentThread(&domObjectVisitor);
EnsureWeakDOMNodeVisitor weakDOMNodeVisitor;
visitDOMNodesInCurrentThread(&weakDOMNodeVisitor);
enumerateDOMObjectMap(gcProtectedMap());
enumerateGlobalHandles();
#endif
}
void V8GCController::checkMemoryUsage()
{
#if PLATFORM(CHROMIUM)
// These values are appropriate for Chromium only.
const int lowUsageMB = 256; // If memory usage is below this threshold, do not bother forcing GC.
const int highUsageMB = 1024; // If memory usage is above this threshold, force GC more aggresively.
const int highUsageDeltaMB = 128; // Delta of memory usage growth (vs. last workingSetEstimateMB) to force GC when memory usage is high.
int memoryUsageMB = getMemoryUsageInMB();
if ((memoryUsageMB > lowUsageMB && memoryUsageMB > 2 * workingSetEstimateMB) || (memoryUsageMB > highUsageMB && memoryUsageMB > workingSetEstimateMB + highUsageDeltaMB))
v8::V8::LowMemoryNotification();
#endif
}
} // namespace WebCore
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