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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "jswatchpoint.h"
#include "jsatom.h"
#include "jscompartment.h"
#include "jsfriendapi.h"
#include "gc/Marking.h"
#include "vm/Shape.h"
#include "jsgcinlines.h"
using namespace js;
using namespace js::gc;
inline HashNumber
WatchKeyHasher::hash(const Lookup& key)
{
return MovableCellHasher<PreBarrieredObject>::hash(key.object) ^ HashId(key.id);
}
namespace {
class AutoEntryHolder {
typedef WatchpointMap::Map Map;
Generation gen;
Map& map;
Map::Ptr p;
RootedObject obj;
RootedId id;
public:
AutoEntryHolder(JSContext* cx, Map& map, Map::Ptr p)
: gen(map.generation()), map(map), p(p), obj(cx, p->key().object), id(cx, p->key().id)
{
MOZ_ASSERT(!p->value().held);
p->value().held = true;
}
~AutoEntryHolder() {
if (gen != map.generation())
p = map.lookup(WatchKey(obj, id));
if (p)
p->value().held = false;
}
};
} /* anonymous namespace */
bool
WatchpointMap::init()
{
return map.init();
}
bool
WatchpointMap::watch(JSContext* cx, HandleObject obj, HandleId id,
JSWatchPointHandler handler, HandleObject closure)
{
MOZ_ASSERT(JSID_IS_STRING(id) || JSID_IS_INT(id) || JSID_IS_SYMBOL(id));
if (!obj->setWatched(cx))
return false;
Watchpoint w(handler, closure, false);
if (!map.put(WatchKey(obj, id), w)) {
ReportOutOfMemory(cx);
return false;
}
/*
* For generational GC, we don't need to post-barrier writes to the
* hashtable here because we mark all watchpoints as part of root marking in
* markAll().
*/
return true;
}
void
WatchpointMap::unwatch(JSObject* obj, jsid id,
JSWatchPointHandler* handlerp, JSObject** closurep)
{
if (Map::Ptr p = map.lookup(WatchKey(obj, id))) {
if (handlerp)
*handlerp = p->value().handler;
if (closurep) {
// Read barrier to prevent an incorrectly gray closure from escaping the
// watchpoint. See the comment before UnmarkGrayChildren in gc/Marking.cpp
JS::ExposeObjectToActiveJS(p->value().closure);
*closurep = p->value().closure;
}
map.remove(p);
}
}
void
WatchpointMap::unwatchObject(JSObject* obj)
{
for (Map::Enum e(map); !e.empty(); e.popFront()) {
Map::Entry& entry = e.front();
if (entry.key().object == obj)
e.removeFront();
}
}
void
WatchpointMap::clear()
{
map.clear();
}
bool
WatchpointMap::triggerWatchpoint(JSContext* cx, HandleObject obj, HandleId id, MutableHandleValue vp)
{
Map::Ptr p = map.lookup(WatchKey(obj, id));
if (!p || p->value().held)
return true;
AutoEntryHolder holder(cx, map, p);
/* Copy the entry, since GC would invalidate p. */
JSWatchPointHandler handler = p->value().handler;
RootedObject closure(cx, p->value().closure);
/* Determine the property's old value. */
Value old;
old.setUndefined();
if (obj->isNative()) {
NativeObject* nobj = &obj->as<NativeObject>();
if (Shape* shape = nobj->lookup(cx, id)) {
if (shape->hasSlot())
old = nobj->getSlot(shape->slot());
}
}
// Read barrier to prevent an incorrectly gray closure from escaping the
// watchpoint. See the comment before UnmarkGrayChildren in gc/Marking.cpp
JS::ExposeObjectToActiveJS(closure);
/* Call the handler. */
return handler(cx, obj, id, old, vp.address(), closure);
}
bool
WatchpointMap::markIteratively(JSTracer* trc)
{
bool marked = false;
for (Map::Enum e(map); !e.empty(); e.popFront()) {
Map::Entry& entry = e.front();
JSObject* priorKeyObj = entry.key().object;
jsid priorKeyId(entry.key().id.get());
bool objectIsLive =
IsMarked(trc->runtime(), const_cast<PreBarrieredObject*>(&entry.key().object));
if (objectIsLive || entry.value().held) {
if (!objectIsLive) {
TraceEdge(trc, const_cast<PreBarrieredObject*>(&entry.key().object),
"held Watchpoint object");
marked = true;
}
MOZ_ASSERT(JSID_IS_STRING(priorKeyId) ||
JSID_IS_INT(priorKeyId) ||
JSID_IS_SYMBOL(priorKeyId));
TraceEdge(trc, const_cast<PreBarrieredId*>(&entry.key().id), "WatchKey::id");
if (entry.value().closure && !IsMarked(trc->runtime(), &entry.value().closure)) {
TraceEdge(trc, &entry.value().closure, "Watchpoint::closure");
marked = true;
}
/* We will sweep this entry in sweepAll if !objectIsLive. */
if (priorKeyObj != entry.key().object || priorKeyId != entry.key().id)
e.rekeyFront(WatchKey(entry.key().object, entry.key().id));
}
}
return marked;
}
void
WatchpointMap::markAll(JSTracer* trc)
{
for (Map::Enum e(map); !e.empty(); e.popFront()) {
Map::Entry& entry = e.front();
WatchKey key = entry.key();
WatchKey prior = key;
MOZ_ASSERT(JSID_IS_STRING(prior.id) || JSID_IS_INT(prior.id) || JSID_IS_SYMBOL(prior.id));
TraceEdge(trc, const_cast<PreBarrieredObject*>(&key.object),
"held Watchpoint object");
TraceEdge(trc, const_cast<PreBarrieredId*>(&key.id), "WatchKey::id");
TraceEdge(trc, &entry.value().closure, "Watchpoint::closure");
if (prior.object != key.object || prior.id != key.id)
e.rekeyFront(key);
}
}
void
WatchpointMap::sweepAll(JSRuntime* rt)
{
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (WatchpointMap* wpmap = c->watchpointMap)
wpmap->sweep();
}
}
void
WatchpointMap::sweep()
{
for (Map::Enum e(map); !e.empty(); e.popFront()) {
Map::Entry& entry = e.front();
JSObject* obj(entry.key().object);
if (IsAboutToBeFinalizedUnbarriered(&obj)) {
MOZ_ASSERT(!entry.value().held);
e.removeFront();
} else if (obj != entry.key().object) {
e.rekeyFront(WatchKey(obj, entry.key().id));
}
}
}
void
WatchpointMap::traceAll(WeakMapTracer* trc)
{
JSRuntime* rt = trc->context;
for (CompartmentsIter comp(rt, SkipAtoms); !comp.done(); comp.next()) {
if (WatchpointMap* wpmap = comp->watchpointMap)
wpmap->trace(trc);
}
}
void
WatchpointMap::trace(WeakMapTracer* trc)
{
for (Map::Range r = map.all(); !r.empty(); r.popFront()) {
Map::Entry& entry = r.front();
trc->trace(nullptr,
JS::GCCellPtr(entry.key().object.get()),
JS::GCCellPtr(entry.value().closure.get()));
}
}
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