1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/jswatchpoint.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,249 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * vim: set ts=8 sts=4 et sw=4 tw=99:
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "jswatchpoint.h"
1.11 +
1.12 +#include "jsatom.h"
1.13 +#include "jscompartment.h"
1.14 +#include "jsfriendapi.h"
1.15 +
1.16 +#include "gc/Marking.h"
1.17 +
1.18 +#include "jsgcinlines.h"
1.19 +
1.20 +using namespace js;
1.21 +using namespace js::gc;
1.22 +
1.23 +inline HashNumber
1.24 +DefaultHasher<WatchKey>::hash(const Lookup &key)
1.25 +{
1.26 + return DefaultHasher<JSObject *>::hash(key.object.get()) ^ HashId(key.id.get());
1.27 +}
1.28 +
1.29 +namespace {
1.30 +
1.31 +class AutoEntryHolder {
1.32 + typedef WatchpointMap::Map Map;
1.33 + Map ↦
1.34 + Map::Ptr p;
1.35 + uint32_t gen;
1.36 + RootedObject obj;
1.37 + RootedId id;
1.38 +
1.39 + public:
1.40 + AutoEntryHolder(JSContext *cx, Map &map, Map::Ptr p)
1.41 + : map(map), p(p), gen(map.generation()), obj(cx, p->key().object), id(cx, p->key().id)
1.42 + {
1.43 + JS_ASSERT(!p->value().held);
1.44 + p->value().held = true;
1.45 + }
1.46 +
1.47 + ~AutoEntryHolder() {
1.48 + if (gen != map.generation())
1.49 + p = map.lookup(WatchKey(obj, id));
1.50 + if (p)
1.51 + p->value().held = false;
1.52 + }
1.53 +};
1.54 +
1.55 +} /* anonymous namespace */
1.56 +
1.57 +bool
1.58 +WatchpointMap::init()
1.59 +{
1.60 + return map.init();
1.61 +}
1.62 +
1.63 +bool
1.64 +WatchpointMap::watch(JSContext *cx, HandleObject obj, HandleId id,
1.65 + JSWatchPointHandler handler, HandleObject closure)
1.66 +{
1.67 + JS_ASSERT(JSID_IS_STRING(id) || JSID_IS_INT(id));
1.68 +
1.69 + if (!obj->setWatched(cx))
1.70 + return false;
1.71 +
1.72 + Watchpoint w(handler, closure, false);
1.73 + if (!map.put(WatchKey(obj, id), w)) {
1.74 + js_ReportOutOfMemory(cx);
1.75 + return false;
1.76 + }
1.77 + /*
1.78 + * For generational GC, we don't need to post-barrier writes to the
1.79 + * hashtable here because we mark all watchpoints as part of root marking in
1.80 + * markAll().
1.81 + */
1.82 + return true;
1.83 +}
1.84 +
1.85 +void
1.86 +WatchpointMap::unwatch(JSObject *obj, jsid id,
1.87 + JSWatchPointHandler *handlerp, JSObject **closurep)
1.88 +{
1.89 + if (Map::Ptr p = map.lookup(WatchKey(obj, id))) {
1.90 + if (handlerp)
1.91 + *handlerp = p->value().handler;
1.92 + if (closurep) {
1.93 + // Read barrier to prevent an incorrectly gray closure from escaping the
1.94 + // watchpoint. See the comment before UnmarkGrayChildren in gc/Marking.cpp
1.95 + JS::ExposeGCThingToActiveJS(p->value().closure, JSTRACE_OBJECT);
1.96 + *closurep = p->value().closure;
1.97 + }
1.98 + map.remove(p);
1.99 + }
1.100 +}
1.101 +
1.102 +void
1.103 +WatchpointMap::unwatchObject(JSObject *obj)
1.104 +{
1.105 + for (Map::Enum e(map); !e.empty(); e.popFront()) {
1.106 + Map::Entry &entry = e.front();
1.107 + if (entry.key().object == obj)
1.108 + e.removeFront();
1.109 + }
1.110 +}
1.111 +
1.112 +void
1.113 +WatchpointMap::clear()
1.114 +{
1.115 + map.clear();
1.116 +}
1.117 +
1.118 +bool
1.119 +WatchpointMap::triggerWatchpoint(JSContext *cx, HandleObject obj, HandleId id, MutableHandleValue vp)
1.120 +{
1.121 + Map::Ptr p = map.lookup(WatchKey(obj, id));
1.122 + if (!p || p->value().held)
1.123 + return true;
1.124 +
1.125 + AutoEntryHolder holder(cx, map, p);
1.126 +
1.127 + /* Copy the entry, since GC would invalidate p. */
1.128 + JSWatchPointHandler handler = p->value().handler;
1.129 + RootedObject closure(cx, p->value().closure);
1.130 +
1.131 + /* Determine the property's old value. */
1.132 + Value old;
1.133 + old.setUndefined();
1.134 + if (obj->isNative()) {
1.135 + if (Shape *shape = obj->nativeLookup(cx, id)) {
1.136 + if (shape->hasSlot())
1.137 + old = obj->nativeGetSlot(shape->slot());
1.138 + }
1.139 + }
1.140 +
1.141 + // Read barrier to prevent an incorrectly gray closure from escaping the
1.142 + // watchpoint. See the comment before UnmarkGrayChildren in gc/Marking.cpp
1.143 + JS::ExposeGCThingToActiveJS(closure, JSTRACE_OBJECT);
1.144 +
1.145 + /* Call the handler. */
1.146 + return handler(cx, obj, id, old, vp.address(), closure);
1.147 +}
1.148 +
1.149 +bool
1.150 +WatchpointMap::markCompartmentIteratively(JSCompartment *c, JSTracer *trc)
1.151 +{
1.152 + if (!c->watchpointMap)
1.153 + return false;
1.154 + return c->watchpointMap->markIteratively(trc);
1.155 +}
1.156 +
1.157 +bool
1.158 +WatchpointMap::markIteratively(JSTracer *trc)
1.159 +{
1.160 + bool marked = false;
1.161 + for (Map::Enum e(map); !e.empty(); e.popFront()) {
1.162 + Map::Entry &entry = e.front();
1.163 + JSObject *priorKeyObj = entry.key().object;
1.164 + jsid priorKeyId(entry.key().id.get());
1.165 + bool objectIsLive =
1.166 + IsObjectMarked(const_cast<EncapsulatedPtrObject *>(&entry.key().object));
1.167 + if (objectIsLive || entry.value().held) {
1.168 + if (!objectIsLive) {
1.169 + MarkObject(trc, const_cast<EncapsulatedPtrObject *>(&entry.key().object),
1.170 + "held Watchpoint object");
1.171 + marked = true;
1.172 + }
1.173 +
1.174 + JS_ASSERT(JSID_IS_STRING(priorKeyId) || JSID_IS_INT(priorKeyId));
1.175 + MarkId(trc, const_cast<EncapsulatedId *>(&entry.key().id), "WatchKey::id");
1.176 +
1.177 + if (entry.value().closure && !IsObjectMarked(&entry.value().closure)) {
1.178 + MarkObject(trc, &entry.value().closure, "Watchpoint::closure");
1.179 + marked = true;
1.180 + }
1.181 +
1.182 + /* We will sweep this entry in sweepAll if !objectIsLive. */
1.183 + if (priorKeyObj != entry.key().object || priorKeyId != entry.key().id)
1.184 + e.rekeyFront(WatchKey(entry.key().object, entry.key().id));
1.185 + }
1.186 + }
1.187 + return marked;
1.188 +}
1.189 +
1.190 +void
1.191 +WatchpointMap::markAll(JSTracer *trc)
1.192 +{
1.193 + for (Map::Enum e(map); !e.empty(); e.popFront()) {
1.194 + Map::Entry &entry = e.front();
1.195 + WatchKey key = entry.key();
1.196 + WatchKey prior = key;
1.197 + JS_ASSERT(JSID_IS_STRING(prior.id) || JSID_IS_INT(prior.id));
1.198 +
1.199 + MarkObject(trc, const_cast<EncapsulatedPtrObject *>(&key.object),
1.200 + "held Watchpoint object");
1.201 + MarkId(trc, const_cast<EncapsulatedId *>(&key.id), "WatchKey::id");
1.202 + MarkObject(trc, &entry.value().closure, "Watchpoint::closure");
1.203 +
1.204 + if (prior.object != key.object || prior.id != key.id)
1.205 + e.rekeyFront(key);
1.206 + }
1.207 +}
1.208 +
1.209 +void
1.210 +WatchpointMap::sweepAll(JSRuntime *rt)
1.211 +{
1.212 + for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
1.213 + if (WatchpointMap *wpmap = c->watchpointMap)
1.214 + wpmap->sweep();
1.215 + }
1.216 +}
1.217 +
1.218 +void
1.219 +WatchpointMap::sweep()
1.220 +{
1.221 + for (Map::Enum e(map); !e.empty(); e.popFront()) {
1.222 + Map::Entry &entry = e.front();
1.223 + JSObject *obj(entry.key().object);
1.224 + if (IsObjectAboutToBeFinalized(&obj)) {
1.225 + JS_ASSERT(!entry.value().held);
1.226 + e.removeFront();
1.227 + } else if (obj != entry.key().object) {
1.228 + e.rekeyFront(WatchKey(obj, entry.key().id));
1.229 + }
1.230 + }
1.231 +}
1.232 +
1.233 +void
1.234 +WatchpointMap::traceAll(WeakMapTracer *trc)
1.235 +{
1.236 + JSRuntime *rt = trc->runtime;
1.237 + for (CompartmentsIter comp(rt, SkipAtoms); !comp.done(); comp.next()) {
1.238 + if (WatchpointMap *wpmap = comp->watchpointMap)
1.239 + wpmap->trace(trc);
1.240 + }
1.241 +}
1.242 +
1.243 +void
1.244 +WatchpointMap::trace(WeakMapTracer *trc)
1.245 +{
1.246 + for (Map::Range r = map.all(); !r.empty(); r.popFront()) {
1.247 + Map::Entry &entry = r.front();
1.248 + trc->callback(trc, nullptr,
1.249 + entry.key().object.get(), JSTRACE_OBJECT,
1.250 + entry.value().closure.get(), JSTRACE_OBJECT);
1.251 + }
1.252 +}
