The Tor Browser: js/src/jswatchpoint.cpp@b8a032363ba2 (annotated)

js/src/jswatchpoint.cpp@b8a032363ba2 (annotated)

js/src/jswatchpoint.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- 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 "jsgcinlines.h"
 using namespace js;
 using namespace js::gc;
 inline HashNumber
 DefaultHasher<WatchKey>::hash(const Lookup &key)
 {
     return DefaultHasher<JSObject *>::hash(key.object.get()) ^ HashId(key.id.get());
 }
 namespace {
 class AutoEntryHolder {
     typedef WatchpointMap::Map Map;
     Map &map;
     Map::Ptr p;
     uint32_t gen;
     RootedObject obj;
     RootedId id;
   public:
     AutoEntryHolder(JSContext *cx, Map &map, Map::Ptr p)
       : map(map), p(p), gen(map.generation()), obj(cx, p->key().object), id(cx, p->key().id)
     {
         JS_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)
 {
     JS_ASSERT(JSID_IS_STRING(id) || JSID_IS_INT(id));
     if (!obj->setWatched(cx))
         return false;
     Watchpoint w(handler, closure, false);
     if (!map.put(WatchKey(obj, id), w)) {
         js_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::ExposeGCThingToActiveJS(p->value().closure, JSTRACE_OBJECT);
             *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()) {
         if (Shape *shape = obj->nativeLookup(cx, id)) {
             if (shape->hasSlot())
                 old = obj->nativeGetSlot(shape->slot());
         }
     }
     // Read barrier to prevent an incorrectly gray closure from escaping the
     // watchpoint. See the comment before UnmarkGrayChildren in gc/Marking.cpp
     JS::ExposeGCThingToActiveJS(closure, JSTRACE_OBJECT);
     /* Call the handler. */
     return handler(cx, obj, id, old, vp.address(), closure);
 }
 bool
 WatchpointMap::markCompartmentIteratively(JSCompartment *c, JSTracer *trc)
 {
     if (!c->watchpointMap)
         return false;
     return c->watchpointMap->markIteratively(trc);
 }
 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 =
             IsObjectMarked(const_cast<EncapsulatedPtrObject *>(&entry.key().object));
         if (objectIsLive || entry.value().held) {
             if (!objectIsLive) {
                 MarkObject(trc, const_cast<EncapsulatedPtrObject *>(&entry.key().object),
                            "held Watchpoint object");
                 marked = true;
             }
             JS_ASSERT(JSID_IS_STRING(priorKeyId) || JSID_IS_INT(priorKeyId));
             MarkId(trc, const_cast<EncapsulatedId *>(&entry.key().id), "WatchKey::id");
             if (entry.value().closure && !IsObjectMarked(&entry.value().closure)) {
                 MarkObject(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;
         JS_ASSERT(JSID_IS_STRING(prior.id) || JSID_IS_INT(prior.id));
         MarkObject(trc, const_cast<EncapsulatedPtrObject *>(&key.object),
                    "held Watchpoint object");
         MarkId(trc, const_cast<EncapsulatedId *>(&key.id), "WatchKey::id");
         MarkObject(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 (IsObjectAboutToBeFinalized(&obj)) {
             JS_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->runtime;
     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->callback(trc, nullptr,
                       entry.key().object.get(), JSTRACE_OBJECT,
                       entry.value().closure.get(), JSTRACE_OBJECT);
     }
 }

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js/src/jswatchpoint.cpp@b8a032363ba2 (annotated)

js/src/jswatchpoint.cpp