1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2  * vim: set ts=8 sts=4 et sw=4 tw=99:
3  * This Source Code Form is subject to the terms of the Mozilla Public
4  * License, v. 2.0. If a copy of the MPL was not distributed with this
5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 #ifndef jswatchpoint_h
8 #define jswatchpoint_h
9 
10 #include "jsalloc.h"
11 
12 #include "gc/Barrier.h"
13 #include "js/HashTable.h"
14 
15 namespace js {
16 
17 struct WeakMapTracer;
18 
19 struct WatchKey {
WatchKeyWatchKey20     WatchKey() {}
WatchKeyWatchKey21     WatchKey(JSObject* obj, jsid id) : object(obj), id(id) {}
WatchKeyWatchKey22     WatchKey(const WatchKey& key) : object(key.object.get()), id(key.id.get()) {}
23 
24     // These are traced unconditionally during minor GC, so do not require
25     // post-barriers.
26     PreBarrieredObject object;
27     PreBarrieredId id;
28 
29     bool operator!=(const WatchKey& other) const {
30         return object != other.object || id != other.id;
31     }
32 };
33 
34 typedef bool
35 (* JSWatchPointHandler)(JSContext* cx, JSObject* obj, jsid id, JS::Value old,
36                         JS::Value* newp, void* closure);
37 
38 struct Watchpoint {
39     JSWatchPointHandler handler;
40     PreBarrieredObject closure;  /* This is always marked in minor GCs and so doesn't require a postbarrier. */
41     bool held;  /* true if currently running handler */
WatchpointWatchpoint42     Watchpoint(JSWatchPointHandler handler, JSObject* closure, bool held)
43       : handler(handler), closure(closure), held(held) {}
44 };
45 
46 struct WatchKeyHasher
47 {
48     typedef WatchKey Lookup;
49     static inline js::HashNumber hash(const Lookup& key);
50 
matchWatchKeyHasher51     static bool match(const WatchKey& k, const Lookup& l) {
52         return MovableCellHasher<PreBarrieredObject>::match(k.object, l.object) &&
53                DefaultHasher<PreBarrieredId>::match(k.id, l.id);
54     }
55 
rekeyWatchKeyHasher56     static void rekey(WatchKey& k, const WatchKey& newKey) {
57         k.object.unsafeSet(newKey.object);
58         k.id.unsafeSet(newKey.id);
59     }
60 };
61 
62 class WatchpointMap {
63   public:
64     typedef HashMap<WatchKey, Watchpoint, WatchKeyHasher, SystemAllocPolicy> Map;
65 
66     bool init();
67     bool watch(JSContext* cx, HandleObject obj, HandleId id,
68                JSWatchPointHandler handler, HandleObject closure);
69     void unwatch(JSObject* obj, jsid id,
70                  JSWatchPointHandler* handlerp, JSObject** closurep);
71     void unwatchObject(JSObject* obj);
72     void clear();
73 
74     bool triggerWatchpoint(JSContext* cx, HandleObject obj, HandleId id, MutableHandleValue vp);
75 
76     bool markIteratively(JSTracer* trc);
77     void markAll(JSTracer* trc);
78     static void sweepAll(JSRuntime* rt);
79     void sweep();
80 
81     static void traceAll(WeakMapTracer* trc);
82     void trace(WeakMapTracer* trc);
83 
84   private:
85     Map map;
86 };
87 
88 } // namespace js
89 
90 #endif /* jswatchpoint_h */
91