2011-04-16 21:23:44 -07:00
|
|
|
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
|
|
|
|
* vim: set ts=4 sw=4 et tw=99:
|
|
|
|
*
|
|
|
|
* ***** BEGIN LICENSE BLOCK *****
|
|
|
|
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
|
|
|
|
*
|
|
|
|
* The contents of this file are subject to the Mozilla Public License Version
|
|
|
|
* 1.1 (the "License"); you may not use this file except in compliance with
|
|
|
|
* the License. You may obtain a copy of the License at
|
|
|
|
* http://www.mozilla.org/MPL/
|
|
|
|
*
|
|
|
|
* Software distributed under the License is distributed on an "AS IS" basis,
|
|
|
|
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
|
|
|
|
* for the specific language governing rights and limitations under the
|
|
|
|
* License.
|
|
|
|
*
|
|
|
|
* The Original Code is Mozilla SpiderMonkey JavaScript 1.9 code, released
|
|
|
|
* May 28, 2008.
|
|
|
|
*
|
|
|
|
* The Initial Developer of the Original Code is
|
|
|
|
* Mozilla Foundation
|
|
|
|
* Portions created by the Initial Developer are Copyright (C) 2009
|
|
|
|
* the Initial Developer. All Rights Reserved.
|
|
|
|
*
|
|
|
|
* Contributor(s):
|
|
|
|
* Andreas Gal <gal@mozilla.com>
|
|
|
|
*
|
|
|
|
* Alternatively, the contents of this file may be used under the terms of
|
|
|
|
* either of the GNU General Public License Version 2 or later (the "GPL"),
|
|
|
|
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
|
|
|
|
* in which case the provisions of the GPL or the LGPL are applicable instead
|
|
|
|
* of those above. If you wish to allow use of your version of this file only
|
|
|
|
* under the terms of either the GPL or the LGPL, and not to allow others to
|
|
|
|
* use your version of this file under the terms of the MPL, indicate your
|
|
|
|
* decision by deleting the provisions above and replace them with the notice
|
|
|
|
* and other provisions required by the GPL or the LGPL. If you do not delete
|
|
|
|
* the provisions above, a recipient may use your version of this file under
|
|
|
|
* the terms of any one of the MPL, the GPL or the LGPL.
|
|
|
|
*
|
|
|
|
* ***** END LICENSE BLOCK ***** */
|
|
|
|
|
|
|
|
#ifndef jsweakmap_h___
|
|
|
|
#define jsweakmap_h___
|
|
|
|
|
|
|
|
#include "jsapi.h"
|
|
|
|
#include "jscntxt.h"
|
|
|
|
#include "jsobj.h"
|
|
|
|
|
|
|
|
namespace js {
|
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
// A subclass template of js::HashMap whose keys and values may be garbage-collected. When
|
|
|
|
// a key is collected, the table entry disappears, dropping its reference to the value.
|
|
|
|
//
|
|
|
|
// More precisely:
|
|
|
|
//
|
|
|
|
// A WeakMap entry is collected if and only if either the WeakMap or the entry's key
|
|
|
|
// is collected. If an entry is not collected, it remains in the WeakMap and it has a
|
|
|
|
// strong reference to the value.
|
|
|
|
//
|
|
|
|
// You must call this table's 'mark' method when the object of which it is a part is
|
|
|
|
// reached by the garbage collection tracer. Once a table is known to be live, the
|
|
|
|
// implementation takes care of the iterative marking needed for weak tables and removing
|
|
|
|
// table entries when collection is complete.
|
|
|
|
//
|
|
|
|
// You may provide your own MarkPolicy class to specify how keys and values are marked; a
|
|
|
|
// policy template provides default definitions for some common key/value type
|
|
|
|
// combinations.
|
|
|
|
//
|
|
|
|
// Details:
|
|
|
|
//
|
|
|
|
// The interface is as for a js::HashMap, with the following additions:
|
|
|
|
//
|
|
|
|
// - You must call the WeakMap's 'trace' member function when you discover that the map is
|
|
|
|
// part of a live object. (You'll typically call this from the containing type's 'trace'
|
|
|
|
// function.)
|
|
|
|
//
|
|
|
|
// - There is no AllocPolicy parameter; these are used with our garbage collector, so
|
|
|
|
// RuntimeAllocPolicy is hard-wired.
|
|
|
|
//
|
|
|
|
// - Optional fourth template parameter is a class MarkPolicy, with the following constructor:
|
|
|
|
//
|
|
|
|
// MarkPolicy(JSTracer *)
|
|
|
|
//
|
|
|
|
// and the following static member functions:
|
|
|
|
//
|
|
|
|
// bool keyMarked(Key &k)
|
|
|
|
// bool valueMarked(Value &v)
|
2011-06-29 02:27:47 -07:00
|
|
|
// Return true if k/v has been marked as live by the garbage collector.
|
2011-06-14 19:21:47 -07:00
|
|
|
//
|
2011-06-29 02:27:47 -07:00
|
|
|
// bool markEntryIfLive(Key &k, Value &v)
|
|
|
|
// If a table entry whose key is k should be retained, ensure its key and
|
|
|
|
// value are marked. Return true if any previously unmarked objects
|
|
|
|
// became marked.
|
|
|
|
//
|
|
|
|
// To ensure that the WeakMap's behavior isn't visibly affected by
|
|
|
|
// garbage collection, this should leave k unmarked only when no key
|
|
|
|
// matching k could ever be produced after this GC cycle completes ---
|
|
|
|
// removing entries whose keys this function leaves unmarked should never
|
|
|
|
// make future lookups fail.
|
|
|
|
//
|
|
|
|
// A typical definition of markIteratively would be:
|
|
|
|
//
|
|
|
|
// if (keyMarked(k) && !valueMarked(v)) {
|
|
|
|
// markObject(*v, "WeakMap entry value");
|
|
|
|
// return true;
|
|
|
|
// }
|
|
|
|
// return false;
|
|
|
|
//
|
|
|
|
// This meets the above constraint when, for example, Key is JSObject *:
|
|
|
|
// if k isn't marked, it won't exist once the collection cycle completes,
|
|
|
|
// and thus can't be supplied as a key.
|
|
|
|
//
|
|
|
|
// Note that this may mark entries where keyMarked(k) is not initially
|
|
|
|
// true. For example, you could have a table whose keys match when the
|
|
|
|
// values of one of their properties are equal: k1.x === k2.x. An entry
|
|
|
|
// in such a table could be live even when its key is not marked. The
|
|
|
|
// markEntryIfLive function for such a table would generally mark both k and v.
|
|
|
|
//
|
|
|
|
// void markEntry(Key &k, Value &v)
|
|
|
|
// Mark the table entry's key and value, k and v, as reachable by the
|
|
|
|
// collector. WeakMap uses this function for non-marking tracers: other
|
|
|
|
// code using the GC heap tracing functions to map the heap for some
|
|
|
|
// purpose or other.
|
|
|
|
//
|
|
|
|
// If omitted, the MarkPolicy parameter defaults to js::DefaultMarkPolicy<Key,
|
|
|
|
// Value>, a policy template with the obvious definitions for some typical
|
|
|
|
// SpiderMonkey type combinations.
|
2011-06-14 19:21:47 -07:00
|
|
|
|
|
|
|
// A policy template holding default marking algorithms for common type combinations. This
|
|
|
|
// provides default types for WeakMap's MarkPolicy template parameter.
|
|
|
|
template <class Key, class Value> class DefaultMarkPolicy;
|
|
|
|
|
|
|
|
// Common base class for all WeakMap specializations. The collector uses this to call
|
|
|
|
// their markIteratively and sweep methods.
|
|
|
|
class WeakMapBase {
|
|
|
|
public:
|
|
|
|
WeakMapBase() : next(NULL) { }
|
|
|
|
|
|
|
|
void trace(JSTracer *tracer) {
|
|
|
|
if (IS_GC_MARKING_TRACER(tracer)) {
|
|
|
|
// We don't do anything with a WeakMap at trace time. Rather, we wait until as
|
|
|
|
// many keys as possible have been marked, and add ourselves to the list of
|
|
|
|
// known-live WeakMaps to be scanned in the iterative marking phase, by
|
|
|
|
// markAllIteratively.
|
|
|
|
JSRuntime *rt = tracer->context->runtime;
|
|
|
|
next = rt->gcWeakMapList;
|
|
|
|
rt->gcWeakMapList = this;
|
|
|
|
} else {
|
|
|
|
// If we're not actually doing garbage collection, the keys won't be marked
|
|
|
|
// nicely as needed by the true ephemeral marking algorithm --- custom tracers
|
|
|
|
// must use their own means for cycle detection. So here we do a conservative
|
|
|
|
// approximation: pretend all keys are live.
|
|
|
|
nonMarkingTrace(tracer);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Garbage collector entry points.
|
|
|
|
|
|
|
|
// Check all weak maps that have been marked as live so far in this garbage
|
|
|
|
// collection, and mark the values of all entries that have become strong references
|
|
|
|
// to them. Return true if we marked any new values, indicating that we need to make
|
|
|
|
// another pass. In other words, mark my marked maps' marked members' mid-collection.
|
|
|
|
static bool markAllIteratively(JSTracer *tracer);
|
|
|
|
|
|
|
|
// Remove entries whose keys are dead from all weak maps marked as live in this
|
|
|
|
// garbage collection.
|
|
|
|
static void sweepAll(JSTracer *tracer);
|
2011-04-16 21:23:44 -07:00
|
|
|
|
|
|
|
protected:
|
2011-06-14 19:21:47 -07:00
|
|
|
// Instance member functions called by the above. Instantiations of WeakMap override
|
|
|
|
// these with definitions appropriate for their Key and Value types.
|
|
|
|
virtual void nonMarkingTrace(JSTracer *tracer) = 0;
|
|
|
|
virtual bool markIteratively(JSTracer *tracer) = 0;
|
|
|
|
virtual void sweep(JSTracer *tracer) = 0;
|
|
|
|
|
|
|
|
private:
|
|
|
|
// Link in a list of all the WeakMaps we have marked in this garbage collection,
|
|
|
|
// headed by JSRuntime::gcWeakMapList.
|
|
|
|
WeakMapBase *next;
|
|
|
|
};
|
2011-04-16 21:23:44 -07:00
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
template <class Key, class Value,
|
|
|
|
class HashPolicy = DefaultHasher<Key>,
|
|
|
|
class MarkPolicy = DefaultMarkPolicy<Key, Value> >
|
|
|
|
class WeakMap : public HashMap<Key, Value, HashPolicy, RuntimeAllocPolicy>, public WeakMapBase {
|
|
|
|
private:
|
|
|
|
typedef HashMap<Key, Value, HashPolicy, RuntimeAllocPolicy> Base;
|
|
|
|
typedef typename Base::Range Range;
|
|
|
|
typedef typename Base::Enum Enum;
|
2011-04-16 21:23:44 -07:00
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
public:
|
|
|
|
WeakMap(JSContext *cx) : Base(cx) { }
|
|
|
|
|
|
|
|
private:
|
|
|
|
void nonMarkingTrace(JSTracer *tracer) {
|
|
|
|
MarkPolicy t(tracer);
|
2011-06-29 02:27:47 -07:00
|
|
|
for (Range r = Base::all(); !r.empty(); r.popFront())
|
|
|
|
t.markEntry(r.front().key, r.front().value);
|
2011-06-14 19:21:47 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
bool markIteratively(JSTracer *tracer) {
|
|
|
|
MarkPolicy t(tracer);
|
|
|
|
bool markedAny = false;
|
|
|
|
for (Range r = Base::all(); !r.empty(); r.popFront()) {
|
2011-06-29 02:27:47 -07:00
|
|
|
/* If the entry is live, ensure its key and value are marked. */
|
|
|
|
if (t.markEntryIfLive(r.front().key, r.front().value)) {
|
2011-06-14 19:21:47 -07:00
|
|
|
/* We revived a value with children, we have to iterate again. */
|
|
|
|
markedAny = true;
|
|
|
|
}
|
2011-06-29 02:27:47 -07:00
|
|
|
JS_ASSERT_IF(t.keyMarked(r.front().key), t.valueMarked(r.front().value));
|
2011-06-14 19:21:47 -07:00
|
|
|
}
|
|
|
|
return markedAny;
|
|
|
|
}
|
|
|
|
|
|
|
|
void sweep(JSTracer *tracer) {
|
|
|
|
MarkPolicy t(tracer);
|
2011-06-29 02:27:47 -07:00
|
|
|
|
|
|
|
/* Remove all entries whose keys remain unmarked. */
|
2011-06-14 19:21:47 -07:00
|
|
|
for (Enum e(*this); !e.empty(); e.popFront()) {
|
|
|
|
if (!t.keyMarked(e.front().key))
|
|
|
|
e.removeFront();
|
|
|
|
}
|
2011-06-29 02:27:47 -07:00
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
#if DEBUG
|
2011-06-29 02:27:47 -07:00
|
|
|
/*
|
|
|
|
* Once we've swept, all remaining edges should stay within the
|
|
|
|
* known-live part of the graph.
|
|
|
|
*/
|
2011-06-14 19:21:47 -07:00
|
|
|
for (Range r = Base::all(); !r.empty(); r.popFront()) {
|
|
|
|
JS_ASSERT(t.keyMarked(r.front().key));
|
|
|
|
JS_ASSERT(t.valueMarked(r.front().value));
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
};
|
2011-04-16 21:23:44 -07:00
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
// Marking policy for maps from JSObject pointers to js::Values.
|
|
|
|
template <>
|
|
|
|
class DefaultMarkPolicy<JSObject *, Value> {
|
|
|
|
private:
|
|
|
|
JSTracer *tracer;
|
|
|
|
public:
|
|
|
|
DefaultMarkPolicy(JSTracer *t) : tracer(t) { }
|
|
|
|
bool keyMarked(JSObject *k) { return !IsAboutToBeFinalized(tracer->context, k); }
|
|
|
|
bool valueMarked(const Value &v) {
|
|
|
|
if (v.isMarkable())
|
|
|
|
return !IsAboutToBeFinalized(tracer->context, v.toGCThing());
|
2011-06-14 19:32:33 -07:00
|
|
|
return true;
|
2011-06-14 19:21:47 -07:00
|
|
|
}
|
2011-06-29 02:27:47 -07:00
|
|
|
bool markEntryIfLive(JSObject *k, const Value &v) {
|
|
|
|
if (keyMarked(k) && !valueMarked(v)) {
|
|
|
|
js::gc::MarkValue(tracer, v, "WeakMap entry value");
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
return false;
|
2011-06-14 19:21:47 -07:00
|
|
|
}
|
2011-06-29 02:27:47 -07:00
|
|
|
void markEntry(JSObject *k, const Value &v) {
|
|
|
|
js::gc::MarkObject(tracer, *k, "WeakMap entry key");
|
|
|
|
js::gc::MarkValue(tracer, v, "WeakMap entry value");
|
2011-06-14 19:21:47 -07:00
|
|
|
}
|
2011-04-16 21:23:44 -07:00
|
|
|
};
|
|
|
|
|
2011-06-14 19:21:47 -07:00
|
|
|
// The class of JavaScript WeakMap objects.
|
|
|
|
extern Class WeakMapClass;
|
|
|
|
|
2011-04-16 21:23:44 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
extern JSObject *
|
|
|
|
js_InitWeakMapClass(JSContext *cx, JSObject *obj);
|
|
|
|
|
|
|
|
#endif
|