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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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
* 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 Communicator client code, released
* March 31, 1998.
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
* Contributor(s):
* 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 jsgc_h___
#define jsgc_h___
* JS Garbage Collector.
#include "jsprvtd.h"
#include "jspubtd.h"
#include "jsdhash.h"
#include "jsbit.h"
#include "jsutil.h"
#include "jstask.h"
#define JSTRACE_XML 3
* One past the maximum trace kind.
* Get the type of the external string or -1 if the string was not created
* with JS_NewExternalString.
extern intN
js_GetExternalStringGCType(JSString *str);
extern JS_FRIEND_API(uint32)
js_GetGCThingTraceKind(void *thing);
* The sole purpose of the function is to preserve public API compatibility
* in JS_GetStringBytes which takes only single JSString* argument.
js_GetGCStringRuntime(JSString *str);
#if 1
* Since we're forcing a GC from JS_GC anyway, don't bother wasting cycles
* loading oldval. XXX remove implied force, fix jsinterp.c's "second arg
* ignored", etc.
#define GC_POKE(cx, oldval) ((cx)->runtime->gcPoke = JS_TRUE)
#define GC_POKE(cx, oldval) ((cx)->runtime->gcPoke = JSVAL_IS_GCTHING(oldval))
extern JSBool
js_InitGC(JSRuntime *rt, uint32 maxbytes);
extern void
js_FinishGC(JSRuntime *rt);
extern intN
js_ChangeExternalStringFinalizer(JSStringFinalizeOp oldop,
JSStringFinalizeOp newop);
extern JSBool
js_AddRoot(JSContext *cx, void *rp, const char *name);
extern JSBool
js_AddRootRT(JSRuntime *rt, void *rp, const char *name);
extern JSBool
js_RemoveRoot(JSRuntime *rt, void *rp);
#ifdef DEBUG
extern void
js_DumpNamedRoots(JSRuntime *rt,
void (*dump)(const char *name, void *rp, void *data),
void *data);
extern uint32
js_MapGCRoots(JSRuntime *rt, JSGCRootMapFun map, void *data);
/* Table of pointers with count valid members. */
typedef struct JSPtrTable {
size_t count;
void **array;
} JSPtrTable;
extern JSBool
js_RegisterCloseableIterator(JSContext *cx, JSObject *obj);
* Allocate a new double jsval and store the result in *vp. vp must be a root.
* The function does not copy the result into any weak root.
extern JSBool
js_NewDoubleInRootedValue(JSContext *cx, jsdouble d, jsval *vp);
* Return a pointer to a new GC-allocated and weakly-rooted jsdouble number,
* or null when the allocation fails.
extern jsdouble *
js_NewWeaklyRootedDouble(JSContext *cx, jsdouble d);
#ifdef JS_TRACER
extern JSBool
js_ReserveObjects(JSContext *cx, size_t nobjects);
extern JSBool
js_LockGCThingRT(JSRuntime *rt, void *thing);
extern void
js_UnlockGCThingRT(JSRuntime *rt, void *thing);
extern bool
js_IsAboutToBeFinalized(void *thing);
* Macro to test if a traversal is the marking phase of GC to avoid exposing
* ScriptFilenameEntry to traversal implementations.
#define IS_GC_MARKING_TRACER(trc) ((trc)->callback == NULL)
# define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) < JSTRACE_LIMIT)
# define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) <= JSTRACE_STRING)
* Trace jsval when JSVAL_IS_OBJECT(v) can be a GC thing pointer tagged as a
* jsval. NB: punning an arbitrary JSString * as an untagged (object-tagged)
* jsval no longer works due to static int and unit strings!
extern void
js_CallValueTracerIfGCThing(JSTracer *trc, jsval v);
extern void
js_TraceStackFrame(JSTracer *trc, JSStackFrame *fp);
js_TraceRuntime(JSTracer *trc, JSBool allAtoms);
js_TraceContext(JSTracer *trc, JSContext *acx);
* Schedule the GC call at a later safe point.
# define js_TriggerGC(cx, gcLocked) js_TriggerGC (cx)
extern void
js_TriggerGC(JSContext *cx, JSBool gcLocked);
* Kinds of js_GC invocation.
typedef enum JSGCInvocationKind {
/* Normal invocation. */
* Called from js_DestroyContext for last JSContext in a JSRuntime, when
* it is imperative that rt->gcPoke gets cleared early in js_GC.
* Flag bit telling js_GC that the caller has already acquired rt->gcLock.
* Currently, this flag is set for the invocation kinds that also preserve
* atoms and weak roots, so we don't need another bit for GC_KEEP_ATOMS.
GC_LOCK_HELD = 0x10,
* Called from js_SetProtoOrParent with a request to set an object's proto
* or parent slot inserted on rt->setSlotRequests.
* Called from js_NewGCThing as a last-ditch GC attempt. See comments in
* jsgc.c just before js_GC's definition for details.
} JSGCInvocationKind;
extern void
js_GC(JSContext *cx, JSGCInvocationKind gckind);
extern void
js_CallGCMarker(JSTracer *trc, void *thing, uint32 kind);
* The kind of GC thing with a finalizer. The external strings follow the
* ordinary string to simplify js_GetExternalStringGCType.
enum JSFinalizeGCThingKind {
static inline bool
IsFinalizableStringKind(unsigned thingKind)
return unsigned(FINALIZE_STRING) <= thingKind &&
* Allocates a new GC thing. After a successful allocation the caller must
* fully initialize the thing before calling any function that can potentially
* trigger GC. This will ensure that GC tracing never sees junk values stored
* in the partially initialized thing.
extern void *
js_NewFinalizableGCThing(JSContext *cx, unsigned thingKind);
static inline JSObject *
js_NewGCObject(JSContext *cx)
return (JSObject *) js_NewFinalizableGCThing(cx, FINALIZE_OBJECT);
static inline JSString *
js_NewGCString(JSContext *cx)
return (JSString *) js_NewFinalizableGCThing(cx, FINALIZE_STRING);
static inline JSString *
js_NewGCExternalString(JSContext *cx, uintN type)
return (JSString *) js_NewFinalizableGCThing(cx, type);
static inline JSFunction*
js_NewGCFunction(JSContext *cx)
return (JSFunction *) js_NewFinalizableGCThing(cx, FINALIZE_FUNCTION);
static inline JSXML *
js_NewGCXML(JSContext *cx)
return (JSXML *) js_NewFinalizableGCThing(cx, FINALIZE_XML);
struct JSGCArena;
struct JSGCChunkInfo;
struct JSGCArenaList {
JSGCArena *head; /* list start */
JSGCArena *cursor; /* arena with free things */
uint32 thingKind; /* one of JSFinalizeGCThingKind */
uint32 thingSize; /* size of things to allocate on this list
struct JSGCDoubleArenaList {
JSGCArena *head; /* list start */
JSGCArena *cursor; /* next arena with free cells */
struct JSGCFreeLists {
JSGCThing *doubles;
JSGCThing *finalizables[FINALIZE_LIMIT];
void purge();
void moveTo(JSGCFreeLists * another);
#ifdef DEBUG
bool isEmpty() const {
if (doubles)
return false;
for (size_t i = 0; i != JS_ARRAY_LENGTH(finalizables); ++i) {
if (finalizables[i])
return false;
return true;
extern void
js_DestroyScriptsToGC(JSContext *cx, JSThreadData *data);
struct JSWeakRoots {
/* Most recently created things by type, members of the GC's root set. */
void *finalizableNewborns[FINALIZE_LIMIT];
jsdouble *newbornDouble;
/* Atom root for the last-looked-up atom on this context. */
jsval lastAtom;
/* Root for the result of the most recent js_InternalInvoke call. */
jsval lastInternalResult;
void mark(JSTracer *trc);
#define JS_CLEAR_WEAK_ROOTS(wr) (memset((wr), 0, sizeof(JSWeakRoots)))
class JSFreePointerListTask : public JSBackgroundTask {
void *head;
JSFreePointerListTask() : head(NULL) {}
void add(void* ptr) {
*(void**)ptr = head;
head = ptr;
void run() {
void *ptr = head;
while (ptr) {
void *next = *(void **)ptr;
ptr = next;
extern void
js_FinalizeStringRT(JSRuntime *rt, JSString *str);
#if defined JS_GCMETER
const bool JS_WANT_GC_METER_PRINT = true;
#elif defined DEBUG
# define JS_GCMETER 1
const bool JS_WANT_GC_METER_PRINT = false;
struct JSGCArenaStats {
uint32 alloc; /* allocation attempts */
uint32 localalloc; /* allocations from local lists */
uint32 retry; /* allocation retries after running the GC */
uint32 fail; /* allocation failures */
uint32 nthings; /* live GC things */
uint32 maxthings; /* maximum of live GC cells */
double totalthings; /* live GC things the GC scanned so far */
uint32 narenas; /* number of arena in list before the GC */
uint32 newarenas; /* new arenas allocated before the last GC */
uint32 livearenas; /* number of live arenas after the last GC */
uint32 maxarenas; /* maximum of allocated arenas */
uint32 totalarenas; /* total number of arenas with live things that
GC scanned so far */
struct JSGCStats {
uint32 finalfail; /* finalizer calls allocator failures */
uint32 lockborn; /* things born locked */
uint32 lock; /* valid lock calls */
uint32 unlock; /* valid unlock calls */
uint32 depth; /* mark tail recursion depth */
uint32 maxdepth; /* maximum mark tail recursion depth */
uint32 cdepth; /* mark recursion depth of C functions */
uint32 maxcdepth; /* maximum mark recursion depth of C functions */
uint32 unmarked; /* number of times marking of GC thing's children were
delayed due to a low C stack */
#ifdef DEBUG
uint32 maxunmarked;/* maximum number of things with children to mark
later */
uint32 maxlevel; /* maximum GC nesting (indirect recursion) level */
uint32 poke; /* number of potentially useful GC calls */
uint32 afree; /* thing arenas freed so far */
uint32 stackseg; /* total extraordinary stack segments scanned */
uint32 segslots; /* total stack segment jsval slots scanned */
uint32 nclose; /* number of objects with close hooks */
uint32 maxnclose; /* max number of objects with close hooks */
uint32 closelater; /* number of close hooks scheduled to run */
uint32 maxcloselater; /* max number of close hooks scheduled to run */
JSGCArenaStats arenaStats[FINALIZE_LIMIT];
JSGCArenaStats doubleArenaStats;
extern JS_FRIEND_API(void)
js_DumpGCStats(JSRuntime *rt, FILE *fp);
#endif /* JS_GCMETER */
* This function is defined in jsdbgapi.cpp but is declared here to avoid
* polluting jsdbgapi.h, a public API header, with internal functions.
extern void
js_MarkTraps(JSTracer *trc);
#endif /* jsgc_h___ */
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