/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * ***** 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 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 #include "jstypes.h" #include "jsprvtd.h" #include "jspubtd.h" #include "jsdhash.h" #include "jsbit.h" #include "jsutil.h" #include "jstask.h" #include "jsvector.h" #include "jsversion.h" #define JSTRACE_XML 3 /* * One past the maximum trace kind. */ #define JSTRACE_LIMIT 4 const uintN JS_EXTERNAL_STRING_LIMIT = 8; /* * 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. */ JSRuntime * js_GetGCThingRuntime(void *thing); #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) #else #define GC_POKE(cx, oldval) ((cx)->runtime->gcPoke = JSVAL_IS_GCTHING(oldval)) #endif 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); #endif 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); #endif 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) #if JS_HAS_XML_SUPPORT # define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) < JSTRACE_LIMIT) #else # define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) <= JSTRACE_STRING) #endif /* * 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); extern JS_REQUIRES_STACK void js_TraceRuntime(JSTracer *trc); extern JS_REQUIRES_STACK JS_FRIEND_API(void) js_TraceContext(JSTracer *trc, JSContext *acx); /* * Schedule the GC call at a later safe point. */ #ifndef JS_THREADSAFE # define js_TriggerGC(cx, gcLocked) js_TriggerGC (cx) #endif extern void js_TriggerGC(JSContext *cx, JSBool gcLocked); /* * Kinds of js_GC invocation. */ typedef enum JSGCInvocationKind { /* Normal invocation. */ GC_NORMAL = 0, /* * Called from js_DestroyContext for last JSContext in a JSRuntime, when * it is imperative that rt->gcPoke gets cleared early in js_GC. */ GC_LAST_CONTEXT = 1, /* * Flag bit telling js_GC that the caller has already acquired rt->gcLock. */ GC_LOCK_HELD = 0x10 } JSGCInvocationKind; extern void js_GC(JSContext *cx, JSGCInvocationKind gckind); /* * Set object's prototype or parent slot while checking that doing so would * not create a cycle in the proto or parent chain. The cycle check and slot * change are done only when all other requests are finished or suspended to * ensure exclusive access to the chain. If there is a cycle, return false * without reporting an error. Otherwise, set the proto or parent and return * true. */ extern bool js_SetProtoOrParentCheckingForCycles(JSContext *cx, JSObject *obj, uint32 slot, JSObject *pobj); #ifdef JS_THREADSAFE /* * This is a helper for code at can potentially run outside JS request to * ensure that the GC is not running when the function returns. * * This function must be called with the GC lock held. */ extern void js_WaitForGC(JSRuntime *rt); #else /* !JS_THREADSAFE */ # define js_WaitForGC(rt) ((void) 0) #endif 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 { FINALIZE_OBJECT, FINALIZE_FUNCTION, #if JS_HAS_XML_SUPPORT FINALIZE_XML, #endif FINALIZE_STRING, FINALIZE_EXTERNAL_STRING0, FINALIZE_EXTERNAL_STRING1, FINALIZE_EXTERNAL_STRING2, FINALIZE_EXTERNAL_STRING3, FINALIZE_EXTERNAL_STRING4, FINALIZE_EXTERNAL_STRING5, FINALIZE_EXTERNAL_STRING6, FINALIZE_EXTERNAL_STRING7, FINALIZE_EXTERNAL_STRING_LAST = FINALIZE_EXTERNAL_STRING7, FINALIZE_LIMIT }; static inline bool IsFinalizableStringKind(unsigned thingKind) { return unsigned(FINALIZE_STRING) <= thingKind && thingKind <= unsigned(FINALIZE_EXTERNAL_STRING_LAST); } /* * 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) { JS_ASSERT(type < JS_EXTERNAL_STRING_LIMIT); type += FINALIZE_EXTERNAL_STRING0; return (JSString *) js_NewFinalizableGCThing(cx, type); } static inline JSFunction* js_NewGCFunction(JSContext *cx) { return (JSFunction *) js_NewFinalizableGCThing(cx, FINALIZE_FUNCTION); } #if JS_HAS_XML_SUPPORT static inline JSXML * js_NewGCXML(JSContext *cx) { return (JSXML *) js_NewFinalizableGCThing(cx, FINALIZE_XML); } #endif 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; } #endif }; 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))) namespace js { #ifdef JS_THREADSAFE /* * During the finalization we do not free immediately. Rather we add the * corresponding pointers to a buffer which we later release on the * background thread. * * The buffer is implemented as a vector of 64K arrays of pointers, not as a * simple vector, to avoid realloc calls during the vector growth and to not * bloat the binary size of the inlined freeLater method. Any OOM during * buffer growth results in the pointer being freed immediately. */ class BackgroundSweepTask : public JSBackgroundTask { static const size_t FREE_ARRAY_SIZE = size_t(1) << 16; static const size_t FREE_ARRAY_LENGTH = FREE_ARRAY_SIZE / sizeof(void *); Vector freeVector; void **freeCursor; void **freeCursorEnd; JS_FRIEND_API(void) replenishAndFreeLater(void *ptr); static void freeElementsAndArray(void **array, void **end) { JS_ASSERT(array <= end); for (void **p = array; p != end; ++p) js_free(*p); js_free(array); } public: BackgroundSweepTask() : freeCursor(NULL), freeCursorEnd(NULL) { } void freeLater(void* ptr) { if (freeCursor != freeCursorEnd) *freeCursor++ = ptr; else replenishAndFreeLater(ptr); } virtual void run(); }; #endif /* JS_THREADSAFE */ struct ConservativeGCThreadData { /* * The GC scans conservatively between JSThreadData::nativeStackBase and * nativeStackTop unless the latter is NULL. */ jsuword *nativeStackTop; union { jmp_buf jmpbuf; jsuword words[JS_HOWMANY(sizeof(jmp_buf), sizeof(jsuword))]; } registerSnapshot; size_t enableCount; JS_NEVER_INLINE void enable(bool knownStackBoundary = false); void disable(); }; } /* namespace js */ #define JS_DUMP_CONSERVATIVE_GC_ROOTS 1 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; #endif #if defined JS_GCMETER || defined JS_DUMP_CONSERVATIVE_GC_ROOTS struct JSConservativeGCStats { uint32 words; /* number of words on native stacks */ uint32 unique; /* number of unique words */ uint32 oddaddress; /* excluded because low bit was set */ uint32 outside; /* not within chunk min/max address range */ uint32 notchunk; /* not within a valid chunk */ uint32 notarena; /* not within non-free arena */ uint32 wrongtag; /* tagged pointer but wrong type */ uint32 notlive; /* gcthing is not allocated */ uint32 gcthings; /* number of live gcthings */ uint32 raw; /* number of raw pointers marked */ uint32 unmarked; /* number of unmarked gc things discovered on the stack */ }; #endif #ifdef JS_GCMETER 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 */ #endif 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 */ uint32 nallarenas; /* number of all allocated arenas */ uint32 maxnallarenas; /* maximum number of all allocated arenas */ uint32 nchunks; /* number of allocated chunks */ uint32 maxnchunks; /* maximum number of allocated chunks */ JSGCArenaStats arenaStats[FINALIZE_LIMIT]; JSGCArenaStats doubleArenaStats; JSConservativeGCStats conservative; }; 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); namespace js { void TraceObjectVector(JSTracer *trc, JSObject **vec, uint32 len); inline void TraceValues(JSTracer *trc, jsval *beg, jsval *end, const char *name) { for (jsval *vp = beg; vp < end; ++vp) { jsval v = *vp; if (JSVAL_IS_TRACEABLE(v)) { JS_SET_TRACING_INDEX(trc, name, vp - beg); js_CallGCMarker(trc, JSVAL_TO_TRACEABLE(v), JSVAL_TRACE_KIND(v)); } } } inline void TraceValues(JSTracer *trc, size_t len, jsval *vec, const char *name) { TraceValues(trc, vec, vec + len, name); } } /* namespace js */ #endif /* jsgc_h___ */