jsgc.c

java script test programing source code

    a->prev = arenaList->last;
    a->prevUnscanned = NULL;
    a->unscannedPages = 0;
    arenaList->last = a;
    arenaList->lastLimit = 0;

    bytesptr = (arenaList == &rt->gcArenaList[0])
               ? &rt->gcBytes
               : &rt->gcPrivateBytes;
    *bytesptr += GC_ARENA_SIZE;

    return JS_TRUE;
}

static void
DestroyGCArena(JSRuntime *rt, JSGCArenaList *arenaList, JSGCArena **ap)
{
    JSGCArena *a;
    uint32 *bytesptr;

    a = *ap;
    JS_ASSERT(a);
    bytesptr = (arenaList == &rt->gcArenaList[0])
               ? &rt->gcBytes
               : &rt->gcPrivateBytes;
    JS_ASSERT(*bytesptr >= GC_ARENA_SIZE);
    *bytesptr -= GC_ARENA_SIZE;
    METER(rt->gcStats.afree++);
    METER(--arenaList->stats.narenas);
    if (a == arenaList->last)
        arenaList->lastLimit = (uint16)(a->prev ? GC_THINGS_SIZE : 0);
    *ap = a->prev;

#ifdef DEBUG
    memset(a, JS_FREE_PATTERN, GC_ARENA_SIZE);
#endif
    free(a);
}

static void
InitGCArenaLists(JSRuntime *rt)
{
    uintN i, thingSize;
    JSGCArenaList *arenaList;

    for (i = 0; i < GC_NUM_FREELISTS; i++) {
        arenaList = &rt->gcArenaList[i];
        thingSize = GC_FREELIST_NBYTES(i);
        JS_ASSERT((size_t)(uint16)thingSize == thingSize);
        arenaList->last = NULL;
        arenaList->lastLimit = 0;
        arenaList->thingSize = (uint16)thingSize;
        arenaList->freeList = NULL;
        METER(memset(&arenaList->stats, 0, sizeof arenaList->stats));
    }
}

static void
FinishGCArenaLists(JSRuntime *rt)
{
    uintN i;
    JSGCArenaList *arenaList;

    for (i = 0; i < GC_NUM_FREELISTS; i++) {
        arenaList = &rt->gcArenaList[i];
        while (arenaList->last)
            DestroyGCArena(rt, arenaList, &arenaList->last);
        arenaList->freeList = NULL;
    }
}

uint8 *
js_GetGCThingFlags(void *thing)
{
    JSGCPageInfo *pi;
    jsuword offsetInArena, thingIndex;

    pi = THING_TO_PAGE(thing);
    offsetInArena = pi->offsetInArena;
    JS_ASSERT(offsetInArena < GC_THINGS_SIZE);
    thingIndex = ((offsetInArena & ~GC_PAGE_MASK) |
                  ((jsuword)thing & GC_PAGE_MASK)) / sizeof(JSGCThing);
    JS_ASSERT(thingIndex < GC_PAGE_SIZE);
    if (thingIndex >= (offsetInArena & GC_PAGE_MASK))
        thingIndex += GC_THINGS_SIZE;
    return (uint8 *)pi - offsetInArena + thingIndex;
}

JSRuntime*
js_GetGCStringRuntime(JSString *str)
{
    JSGCPageInfo *pi;
    JSGCArenaList *list;

    pi = THING_TO_PAGE(str);
    list = PAGE_TO_ARENA(pi)->list;

    JS_ASSERT(list->thingSize == sizeof(JSGCThing));
    JS_ASSERT(GC_FREELIST_INDEX(sizeof(JSGCThing)) == 0);

    return (JSRuntime *)((uint8 *)list - offsetof(JSRuntime, gcArenaList));
}

JSBool
js_IsAboutToBeFinalized(JSContext *cx, void *thing)
{
    uint8 flags = *js_GetGCThingFlags(thing);

    return !(flags & (GCF_MARK | GCF_LOCK | GCF_FINAL));
}

typedef void (*GCFinalizeOp)(JSContext *cx, JSGCThing *thing);

#ifndef DEBUG
# define js_FinalizeDouble       NULL
#endif

#if !JS_HAS_XML_SUPPORT
# define js_FinalizeXMLNamespace NULL
# define js_FinalizeXMLQName     NULL
# define js_FinalizeXML          NULL
#endif

static GCFinalizeOp gc_finalizers[GCX_NTYPES] = {
    (GCFinalizeOp) js_FinalizeObject,           /* GCX_OBJECT */
    (GCFinalizeOp) js_FinalizeString,           /* GCX_STRING */
    (GCFinalizeOp) js_FinalizeDouble,           /* GCX_DOUBLE */
    (GCFinalizeOp) js_FinalizeString,           /* GCX_MUTABLE_STRING */
    NULL,                                       /* GCX_PRIVATE */
    (GCFinalizeOp) js_FinalizeXMLNamespace,     /* GCX_NAMESPACE */
    (GCFinalizeOp) js_FinalizeXMLQName,         /* GCX_QNAME */
    (GCFinalizeOp) js_FinalizeXML,              /* GCX_XML */
    NULL,                                       /* GCX_EXTERNAL_STRING */
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

#ifdef GC_MARK_DEBUG
static const char newborn_external_string[] = "newborn external string";

static const char *gc_typenames[GCX_NTYPES] = {
    "newborn object",
    "newborn string",
    "newborn double",
    "newborn mutable string",
    "newborn private",
    "newborn Namespace",
    "newborn QName",
    "newborn XML",
    newborn_external_string,
    newborn_external_string,
    newborn_external_string,
    newborn_external_string,
    newborn_external_string,
    newborn_external_string,
    newborn_external_string,
    newborn_external_string
};
#endif

intN
js_ChangeExternalStringFinalizer(JSStringFinalizeOp oldop,
                                 JSStringFinalizeOp newop)
{
    uintN i;

    for (i = GCX_EXTERNAL_STRING; i < GCX_NTYPES; i++) {
        if (gc_finalizers[i] == (GCFinalizeOp) oldop) {
            gc_finalizers[i] = (GCFinalizeOp) newop;
            return (intN) i;
        }
    }
    return -1;
}

/* This is compatible with JSDHashEntryStub. */
typedef struct JSGCRootHashEntry {
    JSDHashEntryHdr hdr;
    void            *root;
    const char      *name;
} JSGCRootHashEntry;

/* Initial size of the gcRootsHash table (SWAG, small enough to amortize). */
#define GC_ROOTS_SIZE   256
#define GC_FINALIZE_LEN 1024

JSBool
js_InitGC(JSRuntime *rt, uint32 maxbytes)
{
    InitGCArenaLists(rt);
    if (!JS_DHashTableInit(&rt->gcRootsHash, JS_DHashGetStubOps(), NULL,
                           sizeof(JSGCRootHashEntry), GC_ROOTS_SIZE)) {
        rt->gcRootsHash.ops = NULL;
        return JS_FALSE;
    }
    rt->gcLocksHash = NULL;     /* create lazily */

    /*
     * Separate gcMaxMallocBytes from gcMaxBytes but initialize to maxbytes
     * for default backward API compatibility.
     */
    rt->gcMaxBytes = rt->gcMaxMallocBytes = maxbytes;

    return JS_TRUE;
}

#ifdef JS_GCMETER
JS_FRIEND_API(void)
js_DumpGCStats(JSRuntime *rt, FILE *fp)
{
    uintN i;
    size_t totalThings, totalMaxThings, totalBytes;

    fprintf(fp, "\nGC allocation statistics:\n");

#define UL(x)       ((unsigned long)(x))
#define ULSTAT(x)   UL(rt->gcStats.x)
    totalThings = 0;
    totalMaxThings = 0;
    totalBytes = 0;
    for (i = 0; i < GC_NUM_FREELISTS; i++) {
        JSGCArenaList *list = &rt->gcArenaList[i];
        JSGCArenaStats *stats = &list->stats;
        if (stats->maxarenas == 0) {
            fprintf(fp, "ARENA LIST %u (thing size %lu): NEVER USED\n",
                    i, UL(GC_FREELIST_NBYTES(i)));
            continue;
        }
        fprintf(fp, "ARENA LIST %u (thing size %lu):\n",
                i, UL(GC_FREELIST_NBYTES(i)));
        fprintf(fp, "                     arenas: %lu\n", UL(stats->narenas));
        fprintf(fp, "                 max arenas: %lu\n", UL(stats->maxarenas));
        fprintf(fp, "                     things: %lu\n", UL(stats->nthings));
        fprintf(fp, "                 max things: %lu\n", UL(stats->maxthings));
        fprintf(fp, "                  free list: %lu\n", UL(stats->freelen));
        fprintf(fp, "          free list density: %.1f%%\n",
                stats->narenas == 0
                ? 0.0
                : (100.0 * list->thingSize * (jsdouble)stats->freelen /
                   (GC_THINGS_SIZE * (jsdouble)stats->narenas)));
        fprintf(fp, "  average free list density: %.1f%%\n",
                stats->totalarenas == 0
                ? 0.0
                : (100.0 * list->thingSize * (jsdouble)stats->totalfreelen /
                   (GC_THINGS_SIZE * (jsdouble)stats->totalarenas)));
        fprintf(fp, "                   recycles: %lu\n", UL(stats->recycle));
        fprintf(fp, "        recycle/alloc ratio: %.2f\n",
                (jsdouble)stats->recycle /
                (jsdouble)(stats->totalnew - stats->recycle));
        totalThings += stats->nthings;
        totalMaxThings += stats->maxthings;
        totalBytes += GC_FREELIST_NBYTES(i) * stats->nthings;
    }
    fprintf(fp, "TOTAL STATS:\n");
    fprintf(fp, "     public bytes allocated: %lu\n", UL(rt->gcBytes));
    fprintf(fp, "    private bytes allocated: %lu\n", UL(rt->gcPrivateBytes));
    fprintf(fp, "             alloc attempts: %lu\n", ULSTAT(alloc));
#ifdef JS_THREADSAFE
    fprintf(fp, "        alloc without locks: %1u\n", ULSTAT(localalloc));
#endif
    fprintf(fp, "            total GC things: %lu\n", UL(totalThings));
    fprintf(fp, "        max total GC things: %lu\n", UL(totalMaxThings));
    fprintf(fp, "             GC things size: %lu\n", UL(totalBytes));
    fprintf(fp, "allocation retries after GC: %lu\n", ULSTAT(retry));
    fprintf(fp, "        allocation failures: %lu\n", ULSTAT(fail));
    fprintf(fp, "         things born locked: %lu\n", ULSTAT(lockborn));
    fprintf(fp, "           valid lock calls: %lu\n", ULSTAT(lock));
    fprintf(fp, "         valid unlock calls: %lu\n", ULSTAT(unlock));
    fprintf(fp, "       mark recursion depth: %lu\n", ULSTAT(depth));
    fprintf(fp, "     maximum mark recursion: %lu\n", ULSTAT(maxdepth));
    fprintf(fp, "     mark C recursion depth: %lu\n", ULSTAT(cdepth));
    fprintf(fp, "   maximum mark C recursion: %lu\n", ULSTAT(maxcdepth));
    fprintf(fp, "      delayed scan bag adds: %lu\n", ULSTAT(unscanned));
#ifdef DEBUG
    fprintf(fp, "  max delayed scan bag size: %lu\n", ULSTAT(maxunscanned));
#endif
    fprintf(fp, "   maximum GC nesting level: %lu\n", ULSTAT(maxlevel));
    fprintf(fp, "potentially useful GC calls: %lu\n", ULSTAT(poke));
    fprintf(fp, "           useless GC calls: %lu\n", ULSTAT(nopoke));
    fprintf(fp, "  thing arenas freed so far: %lu\n", ULSTAT(afree));
    fprintf(fp, "     stack segments scanned: %lu\n", ULSTAT(stackseg));
    fprintf(fp, "stack segment slots scanned: %lu\n", ULSTAT(segslots));
    fprintf(fp, "reachable closeable objects: %lu\n", ULSTAT(nclose));
    fprintf(fp, "    max reachable closeable: %lu\n", ULSTAT(maxnclose));
    fprintf(fp, "      scheduled close hooks: %lu\n", ULSTAT(closelater));
    fprintf(fp, "  max scheduled close hooks: %lu\n", ULSTAT(maxcloselater));
#undef UL
#undef US

#ifdef JS_ARENAMETER
    JS_DumpArenaStats(fp);
#endif
}
#endif

#ifdef DEBUG
static void
CheckLeakedRoots(JSRuntime *rt);
#endif

void
js_FinishGC(JSRuntime *rt)
{
#ifdef JS_ARENAMETER
    JS_DumpArenaStats(stdout);
#endif
#ifdef JS_GCMETER
    js_DumpGCStats(rt, stdout);
#endif

    FreePtrTable(&rt->gcIteratorTable, &iteratorTableInfo);
#if JS_HAS_GENERATORS
    rt->gcCloseState.reachableList = NULL;
    METER(rt->gcStats.nclose = 0);
    rt->gcCloseState.todoQueue = NULL;
#endif
    FinishGCArenaLists(rt);

    if (rt->gcRootsHash.ops) {
#ifdef DEBUG
        CheckLeakedRoots(rt);
#endif
        JS_DHashTableFinish(&rt->gcRootsHash);
        rt->gcRootsHash.ops = NULL;
    }
    if (rt->gcLocksHash) {
        JS_DHashTableDestroy(rt->gcLocksHash);
        rt->gcLocksHash = NULL;
    }
}

JSBool
js_AddRoot(JSContext *cx, void *rp, const char *name)
{
    JSBool ok = js_AddRootRT(cx->runtime, rp, name);
    if (!ok)
        JS_ReportOutOfMemory(cx);
    return ok;
}

JSBool
js_AddRootRT(JSRuntime *rt, void *rp, const char *name)
{
    JSBool ok;
    JSGCRootHashEntry *rhe;

    /*
     * Due to the long-standing, but now removed, use of rt->gcLock across the
     * bulk of js_GC, API users have come to depend on JS_AddRoot etc. locking
     * properly with a racing GC, without calling JS_AddRoot from a request.
     * We have to preserve API compatibility here, now that we avoid holding
     * rt->gcLock across the mark phase (including the root hashtable mark).
     *
     * If the GC is running and we're called on another thread, wait for this
     * GC activation to finish.  We can safely wait here (in the case where we
     * are called within a request on another thread's context) without fear
     * of deadlock because the GC doesn't set rt->gcRunning until after it has
     * waited for all active requests to end.
     */
    JS_LOCK_GC(rt);
#ifdef JS_THREADSAFE
    JS_ASSERT(!rt->gcRunning || rt->gcLevel > 0);
    if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
        do {
            JS_AWAIT_GC_DONE(rt);
        } while (rt->gcLevel > 0);
    }
#endif
    rhe = (JSGCRootHashEntry *) JS_DHashTableOperate(&rt->gcRootsHash, rp,
                                                     JS_DHASH_ADD);
    if (rhe) {
        rhe->root = rp;
        rhe->name = name;
        ok = JS_TRUE;
    } else {
        ok = JS_FALSE;
    }
    JS_UNLOCK_GC(rt);
    return ok;
}

JSBool
js_RemoveRoot(JSRuntime *rt, void *rp)
{
    /*
     * Due to the JS_RemoveRootRT API, we may be called outside of a request.
     * Same synchronization drill as above in js_AddRoot.
     */
    JS_LOCK_GC(rt);
#ifdef JS_THREADSAFE
    JS_ASSERT(!rt->gcRunning || rt->gcLevel > 0);
    if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
        do {
            JS_AWAIT_GC_DONE(rt);
        } while (rt->gcLevel > 0);
    }
#endif
    (void) JS_DHashTableOperate(&rt->gcRootsHash, rp, JS_DHASH_REMOVE);
    rt->gcPoke = JS_TRUE;
    JS_UNLOCK_GC(rt);
    return JS_TRUE;
}

#ifdef DEBUG

JS_STATIC_DLL_CALLBACK(JSDHashOperator)
js_root_printer(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 i, void *arg)
{