jscntxt.c

来自「java script test programing source code」· C语言 代码 · 共 1,230 行 · 第 1/3 页

            JS_MaybeGC(cx);
    }

    /* Free the stuff hanging off of cx. */
    JS_FinishArenaPool(&cx->stackPool);
    JS_FinishArenaPool(&cx->tempPool);

    if (cx->lastMessage)
        free(cx->lastMessage);

    /* Remove any argument formatters. */
    map = cx->argumentFormatMap;
    while (map) {
        JSArgumentFormatMap *temp = map;
        map = map->next;
        JS_free(cx, temp);
    }

    /* Destroy the resolve recursion damper. */
    if (cx->resolvingTable) {
        JS_DHashTableDestroy(cx->resolvingTable);
        cx->resolvingTable = NULL;
    }

    lrs = cx->localRootStack;
    if (lrs) {
        while ((lrc = lrs->topChunk) != &lrs->firstChunk) {
            lrs->topChunk = lrc->down;
            JS_free(cx, lrc);
        }
        JS_free(cx, lrs);
    }

#ifdef JS_THREADSAFE
    js_ClearContextThread(cx);
#endif

    /* Finally, free cx itself. */
    free(cx);
}

JSBool
js_ValidContextPointer(JSRuntime *rt, JSContext *cx)
{
    JSCList *cl;

    for (cl = rt->contextList.next; cl != &rt->contextList; cl = cl->next) {
        if (cl == &cx->links)
            return JS_TRUE;
    }
    JS_RUNTIME_METER(rt, deadContexts);
    return JS_FALSE;
}

JSContext *
js_ContextIterator(JSRuntime *rt, JSBool unlocked, JSContext **iterp)
{
    JSContext *cx = *iterp;

    if (unlocked)
        JS_LOCK_GC(rt);
    if (!cx)
        cx = (JSContext *)&rt->contextList;
    cx = (JSContext *)cx->links.next;
    if (&cx->links == &rt->contextList)
        cx = NULL;
    *iterp = cx;
    if (unlocked)
        JS_UNLOCK_GC(rt);
    return cx;
}

JS_STATIC_DLL_CALLBACK(const void *)
resolving_GetKey(JSDHashTable *table, JSDHashEntryHdr *hdr)
{
    JSResolvingEntry *entry = (JSResolvingEntry *)hdr;

    return &entry->key;
}

JS_STATIC_DLL_CALLBACK(JSDHashNumber)
resolving_HashKey(JSDHashTable *table, const void *ptr)
{
    const JSResolvingKey *key = (const JSResolvingKey *)ptr;

    return ((JSDHashNumber)JS_PTR_TO_UINT32(key->obj) >> JSVAL_TAGBITS) ^ key->id;
}

JS_PUBLIC_API(JSBool)
resolving_MatchEntry(JSDHashTable *table,
                     const JSDHashEntryHdr *hdr,
                     const void *ptr)
{
    const JSResolvingEntry *entry = (const JSResolvingEntry *)hdr;
    const JSResolvingKey *key = (const JSResolvingKey *)ptr;

    return entry->key.obj == key->obj && entry->key.id == key->id;
}

static const JSDHashTableOps resolving_dhash_ops = {
    JS_DHashAllocTable,
    JS_DHashFreeTable,
    resolving_GetKey,
    resolving_HashKey,
    resolving_MatchEntry,
    JS_DHashMoveEntryStub,
    JS_DHashClearEntryStub,
    JS_DHashFinalizeStub,
    NULL
};

JSBool
js_StartResolving(JSContext *cx, JSResolvingKey *key, uint32 flag,
                  JSResolvingEntry **entryp)
{
    JSDHashTable *table;
    JSResolvingEntry *entry;

    table = cx->resolvingTable;
    if (!table) {
        table = JS_NewDHashTable(&resolving_dhash_ops, NULL,
                                 sizeof(JSResolvingEntry),
                                 JS_DHASH_MIN_SIZE);
        if (!table)
            goto outofmem;
        cx->resolvingTable = table;
    }

    entry = (JSResolvingEntry *)
            JS_DHashTableOperate(table, key, JS_DHASH_ADD);
    if (!entry)
        goto outofmem;

    if (entry->flags & flag) {
        /* An entry for (key, flag) exists already -- dampen recursion. */
        entry = NULL;
    } else {
        /* Fill in key if we were the first to add entry, then set flag. */
        if (!entry->key.obj)
            entry->key = *key;
        entry->flags |= flag;
    }
    *entryp = entry;
    return JS_TRUE;

outofmem:
    JS_ReportOutOfMemory(cx);
    return JS_FALSE;
}

void
js_StopResolving(JSContext *cx, JSResolvingKey *key, uint32 flag,
                 JSResolvingEntry *entry, uint32 generation)
{
    JSDHashTable *table;

    /*
     * Clear flag from entry->flags and return early if other flags remain.
     * We must take care to re-lookup entry if the table has changed since
     * it was found by js_StartResolving.
     */
    table = cx->resolvingTable;
    if (!entry || table->generation != generation) {
        entry = (JSResolvingEntry *)
                JS_DHashTableOperate(table, key, JS_DHASH_LOOKUP);
    }
    JS_ASSERT(JS_DHASH_ENTRY_IS_BUSY(&entry->hdr));
    entry->flags &= ~flag;
    if (entry->flags)
        return;

    /*
     * Do a raw remove only if fewer entries were removed than would cause
     * alpha to be less than .5 (alpha is at most .75).  Otherwise, we just
     * call JS_DHashTableOperate to re-lookup the key and remove its entry,
     * compressing or shrinking the table as needed.
     */
    if (table->removedCount < JS_DHASH_TABLE_SIZE(table) >> 2)
        JS_DHashTableRawRemove(table, &entry->hdr);
    else
        JS_DHashTableOperate(table, key, JS_DHASH_REMOVE);
}

JSBool
js_EnterLocalRootScope(JSContext *cx)
{
    JSLocalRootStack *lrs;
    int mark;

    lrs = cx->localRootStack;
    if (!lrs) {
        lrs = (JSLocalRootStack *) JS_malloc(cx, sizeof *lrs);
        if (!lrs)
            return JS_FALSE;
        lrs->scopeMark = JSLRS_NULL_MARK;
        lrs->rootCount = 0;
        lrs->topChunk = &lrs->firstChunk;
        lrs->firstChunk.down = NULL;
        cx->localRootStack = lrs;
    }

    /* Push lrs->scopeMark to save it for restore when leaving. */
    mark = js_PushLocalRoot(cx, lrs, INT_TO_JSVAL(lrs->scopeMark));
    if (mark < 0)
        return JS_FALSE;
    lrs->scopeMark = (uint32) mark;
    return JS_TRUE;
}

void
js_LeaveLocalRootScopeWithResult(JSContext *cx, jsval rval)
{
    JSLocalRootStack *lrs;
    uint32 mark, m, n;
    JSLocalRootChunk *lrc;

    /* Defend against buggy native callers. */
    lrs = cx->localRootStack;
    JS_ASSERT(lrs && lrs->rootCount != 0);
    if (!lrs || lrs->rootCount == 0)
        return;

    mark = lrs->scopeMark;
    JS_ASSERT(mark != JSLRS_NULL_MARK);
    if (mark == JSLRS_NULL_MARK)
        return;

    /* Free any chunks being popped by this leave operation. */
    m = mark >> JSLRS_CHUNK_SHIFT;
    n = (lrs->rootCount - 1) >> JSLRS_CHUNK_SHIFT;
    while (n > m) {
        lrc = lrs->topChunk;
        JS_ASSERT(lrc != &lrs->firstChunk);
        lrs->topChunk = lrc->down;
        JS_free(cx, lrc);
        --n;
    }

    /*
     * Pop the scope, restoring lrs->scopeMark.  If rval is a GC-thing, push
     * it on the caller's scope, or store it in lastInternalResult if we are
     * leaving the outermost scope.  We don't need to allocate a new lrc
     * because we can overwrite the old mark's slot with rval.
     */
    lrc = lrs->topChunk;
    m = mark & JSLRS_CHUNK_MASK;
    lrs->scopeMark = (uint32) JSVAL_TO_INT(lrc->roots[m]);
    if (JSVAL_IS_GCTHING(rval) && !JSVAL_IS_NULL(rval)) {
        if (mark == 0) {
            cx->weakRoots.lastInternalResult = rval;
        } else {
            /*
             * Increment m to avoid the "else if (m == 0)" case below.  If
             * rval is not a GC-thing, that case would take care of freeing
             * any chunk that contained only the old mark.  Since rval *is*
             * a GC-thing here, we want to reuse that old mark's slot.
             */
            lrc->roots[m++] = rval;
            ++mark;
        }
    }
    lrs->rootCount = (uint32) mark;

    /*
     * Free the stack eagerly, risking malloc churn.  The alternative would
     * require an lrs->entryCount member, maintained by Enter and Leave, and
     * tested by the GC in addition to the cx->localRootStack non-null test.
     *
     * That approach would risk hoarding 264 bytes (net) per context.  Right
     * now it seems better to give fresh (dirty in CPU write-back cache, and
     * the data is no longer needed) memory back to the malloc heap.
     */
    if (mark == 0) {
        cx->localRootStack = NULL;
        JS_free(cx, lrs);
    } else if (m == 0) {
        lrs->topChunk = lrc->down;
        JS_free(cx, lrc);
    }
}

void
js_ForgetLocalRoot(JSContext *cx, jsval v)
{
    JSLocalRootStack *lrs;
    uint32 i, j, m, n, mark;
    JSLocalRootChunk *lrc, *lrc2;
    jsval top;

    lrs = cx->localRootStack;
    JS_ASSERT(lrs && lrs->rootCount);
    if (!lrs || lrs->rootCount == 0)
        return;

    /* Prepare to pop the top-most value from the stack. */
    n = lrs->rootCount - 1;
    m = n & JSLRS_CHUNK_MASK;
    lrc = lrs->topChunk;
    top = lrc->roots[m];

    /* Be paranoid about calls on an empty scope. */
    mark = lrs->scopeMark;
    JS_ASSERT(mark < n);
    if (mark >= n)
        return;

    /* If v was not the last root pushed in the top scope, find it. */
    if (top != v) {
        /* Search downward in case v was recently pushed. */
        i = n;
        j = m;
        lrc2 = lrc;
        while (--i > mark) {
            if (j == 0)
                lrc2 = lrc2->down;
            j = i & JSLRS_CHUNK_MASK;
            if (lrc2->roots[j] == v)
                break;
        }

        /* If we didn't find v in this scope, assert and bail out. */
        JS_ASSERT(i != mark);
        if (i == mark)
            return;

        /* Swap top and v so common tail code can pop v. */
        lrc2->roots[j] = top;
    }

    /* Pop the last value from the stack. */
    lrc->roots[m] = JSVAL_NULL;
    lrs->rootCount = n;
    if (m == 0) {
        JS_ASSERT(n != 0);
        JS_ASSERT(lrc != &lrs->firstChunk);
        lrs->topChunk = lrc->down;
        JS_free(cx, lrc);
    }
}

int
js_PushLocalRoot(JSContext *cx, JSLocalRootStack *lrs, jsval v)
{
    uint32 n, m;
    JSLocalRootChunk *lrc;

    n = lrs->rootCount;
    m = n & JSLRS_CHUNK_MASK;
    if (n == 0 || m != 0) {
        /*
         * At start of first chunk, or not at start of a non-first top chunk.
         * Check for lrs->rootCount overflow.
         */
        if ((uint32)(n + 1) == 0) {
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_TOO_MANY_LOCAL_ROOTS);
            return -1;
        }
        lrc = lrs->topChunk;
        JS_ASSERT(n != 0 || lrc == &lrs->firstChunk);
    } else {
        /*
         * After lrs->firstChunk, trying to index at a power-of-two chunk
         * boundary: need a new chunk.
         */
        lrc = (JSLocalRootChunk *) JS_malloc(cx, sizeof *lrc);
        if (!lrc)
            return -1;
        lrc->down = lrs->topChunk;
        lrs->topChunk = lrc;
    }
    lrs->rootCount = n + 1;
    lrc->roots[m] = v;
    return (int) n;
}

void
js_MarkLocalRoots(JSContext *cx, JSLocalRootStack *lrs)
{
    uint32 n, m, mark;
    JSLocalRootChunk *lrc;

    n = lrs->rootCount;
    if (n == 0)
        return;

    mark = lrs->scopeMark;
    lrc = lrs->topChunk;
    do {
        while (--n > mark) {
#ifdef GC_MARK_DEBUG
            char name[22];
            JS_snprintf(name, sizeof name, "<local root %u>", n);
#endif
            m = n & JSLRS_CHUNK_MASK;
            JS_ASSERT(JSVAL_IS_GCTHING(lrc->roots[m]));
            GC_MARK(cx, JSVAL_TO_GCTHING(lrc->roots[m]), name);
            if (m == 0)
                lrc = lrc->down;
        }
        m = n & JSLRS_CHUNK_MASK;
        mark = JSVAL_TO_INT(lrc->roots[m]);
        if (m == 0)
            lrc = lrc->down;
    } while (n != 0);
    JS_ASSERT(!lrc);
}

static void
ReportError(JSContext *cx, const char *message, JSErrorReport *reportp)