jscntxt.c

来自「一个基于alice开发的机器人」· C语言 代码 · 共 703 行 · 第 1/2 页

/* -*- 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 ***** */

/*
 * JS execution context.
 */
#include "jsstddef.h"
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsarena.h" /* Added by JSIFY */
#include "jsutil.h" /* Added by JSIFY */
#include "jsclist.h"
#include "jsprf.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsdbgapi.h"
#include "jsexn.h"
#include "jsgc.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsscan.h"
#include "jsscript.h"
#include "jsstr.h"

JSContext *
js_NewContext(JSRuntime *rt, size_t stackChunkSize)
{
    JSContext *cx;
    JSBool ok, first;

    cx = (JSContext *) malloc(sizeof *cx);
    if (!cx)
        return NULL;
    memset(cx, 0, sizeof *cx);

    cx->runtime = rt;
#if JS_STACK_GROWTH_DIRECTION > 0
    cx->stackLimit = (jsuword)-1;
#endif
#ifdef JS_THREADSAFE
    js_InitContextForLocking(cx);
#endif

    JS_LOCK_GC(rt);
    for (;;) {
        first = (rt->contextList.next == &rt->contextList);
        if (rt->state == JSRTS_UP) {
            JS_ASSERT(!first);
            break;
        }
        if (rt->state == JSRTS_DOWN) {
            JS_ASSERT(first);
            rt->state = JSRTS_LAUNCHING;
            break;
        }
        JS_WAIT_CONDVAR(rt->stateChange, JS_NO_TIMEOUT);
    }
    JS_APPEND_LINK(&cx->links, &rt->contextList);
    JS_UNLOCK_GC(rt);

    /*
     * First we do the infallible, every-time per-context initializations.
     * Should a later, fallible initialization (js_InitRegExpStatics, e.g.,
     * or the stuff under 'if (first)' below) fail, at least the version
     * and arena-pools will be valid and safe to use (say, from the last GC
     * done by js_DestroyContext).
     */
    cx->version = JSVERSION_DEFAULT;
    cx->jsop_eq = JSOP_EQ;
    cx->jsop_ne = JSOP_NE;
    JS_InitArenaPool(&cx->stackPool, "stack", stackChunkSize, sizeof(jsval));
    JS_InitArenaPool(&cx->tempPool, "temp", 1024, sizeof(jsdouble));

#if JS_HAS_REGEXPS
    if (!js_InitRegExpStatics(cx, &cx->regExpStatics)) {
        js_DestroyContext(cx, JS_NO_GC);
        return NULL;
    }
#endif
#if JS_HAS_EXCEPTIONS
    cx->throwing = JS_FALSE;
#endif

    /*
     * If cx is the first context on this runtime, initialize well-known atoms,
     * keywords, numbers, and strings.  If one of these steps should fail, the
     * runtime will be left in a partially initialized state, with zeroes and
     * nulls stored in the default-initialized remainder of the struct.  We'll
     * clean the runtime up under js_DestroyContext, because cx will be "last"
     * as well as "first".
     */
    if (first) {
        ok = (rt->atomState.liveAtoms == 0)
             ? js_InitAtomState(cx, &rt->atomState)
             : js_InitPinnedAtoms(cx, &rt->atomState);
        if (ok)
            ok = js_InitScanner(cx);
        if (ok)
            ok = js_InitRuntimeNumberState(cx);
        if (ok)
            ok = js_InitRuntimeStringState(cx);
        if (!ok) {
            js_DestroyContext(cx, JS_NO_GC);
            return NULL;
        }

        JS_LOCK_GC(rt);
        rt->state = JSRTS_UP;
        JS_NOTIFY_ALL_CONDVAR(rt->stateChange);
        JS_UNLOCK_GC(rt);
    }

    return cx;
}

void
js_DestroyContext(JSContext *cx, JSGCMode gcmode)
{
    JSRuntime *rt;
    JSBool last;
    JSArgumentFormatMap *map;

    rt = cx->runtime;

    /* Remove cx from context list first. */
    JS_LOCK_GC(rt);
    JS_ASSERT(rt->state == JSRTS_UP || rt->state == JSRTS_LAUNCHING);
    JS_REMOVE_LINK(&cx->links);
    last = (rt->contextList.next == &rt->contextList);
    if (last)
        rt->state = JSRTS_LANDING;
    JS_UNLOCK_GC(rt);

    if (last) {
#ifdef JS_THREADSAFE
        /*
         * If cx is not in a request already, begin one now so that we wait
         * for any racing GC started on a not-last context to finish, before
         * we plow ahead and unpin atoms.  Note that even though we begin a
         * request here if necessary, we end all requests on cx below before
         * forcing a final GC.  This lets any not-last context destruction
         * racing in another thread try to force or maybe run the GC, but by
         * that point, rt->state will not be JSRTS_UP, and that GC attempt
         * will return early.
         */
        if (cx->requestDepth == 0)
            JS_BeginRequest(cx);
#endif

        /* Unpin all pinned atoms before final GC. */
        js_UnpinPinnedAtoms(&rt->atomState);

        /* Unlock and clear GC things held by runtime pointers. */
        js_FinishRuntimeNumberState(cx);
        js_FinishRuntimeStringState(cx);

        /* Clear debugging state to remove GC roots. */
        JS_ClearAllTraps(cx);
        JS_ClearAllWatchPoints(cx);
    }

#if JS_HAS_REGEXPS
    /*
     * Remove more GC roots in regExpStatics, then collect garbage.
     * XXX anti-modularity alert: we rely on the call to js_RemoveRoot within
     * XXX this function call to wait for any racing GC to complete, in the
     * XXX case where JS_DestroyContext is called outside of a request on cx
     */
    js_FreeRegExpStatics(cx, &cx->regExpStatics);
#endif

#ifdef JS_THREADSAFE
    /*
     * Destroying a context implicitly calls JS_EndRequest().  Also, we must
     * end our request here in case we are "last" -- in that event, another
     * js_DestroyContext that was not last might be waiting in the GC for our
     * request to end.  We'll let it run below, just before we do the truly
     * final GC and then free atom state.
     *
     * At this point, cx must be inaccessible to other threads.  It's off the
     * rt->contextList, and it should not be reachable via any object private
     * data structure.
     */
    while (cx->requestDepth != 0)
        JS_EndRequest(cx);
#endif

    if (last) {
        /* Always force, so we wait for any racing GC to finish. */
        js_ForceGC(cx, GC_LAST_CONTEXT);

        /* Iterate until no finalizer removes a GC root or lock. */
        while (rt->gcPoke)
            js_GC(cx, GC_LAST_CONTEXT);

        /* Try to free atom state, now that no unrooted scripts survive. */
        if (rt->atomState.liveAtoms == 0)
            js_FreeAtomState(cx, &rt->atomState);

        /* Take the runtime down, now that it has no contexts or atoms. */
        JS_LOCK_GC(rt);
        rt->state = JSRTS_DOWN;
        JS_NOTIFY_ALL_CONDVAR(rt->stateChange);
        JS_UNLOCK_GC(rt);
    } else {
        if (gcmode == JS_FORCE_GC)
            js_ForceGC(cx, 0);
        else if (gcmode == JS_MAYBE_GC)
            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;
    }

    /* 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;
}

static void
ReportError(JSContext *cx, const char *message, JSErrorReport *reportp)
{
    /*
     * Check the error report, and set a JavaScript-catchable exception
     * if the error is defined to have an associated exception.  If an
     * exception is thrown, then the JSREPORT_EXCEPTION flag will be set
     * on the error report, and exception-aware hosts should ignore it.
     */
    if (reportp && reportp->errorNumber == JSMSG_UNCAUGHT_EXCEPTION)
        reportp->flags |= JSREPORT_EXCEPTION;

#if JS_HAS_ERROR_EXCEPTIONS
    /*
     * Call the error reporter only if an exception wasn't raised.
     *
     * If an exception was raised, then we call the debugErrorHook
     * (if present) to give it a chance to see the error before it
     * propagates out of scope.  This is needed for compatability
     * with the old scheme.
     */
    if (!js_ErrorToException(cx, message, reportp)) {
        js_ReportErrorAgain(cx, message, reportp);
    } else if (cx->runtime->debugErrorHook && cx->errorReporter) {
        JSDebugErrorHook hook = cx->runtime->debugErrorHook;
        /* test local in case debugErrorHook changed on another thread */
        if (hook)
            hook(cx, message, reportp, cx->runtime->debugErrorHookData);
    }
#else
    js_ReportErrorAgain(cx, message, reportp);
#endif
}

/*
 * We don't post an exception in this case, since doing so runs into
 * complications of pre-allocating an exception object which required
 * running the Exception class initializer early etc.
 * Instead we just invoke the errorReporter with an "Out Of Memory"
 * type message, and then hope the process ends swiftly.
 */
void
js_ReportOutOfMemory(JSContext *cx, JSErrorCallback callback)
{
    JSStackFrame *fp;