prefork.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

                    "caught SIGTERM, shutting down");

        return 1;
    } else if (shutdown_pending) {
        /* Time to perform a graceful shut down:
         * Reap the inactive children, and ask the active ones
         * to close their listeners, then wait until they are
         * all done to exit.
         */
        int active_children;
        apr_time_t cutoff = 0;

        /* Stop listening */
        ap_close_listeners();

        /* kill off the idle ones */
        ap_mpm_pod_killpg(pod, ap_max_daemons_limit);

        /* Send SIGUSR1 to the active children */
        active_children = 0;
        for (index = 0; index < ap_daemons_limit; ++index) {
            if (ap_scoreboard_image->servers[index][0].status != SERVER_DEAD) {
                /* Ask each child to close its listeners. */
                ap_mpm_safe_kill(MPM_CHILD_PID(index), AP_SIG_GRACEFUL);
                active_children++;
            }
        }

        /* Allow each child which actually finished to exit */
        ap_relieve_child_processes();

        /* cleanup pid file */
        {
            const char *pidfile = NULL;
            pidfile = ap_server_root_relative (pconf, ap_pid_fname);
            if ( pidfile != NULL && unlink(pidfile) == 0)
                ap_log_error(APLOG_MARK, APLOG_INFO,
                                0, ap_server_conf,
                                "removed PID file %s (pid=%ld)",
                                pidfile, (long)getpid());
        }

        ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
           "caught " AP_SIG_GRACEFUL_STOP_STRING ", shutting down gracefully");

        if (ap_graceful_shutdown_timeout) {
            cutoff = apr_time_now() +
                     apr_time_from_sec(ap_graceful_shutdown_timeout);
        }

        /* Don't really exit until each child has finished */
        shutdown_pending = 0;
        do {
            /* Pause for a second */
            sleep(1);

            /* Relieve any children which have now exited */
            ap_relieve_child_processes();

            active_children = 0;
            for (index = 0; index < ap_daemons_limit; ++index) {
                if (ap_mpm_safe_kill(MPM_CHILD_PID(index), 0) == APR_SUCCESS) {
                    active_children = 1;
                    /* Having just one child is enough to stay around */
                    break;
                }
            }
        } while (!shutdown_pending && active_children &&
                 (!ap_graceful_shutdown_timeout || apr_time_now() < cutoff));

        /* We might be here because we received SIGTERM, either
         * way, try and make sure that all of our processes are
         * really dead.
         */
        unixd_killpg(getpgrp(), SIGTERM);

        return 1;
    }

    /* we've been told to restart */
    apr_signal(SIGHUP, SIG_IGN);
    apr_signal(AP_SIG_GRACEFUL, SIG_IGN);
    if (one_process) {
        /* not worth thinking about */
        return 1;
    }

    /* advance to the next generation */
    /* XXX: we really need to make sure this new generation number isn't in
     * use by any of the children.
     */
    ++ap_my_generation;
    ap_scoreboard_image->global->running_generation = ap_my_generation;

    if (is_graceful) {
        ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
                    "Graceful restart requested, doing restart");

        /* kill off the idle ones */
        ap_mpm_pod_killpg(pod, ap_max_daemons_limit);

        /* This is mostly for debugging... so that we know what is still
         * gracefully dealing with existing request.  This will break
         * in a very nasty way if we ever have the scoreboard totally
         * file-based (no shared memory)
         */
        for (index = 0; index < ap_daemons_limit; ++index) {
            if (ap_scoreboard_image->servers[index][0].status != SERVER_DEAD) {
                ap_scoreboard_image->servers[index][0].status = SERVER_GRACEFUL;
                /* Ask each child to close its listeners.
                 *
                 * NOTE: we use the scoreboard, because if we send SIGUSR1
                 * to every process in the group, this may include CGI's,
                 * piped loggers, etc. They almost certainly won't handle
                 * it gracefully.
                 */
                ap_mpm_safe_kill(ap_scoreboard_image->parent[index].pid, AP_SIG_GRACEFUL);
            }
        }
    }
    else {
        /* Kill 'em off */
        if (unixd_killpg(getpgrp(), SIGHUP) < 0) {
            ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "killpg SIGHUP");
        }
        ap_reclaim_child_processes(0);          /* Not when just starting up */
        ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
                    "SIGHUP received.  Attempting to restart");
    }

    return 0;
}

/* This really should be a post_config hook, but the error log is already
 * redirected by that point, so we need to do this in the open_logs phase.
 */
static int prefork_open_logs(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s)
{
    apr_status_t rv;

    pconf = p;
    ap_server_conf = s;

    if ((num_listensocks = ap_setup_listeners(ap_server_conf)) < 1) {
        ap_log_error(APLOG_MARK, APLOG_ALERT|APLOG_STARTUP, 0,
                     NULL, "no listening sockets available, shutting down");
        return DONE;
    }

    if ((rv = ap_mpm_pod_open(pconf, &pod))) {
        ap_log_error(APLOG_MARK, APLOG_CRIT|APLOG_STARTUP, rv, NULL,
                "Could not open pipe-of-death.");
        return DONE;
    }
    return OK;
}

static int prefork_pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp)
{
    static int restart_num = 0;
    int no_detach, debug, foreground;
    apr_status_t rv;

    mpm_state = AP_MPMQ_STARTING;

    debug = ap_exists_config_define("DEBUG");

    if (debug) {
        foreground = one_process = 1;
        no_detach = 0;
    }
    else
    {
        no_detach = ap_exists_config_define("NO_DETACH");
        one_process = ap_exists_config_define("ONE_PROCESS");
        foreground = ap_exists_config_define("FOREGROUND");
    }

    /* sigh, want this only the second time around */
    if (restart_num++ == 1) {
        is_graceful = 0;

        if (!one_process && !foreground) {
            rv = apr_proc_detach(no_detach ? APR_PROC_DETACH_FOREGROUND
                                           : APR_PROC_DETACH_DAEMONIZE);
            if (rv != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_CRIT, rv, NULL,
                             "apr_proc_detach failed");
                return HTTP_INTERNAL_SERVER_ERROR;
            }
        }

        parent_pid = ap_my_pid = getpid();
    }

    unixd_pre_config(ptemp);
    ap_listen_pre_config();
    ap_daemons_to_start = DEFAULT_START_DAEMON;
    ap_daemons_min_free = DEFAULT_MIN_FREE_DAEMON;
    ap_daemons_max_free = DEFAULT_MAX_FREE_DAEMON;
    ap_daemons_limit = server_limit;
    ap_pid_fname = DEFAULT_PIDLOG;
    ap_lock_fname = DEFAULT_LOCKFILE;
    ap_max_requests_per_child = DEFAULT_MAX_REQUESTS_PER_CHILD;
    ap_extended_status = 0;
#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
    ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;
#endif

    apr_cpystrn(ap_coredump_dir, ap_server_root, sizeof(ap_coredump_dir));

    return OK;
}

static void prefork_hooks(apr_pool_t *p)
{
    /* The prefork open_logs phase must run before the core's, or stderr
     * will be redirected to a file, and the messages won't print to the
     * console.
     */
    static const char *const aszSucc[] = {"core.c", NULL};

#ifdef AUX3
    (void) set42sig();
#endif

    ap_hook_open_logs(prefork_open_logs, NULL, aszSucc, APR_HOOK_MIDDLE);
    /* we need to set the MPM state before other pre-config hooks use MPM query
     * to retrieve it, so register as REALLY_FIRST
     */
    ap_hook_pre_config(prefork_pre_config, NULL, NULL, APR_HOOK_REALLY_FIRST);
}

static const char *set_daemons_to_start(cmd_parms *cmd, void *dummy, const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_daemons_to_start = atoi(arg);
    return NULL;
}

static const char *set_min_free_servers(cmd_parms *cmd, void *dummy, const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_daemons_min_free = atoi(arg);
    if (ap_daemons_min_free <= 0) {
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    "WARNING: detected MinSpareServers set to non-positive.");
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    "Resetting to 1 to avoid almost certain Apache failure.");
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    "Please read the documentation.");
       ap_daemons_min_free = 1;
    }

    return NULL;
}

static const char *set_max_free_servers(cmd_parms *cmd, void *dummy, const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_daemons_max_free = atoi(arg);
    return NULL;
}

static const char *set_max_clients (cmd_parms *cmd, void *dummy, const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_daemons_limit = atoi(arg);
    if (ap_daemons_limit > server_limit) {
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    "WARNING: MaxClients of %d exceeds ServerLimit value "
                    "of %d servers,", ap_daemons_limit, server_limit);
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    " lowering MaxClients to %d.  To increase, please "
                    "see the ServerLimit", server_limit);
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    " directive.");
       ap_daemons_limit = server_limit;
    }
    else if (ap_daemons_limit < 1) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                     "WARNING: Require MaxClients > 0, setting to 1");
        ap_daemons_limit = 1;
    }
    return NULL;
}

static const char *set_server_limit (cmd_parms *cmd, void *dummy, const char *arg)
{
    int tmp_server_limit;

    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    tmp_server_limit = atoi(arg);
    /* you cannot change ServerLimit across a restart; ignore
     * any such attempts
     */
    if (first_server_limit &&
        tmp_server_limit != server_limit) {
        /* how do we log a message?  the error log is a bit bucket at this
         * point; we'll just have to set a flag so that ap_mpm_run()
         * logs a warning later
         */
        changed_limit_at_restart = 1;
        return NULL;
    }
    server_limit = tmp_server_limit;

    if (server_limit > MAX_SERVER_LIMIT) {
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    "WARNING: ServerLimit of %d exceeds compile time limit "
                    "of %d servers,", server_limit, MAX_SERVER_LIMIT);
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                    " lowering ServerLimit to %d.", MAX_SERVER_LIMIT);
       server_limit = MAX_SERVER_LIMIT;
    }
    else if (server_limit < 1) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                     "WARNING: Require ServerLimit > 0, setting to 1");
        server_limit = 1;
    }
    return NULL;
}

static const command_rec prefork_cmds[] = {
UNIX_DAEMON_COMMANDS,
LISTEN_COMMANDS,
AP_INIT_TAKE1("StartServers", set_daemons_to_start, NULL, RSRC_CONF,
              "Number of child processes launched at server startup"),
AP_INIT_TAKE1("MinSpareServers", set_min_free_servers, NULL, RSRC_CONF,
              "Minimum number of idle children, to handle request spikes"),
AP_INIT_TAKE1("MaxSpareServers", set_max_free_servers, NULL, RSRC_CONF,
              "Maximum number of idle children"),
AP_INIT_TAKE1("MaxClients", set_max_clients, NULL, RSRC_CONF,
              "Maximum number of children alive at the same time"),
AP_INIT_TAKE1("ServerLimit", set_server_limit, NULL, RSRC_CONF,
              "Maximum value of MaxClients for this run of Apache"),
AP_GRACEFUL_SHUTDOWN_TIMEOUT_COMMAND,
{ NULL }
};

module AP_MODULE_DECLARE_DATA mpm_prefork_module = {
    MPM20_MODULE_STUFF,
    ap_mpm_rewrite_args,        /* hook to run before apache parses args */
    NULL,                       /* create per-directory config structure */
    NULL,                       /* merge per-directory config structures */
    NULL,                       /* create per-server config structure */
    NULL,                       /* merge per-server config structures */
    prefork_cmds,               /* command apr_table_t */
    prefork_hooks,              /* register hooks */
};