mpmt_os2.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

        PID child_pid;
        int active_children = 0;

        /* Count number of active children */
        for (slot=0; slot < HARD_SERVER_LIMIT; slot++) {
            active_children += ap_scoreboard_image->parent[slot].pid != 0 &&
                !ap_scoreboard_image->parent[slot].quiescing;
        }

        /* Spawn children if needed */
        for (slot=0; slot < HARD_SERVER_LIMIT && active_children < ap_daemons_to_start; slot++) {
            if (ap_scoreboard_image->parent[slot].pid == 0) {
                spawn_child(slot);
                active_children++;
            }
        }

        rc = DosWaitChild(DCWA_PROCESSTREE, DCWW_NOWAIT, &proc_rc, &child_pid, 0);

        if (rc == 0) {
            /* A child has terminated, remove its scoreboard entry & terminate if necessary */
            for (slot=0; ap_scoreboard_image->parent[slot].pid != child_pid && slot < HARD_SERVER_LIMIT; slot++);

            if (slot < HARD_SERVER_LIMIT) {
                ap_scoreboard_image->parent[slot].pid = 0;
                ap_scoreboard_image->parent[slot].quiescing = 0;

                if (proc_rc.codeTerminate == TC_EXIT) {
                    /* Child terminated normally, check its exit code and
                     * terminate server if child indicates a fatal error
                     */
                    if (proc_rc.codeResult == APEXIT_CHILDFATAL)
                        break;
                }
            }
        } else if (rc == ERROR_CHILD_NOT_COMPLETE) {
            /* No child exited, lets sleep for a while.... */
            apr_sleep(SCOREBOARD_MAINTENANCE_INTERVAL);
        }
    }

    /* Signal children to shut down, either gracefully or immediately */
    for (slot=0; slot<HARD_SERVER_LIMIT; slot++) {
      kill(ap_scoreboard_image->parent[slot].pid, is_graceful ? SIGHUP : SIGTERM);
    }

    DosFreeMem(parent_info);
    return restart_pending;
}



static void spawn_child(int slot)
{
    PPIB ppib;
    PTIB ptib;
    char fail_module[100];
    char progname[CCHMAXPATH];
    RESULTCODES proc_rc;
    ULONG rc;

    ap_scoreboard_image->parent[slot].generation = ap_my_generation;
    DosGetInfoBlocks(&ptib, &ppib);
    DosQueryModuleName(ppib->pib_hmte, sizeof(progname), progname);
    rc = DosExecPgm(fail_module, sizeof(fail_module), EXEC_ASYNCRESULT,
                    ppib->pib_pchcmd, NULL, &proc_rc, progname);

    if (rc) {
        ap_log_error(APLOG_MARK, APLOG_ERR, APR_FROM_OS_ERROR(rc), ap_server_conf,
                     "error spawning child, slot %d", slot);
    }

    if (ap_max_daemons_limit < slot) {
        ap_max_daemons_limit = slot;
    }

    ap_scoreboard_image->parent[slot].pid = proc_rc.codeTerminate;
}



/* Signal handling routines */

static void sig_term(int sig)
{
    shutdown_pending = 1;
    signal(SIGTERM, SIG_DFL);
}



static void sig_restart(int sig)
{
    if (sig == SIGUSR1) {
        is_graceful = 1;
    }

    restart_pending = 1;
}



static void set_signals()
{
    struct sigaction sa;

    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_handler = sig_term;

    if (sigaction(SIGTERM, &sa, NULL) < 0)
	ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGTERM)");

    if (sigaction(SIGINT, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGINT)");

    sa.sa_handler = sig_restart;

    if (sigaction(SIGHUP, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGHUP)");
    if (sigaction(SIGUSR1, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGUSR1)");
}



/* Enquiry functions used get MPM status info */

AP_DECLARE(apr_status_t) ap_mpm_query(int query_code, int *result)
{
    switch (query_code) {
        case AP_MPMQ_MAX_DAEMON_USED:
            *result = ap_max_daemons_limit;
            return APR_SUCCESS;
        case AP_MPMQ_IS_THREADED:
            *result = AP_MPMQ_DYNAMIC;
            return APR_SUCCESS;
        case AP_MPMQ_IS_FORKED:
            *result = AP_MPMQ_NOT_SUPPORTED;
            return APR_SUCCESS;
        case AP_MPMQ_HARD_LIMIT_DAEMONS:
            *result = HARD_SERVER_LIMIT;
            return APR_SUCCESS;
        case AP_MPMQ_HARD_LIMIT_THREADS:
            *result = HARD_THREAD_LIMIT;
            return APR_SUCCESS;
        case AP_MPMQ_MIN_SPARE_DAEMONS:
            *result = 0;
            return APR_SUCCESS;
        case AP_MPMQ_MAX_SPARE_DAEMONS:
            *result = 0;
            return APR_SUCCESS;
        case AP_MPMQ_MAX_REQUESTS_DAEMON:
            *result = ap_max_requests_per_child;
            return APR_SUCCESS; 
    }
    return APR_ENOTIMPL;
} 



int ap_graceful_stop_signalled(void)
{
    return is_graceful;
}



/* Configuration handling stuff */

static int mpmt_os2_pre_config(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp)
{
    one_process = ap_exists_config_define("ONE_PROCESS") || 
                  ap_exists_config_define("DEBUG");
    is_graceful = 0;
    ap_listen_pre_config();
    ap_daemons_to_start = DEFAULT_START_DAEMON;
    ap_thread_limit = HARD_THREAD_LIMIT;
    ap_pid_fname = DEFAULT_PIDLOG;
    ap_max_requests_per_child = DEFAULT_MAX_REQUESTS_PER_CHILD;
    ap_extended_status = 0;
    ap_min_spare_threads = DEFAULT_MIN_SPARE_THREAD;
    ap_max_spare_threads = DEFAULT_MAX_SPARE_THREAD;
#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
	ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;
#endif

    return OK;
}



static void mpmt_os2_hooks(apr_pool_t *p)
{
    ap_hook_pre_config(mpmt_os2_pre_config, NULL, NULL, APR_HOOK_MIDDLE);
}



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_spare_threads(cmd_parms *cmd, void *dummy,
					 const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);

    if (err != NULL) {
        return err;
    }

    ap_min_spare_threads = atoi(arg);

    if (ap_min_spare_threads <= 0) {
       ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, 
                    "WARNING: detected MinSpareThreads 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_min_spare_threads = 1;
    }
       
    return NULL;
}



static const char *set_max_spare_threads(cmd_parms *cmd, void *dummy,
					 const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);

    if (err != NULL) {
        return err;
    }

    ap_max_spare_threads = atoi(arg);
    return NULL;
}



static const char *ignore_cmd(cmd_parms *cmd, void *dummy, const char *arg)
{
    return NULL;
}



static const command_rec mpmt_os2_cmds[] = {
LISTEN_COMMANDS,
AP_INIT_TAKE1( "StartServers", set_daemons_to_start, NULL, RSRC_CONF, 
  "Number of child processes launched at server startup" ),
AP_INIT_TAKE1("MinSpareThreads", set_min_spare_threads, NULL, RSRC_CONF,
  "Minimum number of idle children, to handle request spikes"),
AP_INIT_TAKE1("MaxSpareThreads", set_max_spare_threads, NULL, RSRC_CONF,
  "Maximum number of idle children"),
AP_INIT_TAKE1("User", ignore_cmd, NULL, RSRC_CONF,
  "Not applicable on this platform"),
AP_INIT_TAKE1("Group", ignore_cmd, NULL, RSRC_CONF,
  "Not applicable on this platform"),
AP_INIT_TAKE1("ScoreBoardFile", ignore_cmd, NULL, RSRC_CONF, \
  "Not applicable on this platform"),
{ NULL }
};

module AP_MODULE_DECLARE_DATA mpm_mpmt_os2_module = {
    MPM20_MODULE_STUFF,
    NULL,                       /* 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 */
    mpmt_os2_cmds,		/* command apr_table_t */
    mpmt_os2_hooks,		/* register_hooks */
};