perchild.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

#ifdef SIGXCPU
    sa.sa_handler = SIG_DFL;
    if (sigaction(SIGXCPU, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(SIGXCPU)");
#endif
#ifdef SIGXFSZ
    sa.sa_handler = SIG_DFL;
    if (sigaction(SIGXFSZ, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(SIGXFSZ)");
#endif
#ifdef SIGPIPE
    sa.sa_handler = SIG_IGN;
    if (sigaction(SIGPIPE, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(SIGPIPE)");
#endif

    /* we want to ignore HUPs and AP_SIG_GRACEFUL while we're busy 
     * processing one */
    sigaddset(&sa.sa_mask, SIGHUP);
    sigaddset(&sa.sa_mask, AP_SIG_GRACEFUL);
    sa.sa_handler = restart;
    if (sigaction(SIGHUP, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(SIGHUP)");
    if (sigaction(AP_SIG_GRACEFUL, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(" AP_SIG_GRACEFUL_STRING ")");
#else
    if (!one_process) {
#ifdef SIGXCPU
        apr_signal(SIGXCPU, SIG_DFL);
#endif /* SIGXCPU */
#ifdef SIGXFSZ
        apr_signal(SIGXFSZ, SIG_DFL);
#endif /* SIGXFSZ */
    }

    apr_signal(SIGTERM, sig_term);
#ifdef SIGHUP
    apr_signal(SIGHUP, restart);
#endif /* SIGHUP */
#ifdef AP_SIG_GRACEFUL
    apr_signal(AP_SIG_GRACEFUL, restart);
#endif /* AP_SIG_GRACEFUL */
#ifdef SIGPIPE
    apr_signal(SIGPIPE, SIG_IGN);
#endif /* SIGPIPE */

#endif
}

/*****************************************************************
 * Here follows a long bunch of generic server bookkeeping stuff...
 */

int ap_graceful_stop_signalled(void)
{
    /* XXX - Does this really work? - Manoj */
    return is_graceful;
}

/*****************************************************************
 * Child process main loop.
 */

static void process_socket(apr_pool_t *p, apr_socket_t *sock, long conn_id,
                           apr_bucket_alloc_t *bucket_alloc)
{
    conn_rec *current_conn;
    int csd;
    apr_status_t rv;
    int thread_num = conn_id % thread_limit;
    ap_sb_handle_t *sbh;

    if ((rv = apr_os_sock_get(&csd, sock)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, NULL, "apr_os_sock_get");
    }

    if (thread_socket_table[thread_num] < 0) {
        ap_sock_disable_nagle(sock);
    }

    ap_create_sb_handle(&sbh, p, conn_id / thread_limit, thread_num);
    current_conn = ap_run_create_connection(p, ap_server_conf, sock, conn_id, 
                                            sbh, bucket_alloc);
    if (current_conn) {
        ap_process_connection(current_conn, sock);
        ap_lingering_close(current_conn);
    }
}

static int perchild_process_connection(conn_rec *c)
{
    ap_filter_t *f;
    apr_bucket_brigade *bb;
    core_net_rec *net;

    apr_pool_userdata_get((void **)&bb, "PERCHILD_SOCKETS", c->pool);
    if (bb != NULL) {
        for (f = c->output_filters; f != NULL; f = f->next) {
            if (!strcmp(f->frec->name, "core")) {
                break;
            }
        }
        if (f != NULL) {
            net = f->ctx;
            net->in_ctx = apr_palloc(c->pool, sizeof(*net->in_ctx));
            net->in_ctx->b = bb;
        }
    }
    return DECLINED;
}
    

static void *worker_thread(apr_thread_t *, void *);

/* Starts a thread as long as we're below max_threads */
static int start_thread(void)
{
    apr_thread_t *thread;
    int rc;

    apr_thread_mutex_lock(worker_thread_count_mutex);
    if (worker_thread_count < max_threads - 1) {
        rc = apr_thread_create(&thread, worker_thread_attr, worker_thread,
                 &worker_thread_free_ids[worker_thread_count], pchild);
        if (rc != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_ALERT, rc, ap_server_conf,
                         "apr_thread_create: unable to create worker thread");
            /* In case system resources are maxxed out, we don't want
               Apache running away with the CPU trying to fork over and
               over and over again if we exit. */
            sleep(10);
            workers_may_exit = 1;
            apr_thread_mutex_unlock(worker_thread_count_mutex);
            return 0;
        }
        else {
            worker_thread_count++;
        }
    }
    else {
        static int reported = 0;
        
        if (!reported) {
            ap_log_error(APLOG_MARK, APLOG_ERR, 0,
                         ap_server_conf,
                         "server reached MaxThreadsPerChild setting, "
                         "consider raising the MaxThreadsPerChild or "
                         "NumServers settings");
            reported = 1;
        }
        apr_thread_mutex_unlock(worker_thread_count_mutex);
        return 0;
    }
    apr_thread_mutex_unlock(worker_thread_count_mutex);
    return 1;

}

/* Sets workers_may_exit if we received a character on the pipe_of_death */
static apr_status_t check_pipe_of_death(void **csd, ap_listen_rec *lr,
                                        apr_pool_t *ptrans)
{
    apr_thread_mutex_lock(pipe_of_death_mutex);
    if (!workers_may_exit) {
        int ret;
        char pipe_read_char;
        apr_size_t n = 1;

        ret = apr_recv(lr->sd, &pipe_read_char, &n);
        if (APR_STATUS_IS_EAGAIN(ret)) {
            /* It lost the lottery. It must continue to suffer
             * through a life of servitude. */
        }
        else {
            /* It won the lottery (or something else is very
             * wrong). Embrace death with open arms. */
            workers_may_exit = 1;
        }
    }
    apr_thread_mutex_unlock(pipe_of_death_mutex);
    return APR_SUCCESS;
}

static apr_status_t receive_from_other_child(void **csd, ap_listen_rec *lr,
                                             apr_pool_t *ptrans)
{
    struct msghdr msg;
    struct cmsghdr *cmsg;
    char buffer[HUGE_STRING_LEN * 2], *headers, *body;
    int headerslen, bodylen;
    struct iovec iov;
    int ret, dp;
    apr_os_sock_t sd;
    apr_bucket_alloc_t *alloc = apr_bucket_alloc_create(ptrans);
    apr_bucket_brigade *bb = apr_brigade_create(ptrans, alloc);
    apr_bucket *bucket;

    apr_os_sock_get(&sd, lr->sd);

    iov.iov_base = buffer;
    iov.iov_len = sizeof(buffer);

    msg.msg_name = NULL;
    msg.msg_namelen = 0;
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;

    cmsg = apr_palloc(ptrans, sizeof(*cmsg) + sizeof(sd));
    cmsg->cmsg_len = sizeof(*cmsg) + sizeof(sd);
    msg.msg_control = cmsg;
    msg.msg_controllen = cmsg->cmsg_len;

    ret = recvmsg(sd, &msg, 0);

    memcpy(&dp, CMSG_DATA(cmsg), sizeof(dp));

    *csd = NULL; /* tell apr_os_sock_put() to allocate new apr_socket_t */
    apr_os_sock_put((apr_socket_t **)csd, &dp, ptrans);

    bucket = apr_bucket_eos_create(alloc);
    APR_BRIGADE_INSERT_HEAD(bb, bucket);
    bucket = apr_bucket_socket_create(*csd, alloc);
    APR_BRIGADE_INSERT_HEAD(bb, bucket);

    body = strchr(iov.iov_base, 0);
    if (!body) {
        return 1;
    }

    body++;
    bodylen = strlen(body);

    headers = iov.iov_base;
    headerslen = body - headers;

    bucket = apr_bucket_heap_create(body, bodylen, NULL, alloc);
    APR_BRIGADE_INSERT_HEAD(bb, bucket);
    bucket = apr_bucket_heap_create(headers, headerslen, NULL, alloc);
    APR_BRIGADE_INSERT_HEAD(bb, bucket);

    apr_pool_userdata_set(bb, "PERCHILD_SOCKETS", NULL, ptrans);

    return 0;
}

/* idle_thread_count should be incremented before starting a worker_thread */

static void *worker_thread(apr_thread_t *thd, void *arg)
{
    void *csd;
    apr_pool_t *tpool;      /* Pool for this thread           */
    apr_pool_t *ptrans;     /* Pool for per-transaction stuff */
    volatile int thread_just_started = 1;
    int srv;
    int thread_num = *((int *) arg);
    long conn_id = child_num * thread_limit + thread_num;
    apr_pollfd_t *pollset;
    apr_status_t rv;
    ap_listen_rec *lr, *last_lr = ap_listeners;
    int n;
    apr_bucket_alloc_t *bucket_alloc;

    apr_thread_mutex_lock(thread_pool_parent_mutex);
    apr_pool_create(&tpool, thread_pool_parent);
    apr_thread_mutex_unlock(thread_pool_parent_mutex);
    apr_pool_create(&ptrans, tpool);

    (void) ap_update_child_status_from_indexes(child_num, thread_num, 
                                               SERVER_STARTING,
                                               (request_rec *) NULL);

    bucket_alloc = apr_bucket_alloc_create(apr_thread_pool_get(thd));

    apr_poll_setup(&pollset, num_listensocks, tpool);
    for(lr = ap_listeners; lr != NULL; lr = lr->next) {
        int fd;
        apr_poll_socket_add(pollset, lr->sd, APR_POLLIN);

        apr_os_sock_get(&fd, lr->sd);
    }

    while (!workers_may_exit) {
        workers_may_exit |= ((ap_max_requests_per_child != 0)
                            && (requests_this_child <= 0));
        if (workers_may_exit) break;
        if (!thread_just_started) {
            apr_thread_mutex_lock(idle_thread_count_mutex);
            if (idle_thread_count < max_spare_threads) {
                idle_thread_count++;
                apr_thread_mutex_unlock(idle_thread_count_mutex);
            }
            else {
                apr_thread_mutex_unlock(idle_thread_count_mutex);
                break;
            }
        }
        else {
            thread_just_started = 0;
        }

        (void) ap_update_child_status_from_indexes(child_num, thread_num, 
                                                   SERVER_READY,
                                                   (request_rec *) NULL);

        apr_thread_mutex_lock(thread_accept_mutex);
        if (workers_may_exit) {
            apr_thread_mutex_unlock(thread_accept_mutex);
            break;
        }
        if ((rv = SAFE_ACCEPT(apr_proc_mutex_lock(process_accept_mutex)))
            != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, rv, ap_server_conf,
                         "apr_proc_mutex_lock failed. Attempting to shutdown "
                         "process gracefully.");
            workers_may_exit = 1;
        }

        while (!workers_may_exit) {
            apr_int16_t event;
            srv = apr_poll(pollset, num_listensocks, &n, -1);

            if (srv != APR_SUCCESS) {
                if (APR_STATUS_IS_EINTR(srv)) {
                    continue;
                }

                /* apr_poll() will only return errors in catastrophic
                 * circumstances. Let's try exiting gracefully, for now. */
                ap_log_error(APLOG_MARK, APLOG_ERR, srv, (const server_rec *)
                             ap_server_conf, "apr_poll: (listen)");
                workers_may_exit = 1;
            }
            if (workers_may_exit) break;

            /* find a listener */
            lr = last_lr;
            do {
                lr = lr->next;
                if (lr == NULL) {
                    lr = ap_listeners;
                }
                /* XXX: Should we check for POLLERR? */
                apr_poll_revents_get(&event, lr->sd, pollset);
                if (event & (APR_POLLIN)) {
                    last_lr = lr;
                    goto got_fd;
                }
            } while (lr != last_lr);
        }
    got_fd:
        if (!workers_may_exit) {
            rv = lr->accept_func(&csd, lr, ptrans);
            if (rv == APR_EGENERAL) {
                /* E[NM]FILE, ENOMEM, etc */
                workers_may_exit = 1;
            }
            if ((rv = SAFE_ACCEPT(apr_proc_mutex_unlock(process_accept_mutex)))
                != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, ap_server_conf,
                             "apr_proc_mutex_unlock failed. Attempting to shutdown "
                             "process gracefully.");
                workers_may_exit = 1;
            }
            apr_thread_mutex_unlock(thread_accept_mutex);
            apr_thread_mutex_lock(idle_thread_count_mutex);
            if (idle_thread_count > min_spare_threads) {
                idle_thread_count--;
            }
            else {
                if (!start_thread()) {
                    idle_thread_count--;
                }
            }
            apr_thread_mutex_unlock(idle_thread_count_mutex);
            if (setjmp(jmpbuffer) != 1) {
                process_socket(ptrans, csd, conn_id, bucket_alloc);
            }