xref: /unit/src/nxt_router.c (revision 426)

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Valentin V. Bartenev
 * Copyright (C) NGINX, Inc.
 */

#include <nxt_router.h>
#include <nxt_conf.h>


typedef struct {
    nxt_str_t         type;
    uint32_t          workers;
    nxt_msec_t        timeout;
    uint32_t          requests;
    nxt_conf_value_t  *limits_value;
} nxt_router_app_conf_t;


typedef struct {
    nxt_str_t  application;
} nxt_router_listener_conf_t;


typedef struct nxt_msg_info_s {
    nxt_buf_t                 *buf;
    nxt_port_mmap_tracking_t  tracking;
    nxt_work_handler_t        completion_handler;
} nxt_msg_info_t;


typedef struct nxt_req_app_link_s nxt_req_app_link_t;


typedef struct {
    uint32_t             stream;
    nxt_conn_t           *conn;
    nxt_app_t            *app;
    nxt_port_t           *app_port;
    nxt_app_parse_ctx_t  *ap;
    nxt_msg_info_t       msg_info;
    nxt_req_app_link_t   *ra;

    nxt_queue_link_t     link;     /* for nxt_conn_t.requests */
} nxt_req_conn_link_t;


struct nxt_req_app_link_s {
    uint32_t             stream;
    nxt_atomic_t         use_count;
    nxt_port_t           *app_port;
    nxt_port_t           *reply_port;
    nxt_app_parse_ctx_t  *ap;
    nxt_msg_info_t       msg_info;
    nxt_req_conn_link_t  *rc;

    nxt_queue_link_t     link_app_requests; /* for nxt_app_t.requests */
    nxt_queue_link_t     link_port_pending; /* for nxt_port_t.pending_requests */

    nxt_mp_t             *mem_pool;
    nxt_work_t           work;

    int                  err_code;
    const char           *err_str;
};


typedef struct {
    nxt_socket_conf_t       *socket_conf;
    nxt_router_temp_conf_t  *temp_conf;
} nxt_socket_rpc_t;


static nxt_int_t nxt_router_start_worker(nxt_task_t *task, nxt_app_t *app);

nxt_inline void
nxt_router_ra_inc_use(nxt_req_app_link_t *ra)
{
    nxt_atomic_fetch_add(&ra->use_count, 1);
}

nxt_inline void
nxt_router_ra_dec_use(nxt_req_app_link_t *ra)
{
    int  c;

    c = nxt_atomic_fetch_add(&ra->use_count, -1);

    nxt_assert(c > 1);
}

static void nxt_router_ra_use(nxt_task_t *task, nxt_req_app_link_t *ra, int i);

static nxt_router_temp_conf_t *nxt_router_temp_conf(nxt_task_t *task);
static void nxt_router_conf_apply(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conf_ready(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf);
static void nxt_router_conf_error(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf);
static void nxt_router_conf_send(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf, nxt_port_msg_type_t type);

static nxt_int_t nxt_router_conf_create(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf, u_char *start, u_char *end);
static nxt_app_t *nxt_router_app_find(nxt_queue_t *queue, nxt_str_t *name);
static nxt_app_t *nxt_router_listener_application(nxt_router_temp_conf_t *tmcf,
    nxt_str_t *name);
static void nxt_router_listen_socket_rpc_create(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf, nxt_socket_conf_t *skcf);
static void nxt_router_listen_socket_ready(nxt_task_t *task,
    nxt_port_recv_msg_t *msg, void *data);
static void nxt_router_listen_socket_error(nxt_task_t *task,
    nxt_port_recv_msg_t *msg, void *data);
static nxt_socket_conf_t *nxt_router_socket_conf(nxt_task_t *task,
    nxt_router_temp_conf_t *tmcf, nxt_str_t *name);
static nxt_int_t nxt_router_listen_socket_find(nxt_router_temp_conf_t *tmcf,
    nxt_socket_conf_t *nskcf, nxt_sockaddr_t *sa);

static nxt_int_t nxt_router_engines_create(nxt_task_t *task,
    nxt_router_t *router, nxt_router_temp_conf_t *tmcf,
    const nxt_event_interface_t *interface);
static nxt_int_t nxt_router_engine_conf_create(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf);
static nxt_int_t nxt_router_engine_conf_update(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf);
static nxt_int_t nxt_router_engine_conf_delete(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf);
static nxt_int_t nxt_router_engine_joints_create(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf, nxt_queue_t *sockets,
    nxt_work_handler_t handler);
static nxt_int_t nxt_router_engine_quit(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf);
static nxt_int_t nxt_router_engine_joints_delete(nxt_router_temp_conf_t *tmcf,
    nxt_router_engine_conf_t *recf, nxt_queue_t *sockets);

static nxt_int_t nxt_router_threads_create(nxt_task_t *task, nxt_runtime_t *rt,
    nxt_router_temp_conf_t *tmcf);
static nxt_int_t nxt_router_thread_create(nxt_task_t *task, nxt_runtime_t *rt,
    nxt_event_engine_t *engine);
static void nxt_router_apps_sort(nxt_task_t *task, nxt_router_t *router,
    nxt_router_temp_conf_t *tmcf);

static void nxt_router_engines_post(nxt_router_t *router,
    nxt_router_temp_conf_t *tmcf);
static void nxt_router_engine_post(nxt_event_engine_t *engine,
    nxt_work_t *jobs);

static void nxt_router_thread_start(void *data);
static void nxt_router_listen_socket_create(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_listen_socket_update(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_listen_socket_delete(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_worker_thread_quit(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_listen_socket_close(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_thread_exit_handler(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_listen_socket_release(nxt_task_t *task,
    nxt_socket_conf_t *skcf);
static void nxt_router_conf_release(nxt_task_t *task,
    nxt_socket_conf_joint_t *joint);

static void nxt_router_app_port_ready(nxt_task_t *task,
    nxt_port_recv_msg_t *msg, void *data);
static void nxt_router_app_port_error(nxt_task_t *task,
    nxt_port_recv_msg_t *msg, void *data);

static nxt_port_t * nxt_router_app_get_idle_port(nxt_app_t *app);
static void nxt_router_app_port_release(nxt_task_t *task, nxt_port_t *port,
    uint32_t request_failed, uint32_t got_response);
static nxt_int_t nxt_router_app_port(nxt_task_t *task, nxt_req_app_link_t *ra);

static void nxt_router_conn_init(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conn_http_header_parse(nxt_task_t *task, void *obj,
    void *data);
static nxt_sockaddr_t *nxt_router_local_addr(nxt_task_t *task, nxt_conn_t *c);
static void nxt_router_conn_http_body_read(nxt_task_t *task, void *obj,
    void *data);
static void nxt_router_process_http_request(nxt_task_t *task,
    nxt_conn_t *c, nxt_app_parse_ctx_t *ap);
static void nxt_router_app_prepare_request(nxt_task_t *task,
    nxt_req_app_link_t *ra);
static nxt_int_t nxt_python_prepare_msg(nxt_task_t *task, nxt_app_request_t *r,
    nxt_app_wmsg_t *wmsg);
static nxt_int_t nxt_php_prepare_msg(nxt_task_t *task, nxt_app_request_t *r,
    nxt_app_wmsg_t *wmsg);
static nxt_int_t nxt_go_prepare_msg(nxt_task_t *task, nxt_app_request_t *r,
    nxt_app_wmsg_t *wmsg);
static void nxt_router_conn_ready(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conn_close(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conn_free(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conn_error(nxt_task_t *task, void *obj, void *data);
static void nxt_router_conn_timeout(nxt_task_t *task, void *obj, void *data);
static void nxt_router_app_timeout(nxt_task_t *task, void *obj, void *data);
static nxt_msec_t nxt_router_conn_timeout_value(nxt_conn_t *c, uintptr_t data);

static void nxt_router_gen_error(nxt_task_t *task, nxt_conn_t *c, int code,
    const char* str);

static nxt_router_t  *nxt_router;


static nxt_app_prepare_msg_t  nxt_app_prepare_msg[] = {
    nxt_python_prepare_msg,
    nxt_php_prepare_msg,
    nxt_go_prepare_msg,
};


nxt_int_t
nxt_router_start(nxt_task_t *task, void *data)
{
    nxt_int_t      ret;
    nxt_router_t   *router;
    nxt_runtime_t  *rt;

    rt = task->thread->runtime;

    ret = nxt_app_http_init(task, rt);
    if (nxt_slow_path(ret != NXT_OK)) {
        return ret;
    }

    router = nxt_zalloc(sizeof(nxt_router_t));
    if (nxt_slow_path(router == NULL)) {
        return NXT_ERROR;
    }

    nxt_queue_init(&router->engines);
    nxt_queue_init(&router->sockets);
    nxt_queue_init(&router->apps);

    nxt_router = router;

    return NXT_OK;
}


static void
nxt_router_start_worker_handler(nxt_task_t *task, nxt_port_t *port, void *data)
{
    size_t         size;
    uint32_t       stream;
    nxt_app_t      *app;
    nxt_buf_t      *b;
    nxt_port_t     *main_port;
    nxt_runtime_t  *rt;

    app = data;

    rt = task->thread->runtime;
    main_port = rt->port_by_type[NXT_PROCESS_MAIN];

    nxt_debug(task, "app '%V' %p start worker", &app->name, app);

    size = app->name.length + 1 + app->conf.length;

    b = nxt_buf_mem_ts_alloc(task, task->thread->engine->mem_pool, size);

    if (nxt_slow_path(b == NULL)) {
        goto failed;
    }

    nxt_buf_cpystr(b, &app->name);
    *b->mem.free++ = '\0';
    nxt_buf_cpystr(b, &app->conf);

    stream = nxt_port_rpc_register_handler(task, port,
                                           nxt_router_app_port_ready,
                                           nxt_router_app_port_error,
                                           -1, app);

    if (nxt_slow_path(stream == 0)) {
        nxt_mp_release(b->data, b);

        goto failed;
    }

    nxt_port_socket_write(task, main_port, NXT_PORT_MSG_START_WORKER, -1,
                          stream, port->id, b);

    return;

failed:

    nxt_thread_mutex_lock(&app->mutex);

    app->pending_workers--;

    nxt_thread_mutex_unlock(&app->mutex);

    nxt_router_app_use(task, app, -1);
}


static nxt_int_t
nxt_router_start_worker(nxt_task_t *task, nxt_app_t *app)
{
    nxt_int_t      res;
    nxt_port_t     *router_port;
    nxt_runtime_t  *rt;

    rt = task->thread->runtime;
    router_port = rt->port_by_type[NXT_PROCESS_ROUTER];

    nxt_router_app_use(task, app, 1);

    res = nxt_port_post(task, router_port, nxt_router_start_worker_handler,
                        app);

    if (res == NXT_OK) {
        return res;
    }

    nxt_thread_mutex_lock(&app->mutex);

    app->pending_workers--;

    nxt_thread_mutex_unlock(&app->mutex);

    nxt_router_app_use(task, app, -1);

    return NXT_ERROR;
}


nxt_inline void
nxt_router_ra_init(nxt_task_t *task, nxt_req_app_link_t *ra,
    nxt_req_conn_link_t *rc)
{
    nxt_event_engine_t  *engine;

    engine = task->thread->engine;

    nxt_memzero(ra, sizeof(nxt_req_app_link_t));

    ra->stream = rc->stream;
    ra->use_count = 1;
    ra->rc = rc;
    rc->ra = ra;
    ra->reply_port = engine->port;
    ra->ap = rc->ap;

    ra->work.handler = NULL;
    ra->work.task = &engine->task;
    ra->work.obj = ra;
    ra->work.data = engine;
}


nxt_inline nxt_req_app_link_t *
nxt_router_ra_create(nxt_task_t *task, nxt_req_app_link_t *ra_src)
{
    nxt_mp_t            *mp;
    nxt_req_app_link_t  *ra;

    if (ra_src->mem_pool != NULL) {
        return ra_src;
    }

    mp = ra_src->ap->mem_pool;

    ra = nxt_mp_retain(mp, sizeof(nxt_req_app_link_t));

    if (nxt_slow_path(ra == NULL)) {

        ra_src->rc->ra = NULL;
        ra_src->rc = NULL;

        return NULL;
    }

    nxt_router_ra_init(task, ra, ra_src->rc);

    ra->mem_pool = mp;

    return ra;
}


nxt_inline nxt_bool_t
nxt_router_msg_cancel(nxt_task_t *task, nxt_msg_info_t *msg_info,
    uint32_t stream)
{
    nxt_buf_t   *b, *next;
    nxt_bool_t  cancelled;

    if (msg_info->buf == NULL) {
        return 0;
    }

    cancelled = nxt_port_mmap_tracking_cancel(task, &msg_info->tracking,
                                              stream);

    if (cancelled) {
        nxt_debug(task, "stream #%uD: cancelled by router", stream);
    }

    for (b = msg_info->buf; b != NULL; b = next) {
        next = b->next;

        b->completion_handler = msg_info->completion_handler;

        if (b->is_port_mmap_sent) {
            b->is_port_mmap_sent = cancelled == 0;
            b->completion_handler(task, b, b->parent);
        }
    }

    msg_info->buf = NULL;

    return cancelled;
}


static void
nxt_router_ra_update_peer(nxt_task_t *task, nxt_req_app_link_t *ra);


static void
nxt_router_ra_update_peer_handler(nxt_task_t *task, void *obj, void *data)
{
    nxt_req_app_link_t  *ra;

    ra = obj;

    nxt_router_ra_update_peer(task, ra);

    nxt_router_ra_use(task, ra, -1);
}


static void
nxt_router_ra_update_peer(nxt_task_t *task, nxt_req_app_link_t *ra)
{
    nxt_event_engine_t   *engine;
    nxt_req_conn_link_t  *rc;

    engine = ra->work.data;

    if (task->thread->engine != engine) {
        nxt_router_ra_inc_use(ra);

        ra->work.handler = nxt_router_ra_update_peer_handler;
        ra->work.task = &engine->task;
        ra->work.next = NULL;

        nxt_debug(task, "ra stream #%uD post update peer to %p",
                  ra->stream, engine);

        nxt_event_engine_post(engine, &ra->work);

        return;
    }

    nxt_debug(task, "ra stream #%uD update peer", ra->stream);

    rc = ra->rc;

    if (rc != NULL && ra->app_port != NULL) {
        nxt_port_rpc_ex_set_peer(task, engine->port, rc, ra->app_port->pid);
    }

    nxt_router_ra_use(task, ra, -1);
}


static void
nxt_router_ra_release(nxt_task_t *task, nxt_req_app_link_t *ra)
{
    nxt_conn_t           *c;
    nxt_req_conn_link_t  *rc;

    nxt_assert(task->thread->engine == ra->work.data);
    nxt_assert(ra->use_count == 0);

    nxt_debug(task, "ra stream #%uD release", ra->stream);

    rc = ra->rc;

    if (rc != NULL) {
        c = rc->conn;

        if (nxt_slow_path(ra->err_code != 0)) {
            nxt_router_gen_error(task, c, ra->err_code, ra->err_str);

        } else {
            rc->app_port = ra->app_port;
            rc->msg_info = ra->msg_info;

            if (rc->app->timeout != 0) {
                c->read_timer.handler = nxt_router_app_timeout;
                nxt_timer_add(task->thread->engine, &c->read_timer,
                              rc->app->timeout);
            }

            ra->app_port = NULL;
            ra->msg_info.buf = NULL;
        }

        rc->ra = NULL;
        ra->rc = NULL;
    }

    if (ra->app_port != NULL) {
        nxt_router_app_port_release(task, ra->app_port, 0, 1);

        ra->app_port = NULL;
    }

    nxt_router_msg_cancel(task, &ra->msg_info, ra->stream);

    if (ra->mem_pool != NULL) {
        nxt_mp_release(ra->mem_pool, ra);
    }
}


static void
nxt_router_ra_release_handler(nxt_task_t *task, void *obj, void *data)
{
    nxt_req_app_link_t  *ra;

    ra = obj;

    nxt_assert(ra->work.data == data);

    nxt_atomic_fetch_add(&ra->use_count, -1);

    nxt_router_ra_release(task, ra);
}


static void
nxt_router_ra_use(nxt_task_t *task, nxt_req_app_link_t *ra, int i)
{
    int                 c;
    nxt_event_engine_t  *engine;

    c = nxt_atomic_fetch_add(&ra->use_count, i);

    if (i < 0 && c == -i) {
        engine = ra->work.data;

        if (task->thread->engine == engine) {
            nxt_router_ra_release(task, ra);

            return;
        }

        nxt_router_ra_inc_use(ra);

        ra->work.handler = nxt_router_ra_release_handler;
        ra->work.task = &engine->task;
        ra->work.next = NULL;

        nxt_debug(task, "ra stream #%uD post release to %p",
                  ra->stream, engine);

        nxt_event_engine_post(engine, &ra->work);
    }
}


nxt_inline void
nxt_router_ra_error(nxt_req_app_link_t *ra, int code, const char* str)
{
    ra->app_port = NULL;
    ra->err_code = code;
    ra->err_str = str;
}


nxt_inline nxt_bool_t
nxt_queue_chk_remove(nxt_queue_link_t *lnk)
{
    if (lnk->next != NULL) {
        nxt_queue_remove(lnk);

        lnk->next = NULL;

        return 1;
    }

    return 0;
}


nxt_inline void
nxt_router_rc_unlink(nxt_task_t *task, nxt_req_conn_link_t *rc)
{
    int                 ra_use_delta;
    nxt_req_app_link_t  *ra;

    if (rc->app_port != NULL) {
        nxt_router_app_port_release(task, rc->app_port, 0, 1);

        rc->app_port = NULL;
    }

    nxt_router_msg_cancel(task, &rc->msg_info, rc->stream);

    ra = rc->ra;

    if (ra != NULL) {
        rc->ra = NULL;
        ra->rc = NULL;

        ra_use_delta = 0;

        nxt_thread_mutex_lock(&rc->app->mutex);

        if (ra->link_app_requests.next == NULL
            && ra->link_port_pending.next == NULL)
        {
            ra = NULL;

        } else {
            ra_use_delta -= nxt_queue_chk_remove(&ra->link_app_requests);
            ra_use_delta -= nxt_queue_chk_remove(&ra->link_port_pending);
        }

        nxt_thread_mutex_unlock(&rc->app->mutex);

        if (ra != NULL) {
            nxt_router_ra_use(task, ra, ra_use_delta);
        }
    }

    if (rc->app != NULL) {
        nxt_router_app_use(task, rc->app, -1);

        rc->app = NULL;
    }

    if (rc->ap != NULL) {
        nxt_app_http_req_done(task, rc->ap);

        rc->ap = NULL;
    }

    nxt_queue_remove(&rc->link);

    rc->conn = NULL;
}


void
nxt_router_new_port_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
{
    nxt_port_new_port_handler(task, msg);

    if (msg->port_msg.stream == 0) {
        return;
    }

    if (msg->u.new_port == NULL
        || msg->u.new_port->type != NXT_PROCESS_WORKER)
    {
        msg->port_msg.type = _NXT_PORT_MSG_RPC_ERROR;
    }

    nxt_port_rpc_handler(task, msg);
}


void
nxt_router_conf_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
{
    nxt_int_t               ret;
    nxt_buf_t               *b;
    nxt_router_temp_conf_t  *tmcf;

    tmcf = nxt_router_temp_conf(task);
    if (nxt_slow_path(tmcf == NULL)) {
        return;
    }

    nxt_debug(task, "nxt_router_conf_data_handler(%d): %*s",
              nxt_buf_used_size(msg->buf),
              nxt_buf_used_size(msg->buf), msg->buf->mem.pos);

    b = nxt_buf_chk_make_plain(tmcf->conf->mem_pool, msg->buf, msg->size);

    nxt_assert(b != NULL);

    tmcf->conf->router = nxt_router;
    tmcf->stream = msg->port_msg.stream;
    tmcf->port = nxt_runtime_port_find(task->thread->runtime,
                                       msg->port_msg.pid,
                                       msg->port_msg.reply_port);

    ret = nxt_router_conf_create(task, tmcf, b->mem.pos, b->mem.free);

    if (nxt_fast_path(ret == NXT_OK)) {
        nxt_router_conf_apply(task, tmcf, NULL);

    } else {
        nxt_router_conf_error(task, tmcf);
    }
}


static void
nxt_router_worker_remove_pid(nxt_task_t *task, nxt_port_t *port, void *data)
{
    union {
        nxt_pid_t  removed_pid;
        void       *data;
    } u;

    u.data = data;

    nxt_port_rpc_remove_peer(task, port, u.removed_pid);
}


void
nxt_router_remove_pid_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
{
    nxt_event_engine_t  *engine;

    nxt_port_remove_pid_handler(task, msg);

    if (msg->port_msg.stream == 0) {
        return;
    }

    nxt_queue_each(engine, &nxt_router->engines, nxt_event_engine_t, link0)
    {
        nxt_port_post(task, engine->port, nxt_router_worker_remove_pid,
                      msg->u.data);
    }
    nxt_queue_loop;

    msg->port_msg.type = _NXT_PORT_MSG_RPC_ERROR;

    nxt_port_rpc_handler(task, msg);
}


static nxt_router_temp_conf_t *
nxt_router_temp_conf(nxt_task_t *task)
{
    nxt_mp_t                *mp, *tmp;
    nxt_router_conf_t       *rtcf;
    nxt_router_temp_conf_t  *tmcf;

    mp = nxt_mp_create(1024, 128, 256, 32);
    if (nxt_slow_path(mp == NULL)) {
        return NULL;
    }

    rtcf = nxt_mp_zget(mp, sizeof(nxt_router_conf_t));
    if (nxt_slow_path(rtcf == NULL)) {
        goto fail;
    }

    rtcf->mem_pool = mp;

    tmp = nxt_mp_create(1024, 128, 256, 32);
    if (nxt_slow_path(tmp == NULL)) {
        goto fail;
    }

    tmcf = nxt_mp_zget(tmp, sizeof(nxt_router_temp_conf_t));
    if (nxt_slow_path(tmcf == NULL)) {
        goto temp_fail;
    }

    tmcf->mem_pool = tmp;
    tmcf->conf = rtcf;
    tmcf->count = 1;
    tmcf->engine = task->thread->engine;

    tmcf->engines = nxt_array_create(tmcf->mem_pool, 4,
                                     sizeof(nxt_router_engine_conf_t));
    if (nxt_slow_path(tmcf->engines == NULL)) {
        goto temp_fail;
    }

    nxt_queue_init(&tmcf->deleting);
    nxt_queue_init(&tmcf->keeping);
    nxt_queue_init(&tmcf->updating);
    nxt_queue_init(&tmcf->pending);
    nxt_queue_init(&tmcf->creating);

    nxt_queue_init(&tmcf->apps);
    nxt_queue_init(&tmcf->previous);

    return tmcf;

temp_fail:

    nxt_mp_destroy(tmp);

fail:

    nxt_mp_destroy(mp);

    return NULL;
}


static void
nxt_router_conf_apply(nxt_task_t *task, void *obj, void *data)
{
    nxt_int_t                    ret;
    nxt_router_t                 *router;
    nxt_runtime_t                *rt;
    nxt_queue_link_t             *qlk;
    nxt_socket_conf_t            *skcf;
    nxt_router_temp_conf_t       *tmcf;
    const nxt_event_interface_t  *interface;

    tmcf = obj;

    qlk = nxt_queue_first(&tmcf->pending);

    if (qlk != nxt_queue_tail(&tmcf->pending)) {
        nxt_queue_remove(qlk);
        nxt_queue_insert_tail(&tmcf->creating, qlk);

        skcf = nxt_queue_link_data(qlk, nxt_socket_conf_t, link);

        nxt_router_listen_socket_rpc_create(task, tmcf, skcf);

        return;
    }

    rt = task->thread->runtime;