Added basic HTTP request processing in router.

- request to connection mapping in engine;
- requests queue in connection;
- engine port creation;
- connected ports hash for each process;
- engine port data messages processing (app responses);

src/nxt_conn.c

@@ -85,6 +85,8 @@ nxt_conn_create(nxt_mp_t *mp, nxt_task_t *task)
     nxt_conn_timer_init(&c->read_timer, c, c->socket.read_work_queue);
     nxt_conn_timer_init(&c->write_timer, c, c->socket.write_work_queue);
 
+    nxt_queue_init(&c->requests);
+
     nxt_log_debug(&c->log, "connections: %uD", thr->engine->connections);
 
     return c;
@@ -150,3 +152,35 @@ nxt_conn_work_queue_set(nxt_conn_t *c, nxt_work_queue_t *wq)
     c->read_timer.work_queue = wq;
     c->write_timer.work_queue = wq;
 }
+
+
+nxt_req_conn_link_t *
+nxt_conn_request_add(nxt_conn_t *c, nxt_req_id_t req_id)
+{
+    nxt_req_conn_link_t  *rc;
+
+    rc = nxt_mp_zalloc(c->mem_pool, sizeof(nxt_req_conn_link_t));
+    if (nxt_slow_path(rc == NULL)) {
+        nxt_thread_log_error(NXT_LOG_WARN, "failed to allocate req %08uxD "
+                             "to conn", req_id);
+        return NULL;
+    }
+
+    rc->req_id = req_id;
+    rc->conn = c;
+
+    nxt_queue_insert_tail(&c->requests, &rc->link);
+
+    return rc;
+}
+
+
+void
+nxt_conn_request_remove(nxt_conn_t *c, nxt_req_conn_link_t *rc)
+{
+    nxt_queue_remove(&rc->link);
+
+    nxt_mp_free(c->mem_pool, rc);
+}
+
+