Introducing the shared application port.

This is the port shared between all application processes which use it to pass
requests for processing.  Using it significantly simplifies the request
processing code in the router.  The drawback is 2 more file descriptors per each
configured application and more complex libunit message wait/read code.

src/nodejs/unit-http/unit.cpp

@@ -20,7 +20,7 @@ napi_ref Unit::constructor_;
 
 struct port_data_t {
     nxt_unit_ctx_t      *ctx;
-    nxt_unit_port_id_t  port_id;
+    nxt_unit_port_t     *port;
     uv_poll_t           poll;
 };
 
@@ -351,7 +351,11 @@ Unit::shm_ack_handler(nxt_unit_ctx_t *ctx)
 static void
 nxt_uv_read_callback(uv_poll_t *handle, int status, int events)
 {
-    nxt_unit_run_once((nxt_unit_ctx_t *) handle->data);
+    port_data_t  *data;
+
+    data = (port_data_t *) handle->data;
+
+    nxt_unit_process_port_msg(data->ctx, data->port);
 }
 
 
@@ -396,21 +400,14 @@ Unit::add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port)
         port->data = data;
 
         data->ctx = ctx;
-        data->port_id = port->id;
-        data->poll.data = ctx;
+        data->port = port;
+        data->poll.data = data;
     }
 
     return NXT_UNIT_OK;
 }
 
 
-inline bool
-operator == (const nxt_unit_port_id_t &p1, const nxt_unit_port_id_t &p2)
-{
-    return p1.pid == p2.pid && p1.id == p2.id;
-}
-
-
 void
 Unit::remove_port(nxt_unit_t *unit, nxt_unit_port_t *port)
 {
@@ -419,10 +416,9 @@ Unit::remove_port(nxt_unit_t *unit, nxt_unit_port_t *port)
     if (port->data != NULL) {
         data = (port_data_t *) port->data;
 
-        if (data->port_id == port->id) {
+        if (data->port == port) {
             uv_poll_stop(&data->poll);
 
-            data->poll.data = data;
             uv_close((uv_handle_t *) &data->poll, delete_port_data);
         }
     }