port-serial: allow deciding whether the command is queued last or run next

By default all the commands we were sending through the serial port
were added at the tail of the pending queue, but we may want to queue
them at the head in very specific cases (e.g. while sending an SMS).

plugins/mbm/mm-broadband-modem-mbm.c

@@ -1262,7 +1262,8 @@ gps_enabled_ready (MMBaseModem *self,
             mm_port_serial_command (MM_PORT_SERIAL (gps_port),
                                     buf,
                                     3,
-                                    FALSE,
+                                    FALSE, /* never cached */
+                                    FALSE, /* always queued last */
                                     NULL,
                                     NULL,
                                     NULL);

src/mm-port-serial-at.c

@@ -427,6 +427,7 @@ mm_port_serial_at_command (MMPortSerialAt *self,
                             buf,
                             timeout_seconds,
                             allow_cached,
+                            FALSE, /* always queued last */
                             cancellable,
                             (GAsyncReadyCallback)serial_command_ready,
                             simple);

src/mm-port-serial-qcdm.c

@@ -193,6 +193,7 @@ mm_port_serial_qcdm_command (MMPortSerialQcdm *self,
                             command,
                             timeout_seconds,
                             FALSE, /* never cached */
+                            FALSE, /* always queued last */
                             cancellable,
                             (GAsyncReadyCallback)serial_command_ready,
                             task);

src/mm-port-serial.c

@@ -163,6 +163,7 @@ mm_port_serial_command (MMPortSerial *self,
                         GByteArray *command,
                         guint32 timeout_seconds,
                         gboolean allow_cached,
+                        gboolean run_next,
                         GCancellable *cancellable,
                         GAsyncReadyCallback callback,
                         gpointer user_data)
@@ -203,7 +204,12 @@ mm_port_serial_command (MMPortSerial *self,
     if (!allow_cached)
         port_serial_set_cached_reply (self, ctx->command, NULL);
 
-    g_queue_push_tail (self->priv->queue, ctx);
+    /* If requested to run next, push to the head of the queue so that it really is
+     * the next one sent */
+    if (run_next)
+        g_queue_push_head (self->priv->queue, ctx);
+    else
+        g_queue_push_tail (self->priv->queue, ctx);
 
     if (g_queue_get_length (self->priv->queue) == 1)
         port_serial_schedule_queue_process (self, 0);

src/mm-port-serial.h

@@ -144,6 +144,7 @@ void        mm_port_serial_command        (MMPortSerial *self,
                                            GByteArray *command,
                                            guint32 timeout_seconds,
                                            gboolean allow_cached,
+                                           gboolean run_next,
                                            GCancellable *cancellable,
                                            GAsyncReadyCallback callback,
                                            gpointer user_data);