core: add chaining helper functions to callback info

Helpful when chaining a number of commands together when you want
to schedule the callback info only after all of them complete.

src/mm-callback-info.c

@@ -91,6 +91,8 @@ mm_callback_info_schedule (MMCallbackInfo *info)
     g_return_if_fail (info->pending_id == 0);
     g_return_if_fail (info->called == FALSE);
 
+    g_warn_if_fail (info->chain_left == 0);
+
     info->pending_id = g_idle_add_full (G_PRIORITY_DEFAULT_IDLE, callback_info_do, info, callback_info_done);
 }
 
@@ -208,3 +210,24 @@ mm_callback_info_unref (MMCallbackInfo *info)
     }
 }
 
+void
+mm_callback_info_chain_start (MMCallbackInfo *info, guint num)
+{
+    g_return_if_fail (info != NULL);
+    g_return_if_fail (num > 0);
+    g_return_if_fail (info->chain_left == 0);
+
+    info->chain_left = num;
+}
+
+void
+mm_callback_info_chain_complete_one (MMCallbackInfo *info)
+{
+    g_return_if_fail (info != NULL);
+    g_return_if_fail (info->chain_left > 0);
+
+    info->chain_left--;
+    if (info->chain_left == 0)
+        mm_callback_info_schedule (info);
+}
+

src/mm-callback-info.h

@@ -25,6 +25,9 @@ typedef void (*MMCallbackInfoInvokeFn) (MMCallbackInfo *info);
 struct _MMCallbackInfo {
     guint32 refcount;
 
+    /* # of ops left in this callback chain */
+    guint32 chain_left;
+
     GData *qdata;
     MMModem *modem;
 
@@ -70,5 +73,8 @@ gpointer        mm_callback_info_get_data (MMCallbackInfo *info,
 MMCallbackInfo *mm_callback_info_ref (MMCallbackInfo *info);
 void            mm_callback_info_unref (MMCallbackInfo *info);
 
+void            mm_callback_info_chain_start (MMCallbackInfo *info, guint num);
+void            mm_callback_info_chain_complete_one (MMCallbackInfo *info);
+
 #endif /* MM_CALLBACK_INFO_H */