+local function guarder()
+ local guards = {};
+ return function (id, func)
+ local thread = coroutine.running();
+ if not thread then
+ error("Not running in an async context, see http://prosody.im/doc/developers/async");
+ end
+ local guard = guards[id];
+ if not guard then
+ guard = {};
+ guards[id] = guard;
+ log("debug", "New guard!");
+ else
+ table.insert(guard, thread);
+ log("debug", "Guarded. %d threads waiting.", #guard)
+ coroutine.yield("wait");
+ end
+ local function exit()
+ local next_waiting = table.remove(guard, 1);
+ if next_waiting then
+ log("debug", "guard: Executing next waiting thread (%d left)", #guard)
+ runner_continue(next_waiting);
+ else
+ log("debug", "Guard off duty.")
+ guards[id] = nil;
+ end
+ end
+ if func then
+ func();
+ exit();
+ return;
+ end
+ return exit;
+ end;
+end
+