util/timer.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8
   9 local indexedbheap = require "util.indexedbheap";
  10 local log = require "util.logger".init("timer");
  11 local server = require "net.server";
  12 local get_time = require "util.time".now
  13 local type = type;
  14 local debug_traceback = debug.traceback;
  15 local tostring = tostring;
  16 local xpcall = require "util.xpcall".xpcall;
  17 local math_max = math.max;
  18
  19 local _ENV = nil;
  20 -- luacheck: std none
  21
  22 local _add_task = server.add_task;
  23
  24 local _server_timer;
  25 local _active_timers = 0;
  26 local h = indexedbheap.create();
  27 local params = {};
  28 local next_time = nil;
  29 local function _traceback_handler(err) log("error", "Traceback[timer]: %s", debug_traceback(tostring(err), 2)); end
  30 local function _on_timer(now)
  31         local peek;
  32         while true do
  33                 peek = h:peek();
  34                 if peek == nil or peek > now then break; end
  35                 local _, callback, id = h:pop();
  36                 local param = params[id];
  37                 params[id] = nil;
  38                 --item(now, id, _param);
  39                 local success, err = xpcall(callback, _traceback_handler, now, id, param);
  40                 if success and type(err) == "number" then
  41                         h:insert(callback, err + now, id); -- re-add
  42                         params[id] = param;
  43                 end
  44         end
  45
  46         if peek ~= nil and _active_timers > 1 and peek == next_time then
  47                 -- Another instance of _on_timer already set next_time to the same value,
  48                 -- so it should be safe to not renew this timer event
  49                 peek = nil;
  50         else
  51                 next_time = peek;
  52         end
  53
  54         if peek then
  55                 -- peek is the time of the next event
  56                 return peek - now;
  57         end
  58         _active_timers = _active_timers - 1;
  59 end
  60 local function add_task(delay, callback, param)
  61         local current_time = get_time();
  62         local event_time = current_time + delay;
  63
  64         local id = h:insert(callback, event_time);
  65         params[id] = param;
  66         if next_time == nil or event_time < next_time then
  67                 next_time = event_time;
  68                 if _server_timer then
  69                         _server_timer:close();
  70                         _server_timer = nil;
  71                 else
  72                         _active_timers = _active_timers + 1;
  73                 end
  74                 _server_timer = _add_task(next_time - current_time, _on_timer);
  75         end
  76         return id;
  77 end
  78 local function stop(id)
  79         params[id] = nil;
  80         local result, item, result_sync = h:remove(id);
  81         local peek = h:peek();
  82         if peek ~= next_time and _server_timer then
  83                 next_time = peek;
  84                 _server_timer:close();
  85                 if next_time ~= nil then
  86                         _server_timer = _add_task(math_max(next_time - get_time(), 0), _on_timer);
  87                 end
  88         end
  89         return result, item, result_sync;
  90 end
  91 local function reschedule(id, delay)
  92         local current_time = get_time();
  93         local event_time = current_time + delay;
  94         h:reprioritize(id, delay);
  95         if next_time == nil or event_time < next_time then
  96                 next_time = event_time;
  97                 _add_task(next_time - current_time, _on_timer);
  98         end
  99         return id;
 100 end
 101
 102 return {
 103         add_task = add_task;
 104         stop = stop;
 105         reschedule = reschedule;
 106 };
 107