Generic/cron.lua

   1 -- Functions we use here.
   2 local create = QuestHelper.create
   3 local createSortedList = QuestHelper.createSortedList
   4 local createCallback = QuestHelper.createCallback
   5 local release = QuestHelper.release
   6 local reference = QuestHelper.reference
   7 local array = QuestHelper.array
   8 local insert = table.insert
   9 local erase = table.remove
  10 local now = GetTime or os.time
  11
  12 -- The metatable for Cron objects.
  13 local Cron = {}
  14
  15 local function jobCmp(a, b)
  16   return a.time > b.time
  17 end
  18
  19 function Cron:onCreate()
  20   rawset(self, "jobs", createSortedList(jobCmp))
  21 end
  22
  23 function Cron:onRelease()
  24   local jobs = rawget(self, "jobs")
  25   for i, job in ipairs(jobs) do
  26     release(job.callback)
  27     release(job)
  28   end
  29   release(jobs)
  30 end
  31
  32 -- Will invoke callback 'wait' or more seconds from now, at some future invocation of poll.
  33 --
  34 -- If the callback returns a number, it will be invoked again in at least that number of seconds.
  35 --
  36 -- The callback is referenced and that reference will be released when the job is complete or
  37 -- the cron object itself is released.
  38 --
  39 -- If callback is actually a function, a callback is created from it using the additional arguments.
  40 -- Otherwise, any additional arguments are ignored.
  41 --
  42 -- You could probably get away with passing an event object here as if it were a callback.
  43 --
  44 -- Returns the passed or created callback.
  45 function Cron:start(wait, callback, ...)
  46   assert(type(wait) == "number", "Expected positive number.")
  47   local job= array(delta, callback)
  48   job.time = now()+wait
  49   job.callback = type(callback) == "function" and createCallback(callback, ...) or reference(callback)
  50   rawget(self, "jobs"):insert(job)
  51 end
  52
  53 -- Attempts to find a job with the specified callback and stop it.
  54 function Cron:stop(callback)
  55   local jobs = rawget(self, "jobs")
  56   for i, job in pairs(jobs) do
  57     if job.callback == callback then
  58       erase(jobs, i)
  59       release(job.callback)
  60       release(job)
  61       return
  62     end
  63   end
  64
  65   assert(false, "Callback wasn't handled.")
  66 end
  67
  68 -- Returns true if the cron object isn't tracking any objects.
  69 function Cron:empty()
  70   return #rawget(self, "jobs") == 0
  71 end
  72
  73 -- Will invoke the next callback that needs to be called, returning true if something happened, nil otherwise.
  74 function Cron:poll()
  75   local t = now()
  76   local jobs = rawget(self, "jobs")
  77   local i = #jobs
  78
  79   if i > 0 then
  80     local job = rawget(jobs, i)
  81
  82     if job.time < t then
  83       erase(jobs, i)
  84       local result = job.callback()
  85       if result then
  86         job.time = t+result
  87         insert(temp, job)
  88       else
  89         release(job.callback)
  90         release(job)
  91       end
  92
  93       return true
  94     end
  95   end
  96 end
  97
  98 -- Allow you to use cron object as if it were a function.
  99 Cron.__call = Cron.poll
 100
 101 Cron.__newindex = function()
 102   assert(false, "Shouldn't assign values.")
 103 end
 104
 105 Cron.__index = function(_, key)
 106   return rawget(Cron, key)
 107 end
 108
 109 local function createCron()
 110   return create(Cron)
 111 end
 112
 113 QuestHelper.createCron = createCron