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-rw-r--r--advtrains_line_automation/scheduler.lua107
1 files changed, 107 insertions, 0 deletions
diff --git a/advtrains_line_automation/scheduler.lua b/advtrains_line_automation/scheduler.lua
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+-- scheduler.lua
+-- Implementation of a Railway time schedule queue
+-- In contrast to the LuaATC interrupt queue, this one can handle many different
+-- event receivers. This is done by registering a callback with the scheduler
+
+local ln = advtrains.lines
+local sched = {}
+
+local UNITS_THRESH = 10
+local MAX_PER_ITER = 10
+
+local callbacks = {}
+--Function signature is function(d)
+function sched.register_callback(e, func)
+ callbacks[e] = func
+end
+
+--[[
+{
+ t = <railway time in seconds>
+ e = <handler callback>
+ d = <data table>
+ u = <unit identifier>
+}
+The "unit identifier" is there to prevent schedule overflows. It can be, for example, the position hash
+of a node or a train ID. If the number of schedules for a unit exceeds UNITS_THRESH, further schedules are
+blocked.
+]]--
+local queue = {}
+
+local units_cnt = {}
+
+function sched.load(data)
+ if data then
+ for i,elem in ipairs(data) do
+ table.insert(queue, elem)
+ units_cnt[elem.u] = (units_cnt[elem.u] or 0) + 1
+ end
+ end
+end
+function sched.save()
+ return queue
+end
+
+function sched.run()
+ local ctime = ln.rwt.get_time()
+ local cnt = 0
+ local ucn, elem
+ while cnt <= MAX_PER_ITER do
+ elem = queue[1]
+ if elem and elem.t <= ctime then
+ table.remove(queue, 1)
+ if callbacks[elem.e] then
+ -- run it
+ callbacks[elem.e](elem.d)
+ else
+ atwarn("No callback to handle schedule",elem)
+ end
+ cnt=cnt+1
+ ucn = units_cnt[elem.u]
+ if ucn and ucn>0 then
+ units_cnt[elem.u] = ucn - 1
+ end
+ else
+ break
+ end
+ end
+end
+
+function sched.enqueue(rwtime, handler, evtdata, unitid, unitlim)
+ local qtime = ln.rwt.to_secs(rwtime)
+ assert(type(handler)=="string")
+ assert(type(unitid)=="string")
+ assert(type(unitlim)=="number")
+
+ local cnt=1
+ local ucn, elem
+
+ ucn = (units_cnt[unitid] or 0)
+ local ulim=(unitlim or UNITS_THRESH)
+ if ucn >= ulim then
+ atwarn("Scheduler: discarding enqueue for",handler,"(limit",ulim,") because unit",unitid,"has already",ucn,"schedules enqueued")
+ return false
+ end
+
+ while true do
+ elem = queue[cnt]
+ if not elem or elem.t > qtime then
+ table.insert(queue, cnt, {
+ t=qtime,
+ e=handler,
+ d=evtdata,
+ u=unitid,
+ })
+ units_cnt[unitid] = ucn + 1
+ return true
+ end
+ cnt = cnt+1
+ end
+end
+
+function sched.enqueue_in(rwtime, handler, evtdata, unitid, unitlim)
+ local ctime = ln.rwt.get_time()
+ sched.enqueue(ctime + rwtime, handler, evtdata, unitid, unitlim)
+end
+
+ln.sched = sched