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Diffstat (limited to 'indra/newview/scripts/lua/require/timers.lua')
| -rw-r--r-- | indra/newview/scripts/lua/require/timers.lua | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/indra/newview/scripts/lua/require/timers.lua b/indra/newview/scripts/lua/require/timers.lua new file mode 100644 index 0000000000..ab1615ffbf --- /dev/null +++ b/indra/newview/scripts/lua/require/timers.lua @@ -0,0 +1,122 @@ +-- Access to the viewer's time-delay facilities + +local leap = require 'leap' +local util = require 'util' + +local timers = {} + +local function dbg(...) end +-- local dbg = require 'printf' + +timers.Timer = {} + +-- delay: time in seconds until callback +-- callback: 'wait', or function to call when timer fires (self:tick if nil) +-- iterate: if non-nil, call callback repeatedly until it returns non-nil +-- (ignored if 'wait') +function timers.Timer:new(delay, callback, iterate) + local obj = setmetatable({}, self) + self.__index = self + + if callback == 'wait' then + dbg('scheduleAfter(%d):', delay) + sequence = leap.generate('Timers', {op='scheduleAfter', after=delay}) + -- ignore the immediate return + dbg('scheduleAfter(%d) -> %s', delay, + sequence.next()) + -- this call is where we wait for real + dbg('next():') + dbg('next() -> %s', + sequence.next()) + sequence.done() + return + end + + callback = callback or function() obj:tick() end + + local calls = 0 + if iterate then + -- With iterative timers, beware of running a timer callback which + -- performs async actions lasting longer than the timer interval. The + -- lengthy callback suspends, allowing leap to retrieve the next + -- event, which is a timer tick. leap calls a new instance of the + -- callback, even though the previous callback call is still + -- suspended... etc. 'in_callback' defends against that recursive + -- case. Rather than re-enter the suspended callback, drop the + -- too-soon timer event. (We could count the too-soon timer events and + -- iterate calling the callback, but it's a bathtub problem: the + -- callback could end up getting farther and farther behind.) + local in_callback = false + obj.id = leap.eventstream( + 'Timers', + {op='scheduleEvery', every=delay}, + function (event) + local reqid = event.reqid + calls += 1 + if calls == 1 then + dbg('timer(%s) first callback', reqid) + -- discard the first (immediate) response: don't call callback + return nil + else + if in_callback then + dbg('dropping timer(%s) callback %d', reqid, calls) + else + dbg('timer(%s) callback %d', reqid, calls) + in_callback = true + local ret = callback(event) + in_callback = false + return ret + end + end + end + ).reqid + else -- (not iterate) + obj.id = leap.eventstream( + 'Timers', + {op='scheduleAfter', after=delay}, + function (event) + calls += 1 + -- Arrange to return nil the first time, true the second. This + -- callback is called immediately with the response to + -- 'scheduleAfter', and if we immediately returned true, we'd + -- be done, and the subsequent timer event would be discarded. + if calls == 1 then + -- Caller doesn't expect an immediate callback. + return nil + else + callback(event) + -- Since caller doesn't want to iterate, the value + -- returned by the callback is irrelevant: just stop after + -- this one and only call. + return true + end + end + ).reqid + end + + return obj +end + +util.classctor(timers.Timer) + +function timers.Timer:tick() + error('Pass a callback to Timer:new(), or override Timer:tick()') +end + +function timers.Timer:cancel() + local ok = leap.request('Timers', {op='cancel', id=self.id}).ok + leap.cancelreq(self.id) + return ok +end + +function timers.Timer:isRunning() + return leap.request('Timers', {op='isRunning', id=self.id}).running +end + +-- returns (true, seconds left) for a live timer, else (false, 0) +function timers.Timer:timeUntilCall() + local result = leap.request('Timers', {op='timeUntilCall', id=self.id}) + return result.ok, result.remaining +end + +return timers |