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Fix issue with long wait for passed timer [bugfix] (#12221)

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* Fix issue with long wait for passed timer [bugfix]

This fixes a small issue where a timer that had been completed while
code executed would still wait for more events before being considered
completed. This would in some scenarios incur a 500ms delay to the
completion of a timer.

* Refactor logic into

* Add test case based on original issue

* Use longer timeouts to be more lenient in checking

* Revert to short timeouts, but widen the accepted range

* Widen accepted range further, it is meant to check for a 500ms delay after all

* Increase poll timeout to make it easier to detect mistakes
This commit is contained in:
PMunch 2019-09-22 07:24:14 +02:00 • committed by Andreas Rumpf
commit 2565d3d102
2 changed files with 61 additions and 3 deletions
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12
lib/pure/asyncdispatch.nim
View file

@ -210,7 +210,12 @@ proc processPendingCallbacks(p: PDispatcherBase; didSomeWork: var bool) =
cb() cb()
didSomeWork = true didSomeWork = true
proc adjustTimeout(pollTimeout: int, nextTimer: Option[int]): int {.inline.} = proc adjustTimeout(
p: PDispatcherBase, pollTimeout: int, nextTimer: Option[int]
): int {.inline.} =
if p.callbacks.len != 0:
return 0
if nextTimer.isNone() or pollTimeout == -1: if nextTimer.isNone() or pollTimeout == -1:
return pollTimeout return pollTimeout
@ -324,7 +329,7 @@ when defined(windows) or defined(nimdoc):
result = false result = false
let nextTimer = processTimers(p, result) let nextTimer = processTimers(p, result)
let at = adjustTimeout(timeout, nextTimer) let at = adjustTimeout(p, timeout, nextTimer)
var llTimeout = var llTimeout =
if at == -1: winlean.INFINITE if at == -1: winlean.INFINITE
else: at.int32 else: at.int32
@ -1284,7 +1289,8 @@ else:
result = false result = false
var keys: array[64, ReadyKey] var keys: array[64, ReadyKey]
let nextTimer = processTimers(p, result) let nextTimer = processTimers(p, result)
var count = p.selector.selectInto(adjustTimeout(timeout, nextTimer), keys) var count =
p.selector.selectInto(adjustTimeout(p, timeout, nextTimer), keys)
for i in 0..<count: for i in 0..<count:
let fd = keys[i].fd.AsyncFD let fd = keys[i].fd.AsyncFD
let events = keys[i].events let events = keys[i].events

52
tests/async/t12221.nim Normal file
View file

@ -0,0 +1,52 @@
import asyncdispatch, os, times
proc doubleSleep(hardSleep: int) {.async.} =
await sleepAsync(100)
sleep(hardSleep)
template assertTime(target, timeTook: float): untyped {.dirty.} =
assert(timeTook*1000 > target - 1000, "Took too short, should've taken " &
$target & "ms, but took " & $(timeTook*1000) & "ms")
assert(timeTook*1000 < target + 1000, "Took too long, should've taken " &
$target & "ms, but took " & $(timeTook*1000) & "ms")
var
start: float
fut: Future[void]
# NOTE: this uses poll(3000) to limit timing error potential.
start = epochTime()
fut = sleepAsync(50) and sleepAsync(150) and doubleSleep(40)
while not fut.finished:
poll(3000)
assertTime(150, epochTime() - start)
start = epochTime()
fut = sleepAsync(50) and sleepAsync(150) and doubleSleep(100)
while not fut.finished:
poll(3000)
assertTime(200, epochTime() - start)
start = epochTime()
fut = sleepAsync(50) and sleepAsync(150) and doubleSleep(40) and sleepAsync(300)
while not fut.finished:
poll(3000)
assertTime(300, epochTime() - start)
start = epochTime()
fut = sleepAsync(50) and sleepAsync(150) and doubleSleep(100) and sleepAsync(300)
while not fut.finished:
poll(3000)
assertTime(300, epochTime() - start)
start = epochTime()
fut = (sleepAsync(50) and sleepAsync(150) and doubleSleep(40)) or sleepAsync(700)
while not fut.finished:
poll(3000)
assertTime(150, epochTime() - start)
start = epochTime()
fut = (sleepAsync(50) and sleepAsync(150) and doubleSleep(100)) or sleepAsync(700)
while not fut.finished:
poll(3000)
assertTime(200, epochTime() - start)