mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-07-26 06:38:42 +00:00
Ron Evans
e569dcfe38
* runtime: fix ticker not stopping when Stop races with its callback On the threads and cores schedulers, timer callbacks run concurrently with user goroutines. If Stop (or Reset) was called in the window after the node was popped but before its callback re-added it, removeTimer would not find the timer in the queue, so it would be re-added to timer anyway. Track timers whose callback is currently running in a firing list, and have removeTimer mark a firing timer as stopped so its callback does not re-add it. Also make the timers test drain robust: allow a possible in-flight tick delivered concurrently with Stop to settle before draining the channel. Signed-off-by: deadprogram <ron@hybridgroup.com> * runtime: fix Stop/Reset semantics when racing a firing timer callback Address review feedback on the ticker Stop-race fix. On the threads and cores schedulers a timer callback runs concurrently with user goroutines, which left several problems: - removeTimer reported a firing timer as successfully removed, so Stop/Reset could return true even though the callback had already started (wrong semantics, notably for AfterFunc). firingTimerStop now returns a bool and removeTimer no longer hands the still-firing node back to resetTimer. - The periodic advance (when += period) ran in timerCallback outside the scheduler timer lock. Move it into each scheduler's reAddTimer, under the lock and after the stopped check, so a concurrent Reset can't have its freshly-queued deadline corrupted. - resetTimer now sets when/period after removeTimer for the same reason. Add testdata/timer_stop_reset_race.go and TestTimerStopResetRace, which reproduce the stop-while-firing and reset-while-firing races via the runtime timer linkname hooks. Signed-off-by: deadprogram <ron@hybridgroup.com> * runtime: fix timer Stop/Reset race with firing periodic timers Signed-off-by: deadprogram <ron@hybridgroup.com> --------- Signed-off-by: deadprogram <ron@hybridgroup.com>
84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
package main
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import (
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"time"
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"unsafe"
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_ "unsafe"
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)
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func main() {
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testStopWhileFiring()
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testResetWhileFiring()
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println("timer stop/reset race tests done")
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}
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func testStopWhileFiring() {
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started := make(chan struct{})
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release := make(chan struct{})
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tim := newTimerWithCallback(time.Millisecond, 0, func(any, uintptr, int64) {
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close(started)
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<-release
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})
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<-started
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if stopTimer(tim) {
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println("fail: Stop returned true for a firing timer")
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} else {
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println("Stop returned false for firing timer")
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}
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close(release)
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}
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func testResetWhileFiring() {
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started := make(chan struct{})
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release := make(chan struct{})
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firedAgain := make(chan struct{}, 1)
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first := true
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tim := newTimerWithCallback(time.Millisecond, 5*time.Second, func(any, uintptr, int64) {
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if first {
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first = false
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close(started)
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<-release
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return
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}
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select {
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case firedAgain <- struct{}{}:
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default:
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}
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})
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<-started
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resetPeriodicTimer(tim, 20*time.Millisecond, 5*time.Second)
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close(release)
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time.Sleep(200 * time.Millisecond)
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select {
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case <-firedAgain:
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println("reset firing timer used reset deadline")
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default:
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println("fail: reset firing timer missed reset deadline")
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}
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stopTimer(tim)
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}
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func newTimerWithCallback(delay, period time.Duration, f func(any, uintptr, int64)) *time.Timer {
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return newTimer(runtimeNano()+int64(delay), int64(period), f, nil, nil)
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}
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func resetPeriodicTimer(tim *time.Timer, delay, period time.Duration) bool {
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return resetTimer(tim, runtimeNano()+int64(delay), int64(period))
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}
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//go:linkname newTimer time.newTimer
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func newTimer(when, period int64, f func(any, uintptr, int64), arg any, cp unsafe.Pointer) *time.Timer
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//go:linkname stopTimer time.stopTimer
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func stopTimer(tim *time.Timer) bool
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//go:linkname resetTimer time.resetTimer
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func resetTimer(tim *time.Timer, when, period int64) bool
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//go:linkname runtimeNano time.runtimeNano
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func runtimeNano() int64
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