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package tickrunner
import (
"context"
"time"
)
// Run runs a task at a given periodic interval, or as requested over a channel.
// If many requests come in close to the same time, only run the task once.
// Callers can ask for the task to be run within a given amount of time, which
// overrides defaultReqDelay. Sending a zero to the channel runs it after defaukltReqDelay.
func Run(ctx context.Context, f func(), periodicInterval time.Duration, defaultReqDelay time.Duration) chan time.Duration {
runChan := make(chan time.Duration)
go func() {
nextRunTime := time.Now().Add(periodicInterval)
for {
select {
case <-time.After(time.Until(nextRunTime)):
nextRunTime = time.Now().Add(periodicInterval)
f()
case req := <-runChan:
proposedTime := time.Now()
if req == 0 {
proposedTime = proposedTime.Add(defaultReqDelay)
} else {
proposedTime = proposedTime.Add(req)
}
if proposedTime.Before(nextRunTime) {
nextRunTime = proposedTime
}
case <-ctx.Done():
return
}
}
}()
return runChan
}
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