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Merge pull request #423 from jzelinskie/sleep-updater

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updater: sleep before continuing the lock loop
This commit is contained in:
Jimmy Zelinskie 2017-06-29 15:59:10 -04:00 committed by GitHub
commit 74edd854ee
1 changed files with 27 additions and 12 deletions
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29
updater.go
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@ -35,6 +35,7 @@ const (
updaterLockName = "updater"
updaterLockDuration = updaterLockRefreshDuration + time.Minute*2
updaterLockRefreshDuration = time.Minute * 8
updaterSleepBetweenLoopsDuration = time.Minute
)
var (
@ -124,7 +125,14 @@ func RunUpdater(config *UpdaterConfig, datastore database.Datastore, st *stopper
if stop {
break
}
// Sleep for a short duration to prevent pinning the CPU on a
// consistent failure.
if stopped := sleepUpdater(time.Now().Add(updaterSleepBetweenLoopsDuration), st); stopped {
break
}
continue
} else {
lockOwner, lockExpiration, err := datastore.FindLock(updaterLockName)
if err != nil {
@ -137,16 +145,10 @@ func RunUpdater(config *UpdaterConfig, datastore database.Datastore, st *stopper
}
}
// Sleep, but remain stoppable until approximately the next update time.
now := time.Now().UTC()
waitUntil := nextUpdate.Add(time.Duration(rand.ExpFloat64()/0.5) * time.Second)
log.WithField("scheduled time", waitUntil).Debug("next update attempt scheduled")
if !waitUntil.Before(now) {
if !st.Sleep(waitUntil.Sub(time.Now())) {
if stopped := sleepUpdater(nextUpdate, st); stopped {
break
}
}
}
// Clean resources.
for _, appenders := range vulnmdsrc.Appenders() {
@ -159,6 +161,19 @@ func RunUpdater(config *UpdaterConfig, datastore database.Datastore, st *stopper
log.Info("updater service stopped")
}
// sleepUpdater sleeps the updater for an approximate duration, but remains
// able to be cancelled by a stopper.
func sleepUpdater(approxWakeup time.Time, st *stopper.Stopper) (stopped bool) {
waitUntil := approxWakeup.Add(time.Duration(rand.ExpFloat64()/0.5) * time.Second)
log.WithField("scheduled time", waitUntil).Debug("updater sleeping")
if !waitUntil.Before(time.Now().UTC()) {
if !st.Sleep(waitUntil.Sub(time.Now())) {
return true
}
}
return false
}
// update fetches all the vulnerabilities from the registered fetchers, upserts
// them into the database and then sends notifications.
func update(datastore database.Datastore, firstUpdate bool) {