drone/job/timer.go

122 lines
2.9 KiB
Go

// Copyright 2023 Harness, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package job
import (
"time"
)
const timerMaxDur = 30 * time.Minute
const timerMinDur = time.Nanosecond
type schedulerTimer struct {
timerAt time.Time
timer *time.Timer
edgy bool // if true, the next RescheduleEarlier call will trigger the timer immediately.
}
// newSchedulerTimer created new timer for the Scheduler. It is created to fire immediately.
func newSchedulerTimer() *schedulerTimer {
return &schedulerTimer{
timerAt: time.Now().Add(timerMinDur),
timer: time.NewTimer(timerMinDur),
}
}
// ResetAt resets the internal timer to trigger at the provided time.
// If the provided time is zero, it will schedule it to after the max duration.
func (t *schedulerTimer) ResetAt(next time.Time, edgy bool) time.Duration {
return t.resetAt(time.Now(), next, edgy)
}
func (t *schedulerTimer) resetAt(now, next time.Time, edgy bool) time.Duration {
var dur time.Duration
dur = next.Sub(now)
if dur < timerMinDur {
dur = timerMinDur
next = now.Add(dur)
} else if dur > timerMaxDur {
dur = timerMaxDur
next = now.Add(dur)
}
t.Stop()
t.edgy = edgy
t.timerAt = next
t.timer.Reset(dur)
return dur
}
// RescheduleEarlier will reset the timer if the new time is earlier than the previous time.
// Otherwise, the function does nothing and returns 0.
// Providing zero time triggers the timer if it's edgy, otherwise does nothing.
func (t *schedulerTimer) RescheduleEarlier(next time.Time) time.Duration {
return t.rescheduleEarlier(time.Now(), next)
}
func (t *schedulerTimer) rescheduleEarlier(now, next time.Time) time.Duration {
var dur time.Duration
switch {
case t.edgy:
// if the timer is edgy trigger it immediately
dur = timerMinDur
case next.IsZero():
// if the provided time is zero: trigger the timer if it's edgy otherwise do nothing
if !t.edgy {
return 0
}
dur = timerMinDur
case !next.Before(t.timerAt):
// do nothing if the timer is already scheduled to run sooner than the provided time
return 0
default:
dur = next.Sub(now)
if dur < timerMinDur {
dur = timerMinDur
}
}
next = now.Add(dur)
t.Stop()
t.timerAt = next
t.timer.Reset(dur)
return dur
}
func (t *schedulerTimer) Ch() <-chan time.Time {
return t.timer.C
}
func (t *schedulerTimer) Stop() {
// stop the timer
t.timer.Stop()
// consume the timer's tick if any
select {
case <-t.timer.C:
default:
}
t.timerAt = time.Time{}
}