77 lines
1.7 KiB
Go
77 lines
1.7 KiB
Go
![]() |
package util
|
||
|
|
||
|
import (
|
||
|
"time"
|
||
|
)
|
||
|
|
||
|
// AttemptStrategy is reused from the goamz package
|
||
|
|
||
|
// AttemptStrategy represents a strategy for waiting for an action
|
||
|
// to complete successfully. This is an internal type used by the
|
||
|
// implementation of other packages.
|
||
|
type AttemptStrategy struct {
|
||
|
Total time.Duration // total duration of attempt.
|
||
|
Delay time.Duration // interval between each try in the burst.
|
||
|
Min int // minimum number of retries; overrides Total
|
||
|
}
|
||
|
|
||
|
type Attempt struct {
|
||
|
strategy AttemptStrategy
|
||
|
last time.Time
|
||
|
end time.Time
|
||
|
force bool
|
||
|
count int
|
||
|
}
|
||
|
|
||
|
// Start begins a new sequence of attempts for the given strategy.
|
||
|
func (s AttemptStrategy) Start() *Attempt {
|
||
|
now := time.Now()
|
||
|
return &Attempt{
|
||
|
strategy: s,
|
||
|
last: now,
|
||
|
end: now.Add(s.Total),
|
||
|
force: true,
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Next waits until it is time to perform the next attempt or returns
|
||
|
// false if it is time to stop trying.
|
||
|
func (a *Attempt) Next() bool {
|
||
|
now := time.Now()
|
||
|
sleep := a.nextSleep(now)
|
||
|
if !a.force && !now.Add(sleep).Before(a.end) && a.strategy.Min <= a.count {
|
||
|
return false
|
||
|
}
|
||
|
a.force = false
|
||
|
if sleep > 0 && a.count > 0 {
|
||
|
time.Sleep(sleep)
|
||
|
now = time.Now()
|
||
|
}
|
||
|
a.count++
|
||
|
a.last = now
|
||
|
return true
|
||
|
}
|
||
|
|
||
|
func (a *Attempt) nextSleep(now time.Time) time.Duration {
|
||
|
sleep := a.strategy.Delay - now.Sub(a.last)
|
||
|
if sleep < 0 {
|
||
|
return 0
|
||
|
}
|
||
|
return sleep
|
||
|
}
|
||
|
|
||
|
// HasNext returns whether another attempt will be made if the current
|
||
|
// one fails. If it returns true, the following call to Next is
|
||
|
// guaranteed to return true.
|
||
|
func (a *Attempt) HasNext() bool {
|
||
|
if a.force || a.strategy.Min > a.count {
|
||
|
return true
|
||
|
}
|
||
|
now := time.Now()
|
||
|
if now.Add(a.nextSleep(now)).Before(a.end) {
|
||
|
a.force = true
|
||
|
return true
|
||
|
}
|
||
|
return false
|
||
|
}
|