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// Tideland Go Library - Time Extensions
//
// Copyright (C) 2009-2017 Frank Mueller / Tideland / Oldenburg / Germany
//
// All rights reserved. Use of this source code is governed
// by the new BSD license.
package timex
//--------------------
// IMPORTS
//--------------------
import (
"time"
"github.com/tideland/golib/errors"
)
//--------------------
// RETRY
//--------------------
// RetryStrategy describes how often the function in Retry is executed, the
// initial break between those retries, how much this time is incremented
// for each retry, and the maximum timeout.
type RetryStrategy struct {
Count int
Break time.Duration
BreakIncrement time.Duration
Timeout time.Duration
}
// ShortAttempt returns a predefined short retry strategy.
func ShortAttempt() RetryStrategy {
return RetryStrategy{
Count: 10,
Break: 50 * time.Millisecond,
BreakIncrement: 0,
Timeout: 5 * time.Second,
}
}
// MediumAttempt returns a predefined medium retry strategy.
func MediumAttempt() RetryStrategy {
return RetryStrategy{
Count: 50,
Break: 10 * time.Millisecond,
BreakIncrement: 10 * time.Millisecond,
Timeout: 30 * time.Second,
}
}
// LongAttempt returns a predefined long retry strategy.
func LongAttempt() RetryStrategy {
return RetryStrategy{
Count: 100,
Break: 10 * time.Millisecond,
BreakIncrement: 25 * time.Millisecond,
Timeout: 5 * time.Minute,
}
}
// Retry executes the passed function until it returns true or an error.
// These retries are restricted by the retry strategy.
func Retry(f func() (bool, error), rs RetryStrategy) error {
timeout := time.Now().Add(rs.Timeout)
sleep := rs.Break
for i := 0; i < rs.Count; i++ {
done, err := f()
if err != nil {
return err
}
if done {
return nil
}
if time.Now().After(timeout) {
return errors.New(ErrRetriedTooLong, errorMessages, rs.Timeout)
}
time.Sleep(sleep)
sleep += rs.BreakIncrement
}
return errors.New(ErrRetriedTooOften, errorMessages, rs.Count)
}
// EOF
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