55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
package common
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import (
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"fmt"
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"math"
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"time"
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)
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var RetryExhaustedError error = fmt.Errorf("Function never succeeded in Retry")
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// RetryableFunc performs an action and returns a bool indicating whether the
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// function is done, or if it should keep retrying, and an error which will
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// abort the retry and be returned by the Retry function. The 0-indexed attempt
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// is passed with each call.
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type RetryableFunc func(uint) (bool, error)
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/*
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Retry retries a function up to numTries times with exponential backoff.
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If numTries == 0, retry indefinitely.
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If interval == 0, Retry will not delay retrying and there will be no
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exponential backoff.
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If maxInterval == 0, maxInterval is set to +Infinity.
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Intervals are in seconds.
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Returns an error if initial > max intervals, if retries are exhausted, or if the passed function returns
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an error.
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*/
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func Retry(initialInterval float64, maxInterval float64, numTries uint, function RetryableFunc) error {
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if maxInterval == 0 {
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maxInterval = math.Inf(1)
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} else if initialInterval < 0 || initialInterval > maxInterval {
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return fmt.Errorf("Invalid retry intervals (negative or initial < max). Initial: %f, Max: %f.", initialInterval, maxInterval)
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}
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var err error
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done := false
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interval := initialInterval
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for i := uint(0); !done && (numTries == 0 || i < numTries); i++ {
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done, err = function(i)
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if err != nil {
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return err
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}
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if !done {
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// Retry after delay. Calculate next delay.
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time.Sleep(time.Duration(interval) * time.Second)
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interval = math.Min(interval*2, maxInterval)
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}
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}
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if !done {
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return RetryExhaustedError
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}
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return nil
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}
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