forked from TrueCloudLab/restic
69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
/*
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* Minio Go Library for Amazon S3 Compatible Cloud Storage
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* Copyright 2015-2017 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package minio
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import "time"
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// newRetryTimerContinous creates a timer with exponentially increasing delays forever.
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func (c Client) newRetryTimerContinous(unit time.Duration, cap time.Duration, jitter float64, doneCh chan struct{}) <-chan int {
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attemptCh := make(chan int)
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// normalize jitter to the range [0, 1.0]
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if jitter < NoJitter {
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jitter = NoJitter
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}
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if jitter > MaxJitter {
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jitter = MaxJitter
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}
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// computes the exponential backoff duration according to
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// https://www.awsarchitectureblog.com/2015/03/backoff.html
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exponentialBackoffWait := func(attempt int) time.Duration {
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// 1<<uint(attempt) below could overflow, so limit the value of attempt
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maxAttempt := 30
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if attempt > maxAttempt {
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attempt = maxAttempt
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}
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//sleep = random_between(0, min(cap, base * 2 ** attempt))
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sleep := unit * time.Duration(1<<uint(attempt))
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if sleep > cap {
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sleep = cap
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}
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if jitter != NoJitter {
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sleep -= time.Duration(c.random.Float64() * float64(sleep) * jitter)
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}
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return sleep
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}
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go func() {
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defer close(attemptCh)
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var nextBackoff int
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for {
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select {
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// Attempts starts.
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case attemptCh <- nextBackoff:
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nextBackoff++
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case <-doneCh:
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// Stop the routine.
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return
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}
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time.Sleep(exponentialBackoffWait(nextBackoff))
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}
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}()
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return attemptCh
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}
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