forked from TrueCloudLab/restic
58 lines
1.4 KiB
Go
58 lines
1.4 KiB
Go
/*
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Copyright 2017 Google Inc. All Rights Reserved.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 spanner
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import (
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"math/rand"
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"time"
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)
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const (
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// minBackoff is the minimum backoff used by default.
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minBackoff = 1 * time.Second
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// maxBackoff is the maximum backoff used by default.
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maxBackoff = 32 * time.Second
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// jitter is the jitter factor.
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jitter = 0.4
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// rate is the rate of exponential increase in the backoff.
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rate = 1.3
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)
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var defaultBackoff = exponentialBackoff{minBackoff, maxBackoff}
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type exponentialBackoff struct {
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min, max time.Duration
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}
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// delay calculates the delay that should happen at n-th
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// exponential backoff in a series.
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func (b exponentialBackoff) delay(retries int) time.Duration {
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min, max := float64(b.min), float64(b.max)
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delay := min
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for delay < max && retries > 0 {
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delay *= rate
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retries--
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}
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if delay > max {
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delay = max
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}
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delay -= delay * jitter * rand.Float64()
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if delay < min {
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delay = min
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}
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return time.Duration(delay)
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}
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