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119 lines
3.3 KiB
119 lines
3.3 KiB
/*
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* Copyright 2017 Baidu, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. 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 distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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* either express or implied. See the License for the specific language governing permissions
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* and limitations under the License.
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*/
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// retry.go - define the retry policy when making requests to BCE services
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package bce
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import (
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"net"
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"net/http"
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"time"
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"github.com/baidubce/bce-sdk-go/util/log"
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)
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// RetryPolicy defines the two methods to retry for sending request.
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type RetryPolicy interface {
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ShouldRetry(BceError, int) bool
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GetDelayBeforeNextRetryInMillis(BceError, int) time.Duration
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}
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// NoRetryPolicy just does not retry.
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type NoRetryPolicy struct{}
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func (_ *NoRetryPolicy) ShouldRetry(err BceError, attempts int) bool {
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return false
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}
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func (_ *NoRetryPolicy) GetDelayBeforeNextRetryInMillis(
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err BceError, attempts int) time.Duration {
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return 0 * time.Millisecond
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}
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func NewNoRetryPolicy() *NoRetryPolicy {
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return &NoRetryPolicy{}
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}
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// BackOffRetryPolicy implements a policy that retries with exponential back-off strategy.
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// This policy will keep retrying until the maximum number of retries is reached. The delay time
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// will be a fixed interval for the first time then 2 * interval for the second, 4 * internal for
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// the third, and so on.
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// In general, the delay time will be 2^number_of_retries_attempted*interval. When a maximum of
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// delay time is specified, the delay time will never exceed this limit.
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type BackOffRetryPolicy struct {
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maxErrorRetry int
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maxDelayInMillis int64
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baseIntervalInMillis int64
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}
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func (b *BackOffRetryPolicy) ShouldRetry(err BceError, attempts int) bool {
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// Do not retry any more when retry the max times
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if attempts >= b.maxErrorRetry {
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return false
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}
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if err == nil {
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return true
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}
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// Always retry on IO error
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if _, ok := err.(net.Error); ok {
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return true
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}
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// Only retry on a service error
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if realErr, ok := err.(*BceServiceError); ok {
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switch realErr.StatusCode {
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case http.StatusInternalServerError:
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log.Warn("retry for internal server error(500)")
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return true
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case http.StatusBadGateway:
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log.Warn("retry for bad gateway(502)")
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return true
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case http.StatusServiceUnavailable:
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log.Warn("retry for service unavailable(503)")
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return true
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case http.StatusBadRequest:
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if realErr.Code != "Http400" {
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return false
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}
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log.Warn("retry for bad request(400)")
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return true
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}
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if realErr.Code == EREQUEST_EXPIRED {
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log.Warn("retry for request expired")
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return true
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}
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}
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return false
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}
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func (b *BackOffRetryPolicy) GetDelayBeforeNextRetryInMillis(
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err BceError, attempts int) time.Duration {
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if attempts < 0 {
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return 0 * time.Millisecond
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}
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delayInMillis := (1 << uint64(attempts)) * b.baseIntervalInMillis
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if delayInMillis > b.maxDelayInMillis {
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return time.Duration(b.maxDelayInMillis) * time.Millisecond
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}
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return time.Duration(delayInMillis) * time.Millisecond
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}
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func NewBackOffRetryPolicy(maxRetry int, maxDelay, base int64) *BackOffRetryPolicy {
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return &BackOffRetryPolicy{maxRetry, maxDelay, base}
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}
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