mirror of https://github.com/status-im/consul.git
108 lines
3.4 KiB
Go
108 lines
3.4 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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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 rest
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import (
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"net/url"
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"time"
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"github.com/golang/glog"
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"k8s.io/apimachinery/pkg/util/sets"
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"k8s.io/client-go/util/flowcontrol"
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)
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// Set of resp. Codes that we backoff for.
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// In general these should be errors that indicate a server is overloaded.
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// These shouldn't be configured by any user, we set them based on conventions
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// described in
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var serverIsOverloadedSet = sets.NewInt(429)
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var maxResponseCode = 499
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type BackoffManager interface {
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UpdateBackoff(actualUrl *url.URL, err error, responseCode int)
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CalculateBackoff(actualUrl *url.URL) time.Duration
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Sleep(d time.Duration)
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}
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// URLBackoff struct implements the semantics on top of Backoff which
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// we need for URL specific exponential backoff.
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type URLBackoff struct {
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// Uses backoff as underlying implementation.
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Backoff *flowcontrol.Backoff
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}
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// NoBackoff is a stub implementation, can be used for mocking or else as a default.
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type NoBackoff struct {
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}
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func (n *NoBackoff) UpdateBackoff(actualUrl *url.URL, err error, responseCode int) {
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// do nothing.
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}
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func (n *NoBackoff) CalculateBackoff(actualUrl *url.URL) time.Duration {
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return 0 * time.Second
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}
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func (n *NoBackoff) Sleep(d time.Duration) {
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time.Sleep(d)
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}
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// Disable makes the backoff trivial, i.e., sets it to zero. This might be used
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// by tests which want to run 1000s of mock requests without slowing down.
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func (b *URLBackoff) Disable() {
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glog.V(4).Infof("Disabling backoff strategy")
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b.Backoff = flowcontrol.NewBackOff(0*time.Second, 0*time.Second)
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}
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// baseUrlKey returns the key which urls will be mapped to.
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// For example, 127.0.0.1:8080/api/v2/abcde -> 127.0.0.1:8080.
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func (b *URLBackoff) baseUrlKey(rawurl *url.URL) string {
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// Simple implementation for now, just the host.
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// We may backoff specific paths (i.e. "pods") differentially
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// in the future.
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host, err := url.Parse(rawurl.String())
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if err != nil {
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glog.V(4).Infof("Error extracting url: %v", rawurl)
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panic("bad url!")
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}
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return host.Host
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}
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// UpdateBackoff updates backoff metadata
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func (b *URLBackoff) UpdateBackoff(actualUrl *url.URL, err error, responseCode int) {
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// range for retry counts that we store is [0,13]
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if responseCode > maxResponseCode || serverIsOverloadedSet.Has(responseCode) {
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b.Backoff.Next(b.baseUrlKey(actualUrl), b.Backoff.Clock.Now())
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return
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} else if responseCode >= 300 || err != nil {
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glog.V(4).Infof("Client is returning errors: code %v, error %v", responseCode, err)
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}
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//If we got this far, there is no backoff required for this URL anymore.
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b.Backoff.Reset(b.baseUrlKey(actualUrl))
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}
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// CalculateBackoff takes a url and back's off exponentially,
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// based on its knowledge of existing failures.
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func (b *URLBackoff) CalculateBackoff(actualUrl *url.URL) time.Duration {
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return b.Backoff.Get(b.baseUrlKey(actualUrl))
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}
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func (b *URLBackoff) Sleep(d time.Duration) {
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b.Backoff.Clock.Sleep(d)
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}
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