129 lines
3.0 KiB
Go
129 lines
3.0 KiB
Go
/*
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Copyright 2023 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 cacher
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import (
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"context"
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"sync"
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"time"
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"google.golang.org/grpc/metadata"
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utilruntime "k8s.io/apimachinery/pkg/util/runtime"
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"k8s.io/apimachinery/pkg/util/wait"
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"k8s.io/klog/v2"
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"k8s.io/utils/clock"
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)
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const (
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// progressRequestPeriod determines period of requesting progress
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// from etcd when there is a request waiting for watch cache to be fresh.
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progressRequestPeriod = 100 * time.Millisecond
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)
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func newConditionalProgressRequester(requestWatchProgress WatchProgressRequester, clock TickerFactory, contextMetadata metadata.MD) *conditionalProgressRequester {
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pr := &conditionalProgressRequester{
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clock: clock,
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requestWatchProgress: requestWatchProgress,
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contextMetadata: contextMetadata,
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}
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pr.cond = sync.NewCond(pr.mux.RLocker())
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return pr
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}
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type WatchProgressRequester func(ctx context.Context) error
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type TickerFactory interface {
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NewTicker(time.Duration) clock.Ticker
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}
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// conditionalProgressRequester will request progress notification if there
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// is a request waiting for watch cache to be fresh.
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type conditionalProgressRequester struct {
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clock TickerFactory
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requestWatchProgress WatchProgressRequester
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contextMetadata metadata.MD
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mux sync.RWMutex
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cond *sync.Cond
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waiting int
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stopped bool
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}
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func (pr *conditionalProgressRequester) Run(stopCh <-chan struct{}) {
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ctx := wait.ContextForChannel(stopCh)
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if pr.contextMetadata != nil {
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ctx = metadata.NewOutgoingContext(ctx, pr.contextMetadata)
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}
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go func() {
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defer utilruntime.HandleCrash()
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<-stopCh
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pr.mux.Lock()
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defer pr.mux.Unlock()
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pr.stopped = true
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pr.cond.Signal()
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}()
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ticker := pr.clock.NewTicker(progressRequestPeriod)
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defer ticker.Stop()
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for {
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stopped := func() bool {
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pr.mux.RLock()
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defer pr.mux.RUnlock()
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for pr.waiting == 0 && !pr.stopped {
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pr.cond.Wait()
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}
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return pr.stopped
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}()
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if stopped {
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return
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}
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select {
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case <-ticker.C():
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shouldRequest := func() bool {
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pr.mux.RLock()
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defer pr.mux.RUnlock()
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return pr.waiting > 0 && !pr.stopped
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}()
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if !shouldRequest {
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continue
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}
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err := pr.requestWatchProgress(ctx)
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if err != nil {
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klog.V(4).InfoS("Error requesting bookmark", "err", err)
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}
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case <-stopCh:
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return
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}
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}
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}
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func (pr *conditionalProgressRequester) Add() {
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pr.mux.Lock()
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defer pr.mux.Unlock()
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pr.waiting += 1
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pr.cond.Signal()
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}
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func (pr *conditionalProgressRequester) Remove() {
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pr.mux.Lock()
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defer pr.mux.Unlock()
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pr.waiting -= 1
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pr.cond.Signal()
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}
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