97 lines
2.1 KiB
Go
97 lines
2.1 KiB
Go
/*
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Copyright 2022 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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"fmt"
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"sync"
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)
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type status int
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const (
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Pending status = iota
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Ready
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Stopped
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)
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// ready is a three state condition variable that blocks until is Ready if is not Stopped.
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// Its initial state is Pending.
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type ready struct {
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state status
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c *sync.Cond
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}
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func newReady() *ready {
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return &ready{
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c: sync.NewCond(&sync.RWMutex{}),
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state: Pending,
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}
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}
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// wait blocks until it is Ready or Stopped, it returns an error if is Stopped.
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func (r *ready) wait() error {
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r.c.L.Lock()
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defer r.c.L.Unlock()
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for r.state == Pending {
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r.c.Wait()
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}
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switch r.state {
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case Ready:
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return nil
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case Stopped:
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return fmt.Errorf("apiserver cacher is stopped")
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default:
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return fmt.Errorf("unexpected apiserver cache state: %v", r.state)
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}
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}
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// check returns true only if it is Ready.
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func (r *ready) check() bool {
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// TODO: Make check() function more sophisticated, in particular
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// allow it to behave as "waitWithTimeout".
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rwMutex := r.c.L.(*sync.RWMutex)
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rwMutex.RLock()
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defer rwMutex.RUnlock()
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return r.state == Ready
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}
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// set the state to Pending (false) or Ready (true), it does not have effect if the state is Stopped.
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func (r *ready) set(ok bool) {
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r.c.L.Lock()
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defer r.c.L.Unlock()
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if r.state == Stopped {
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return
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}
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if ok {
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r.state = Ready
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} else {
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r.state = Pending
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}
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r.c.Broadcast()
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}
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// stop the condition variable and set it as Stopped. This state is irreversible.
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func (r *ready) stop() {
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r.c.L.Lock()
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defer r.c.L.Unlock()
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if r.state != Stopped {
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r.state = Stopped
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r.c.Broadcast()
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}
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}
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