mirror of https://github.com/k3s-io/k3s
108 lines
2.7 KiB
Go
108 lines
2.7 KiB
Go
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/*
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Copyright 2014 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 cache
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import (
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"sync"
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)
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type FIFO struct {
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lock sync.RWMutex
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cond sync.Cond
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items map[string]interface{}
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queue []string
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}
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// Add inserts an item, and puts it in the queue.
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func (f *FIFO) Add(ID string, obj interface{}) {
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f.lock.Lock()
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defer f.lock.Unlock()
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f.items[ID] = obj
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f.queue = append(f.queue, ID)
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f.cond.Broadcast()
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}
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// Update updates an item, and adds it to the queue.
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func (f *FIFO) Update(ID string, obj interface{}) {
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f.lock.Lock()
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defer f.lock.Unlock()
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f.items[ID] = obj
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f.queue = append(f.queue, ID)
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f.cond.Broadcast()
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}
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// Delete removes an item. It doesn't add it to the queue, because
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// this implementation assumes the consumer only cares about the objects,
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// not the order in which they were created/added.
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func (f *FIFO) Delete(ID string, obj interface{}) {
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f.lock.Lock()
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defer f.lock.Unlock()
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delete(f.items, ID)
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}
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// List returns a list of all the items.
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func (f *FIFO) List() []interface{} {
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f.lock.RLock()
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defer f.lock.RUnlock()
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list := make([]interface{}, 0, len(f.items))
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for _, item := range f.items {
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list = append(list, item)
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}
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return list
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}
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// Get returns the requested item, or sets exists=false.
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func (f *FIFO) Get(ID string) (item interface{}, exists bool) {
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f.lock.RLock()
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defer f.lock.RUnlock()
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item, exists = f.items[ID]
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return item, exists
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}
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// Pop waits until an item is ready and returns it. If multiple items are
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// ready, they are returned in the order in which they were added/updated.
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// The item is removed from the queue (and the store) before it is returned,
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// so if you don't succesfully process it, you need to add it back with Add().
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func (f *FIFO) Pop() interface{} {
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f.lock.Lock()
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defer f.lock.Unlock()
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for {
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for len(f.queue) == 0 {
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f.cond.Wait()
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}
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id := f.queue[0]
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f.queue = f.queue[1:]
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item, ok := f.items[id]
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if !ok {
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// Item may have been deleted subsequently.
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continue
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}
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return item
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}
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}
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// NewFIFOStore returns a Store which can be used to queue up items to
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// process.
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func NewFIFOStore() *FIFO {
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f := &FIFO{
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items: map[string]interface{}{},
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queue: []string{},
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}
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f.cond.L = &f.lock
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return f
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}
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