mirror of https://github.com/k3s-io/k3s
85 lines
2.0 KiB
Go
85 lines
2.0 KiB
Go
/*
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Copyright 2016 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 cache
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import (
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"time"
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expirationcache "k8s.io/client-go/tools/cache"
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)
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// ObjectCache is a simple wrapper of expiration cache that
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// 1. use string type key
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// 2. has an updater to get value directly if it is expired
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// 3. then update the cache
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type ObjectCache struct {
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cache expirationcache.Store
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updater func() (interface{}, error)
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}
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// objectEntry is an object with string type key.
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type objectEntry struct {
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key string
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obj interface{}
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}
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// NewObjectCache creates ObjectCache with an updater.
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// updater returns an object to cache.
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func NewObjectCache(f func() (interface{}, error), ttl time.Duration) *ObjectCache {
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return &ObjectCache{
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updater: f,
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cache: expirationcache.NewTTLStore(stringKeyFunc, ttl),
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}
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}
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// stringKeyFunc is a string as cache key function
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func stringKeyFunc(obj interface{}) (string, error) {
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key := obj.(objectEntry).key
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return key, nil
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}
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// Get gets cached objectEntry by using a unique string as the key.
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func (c *ObjectCache) Get(key string) (interface{}, error) {
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value, ok, err := c.cache.Get(objectEntry{key: key})
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if err != nil {
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return nil, err
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}
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if !ok {
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obj, err := c.updater()
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if err != nil {
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return nil, err
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}
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err = c.cache.Add(objectEntry{
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key: key,
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obj: obj,
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})
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if err != nil {
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return nil, err
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}
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return obj, nil
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}
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return value.(objectEntry).obj, nil
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}
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func (c *ObjectCache) Add(key string, obj interface{}) error {
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err := c.cache.Add(objectEntry{key: key, obj: obj})
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if err != nil {
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return err
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}
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return nil
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}
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