86 lines
2.2 KiB
Go
86 lines
2.2 KiB
Go
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/*
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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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"sync"
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"time"
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"github.com/golang/groupcache/lru"
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)
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// Clock defines an interface for obtaining the current time
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type Clock interface {
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Now() time.Time
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}
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// realClock implements the Clock interface by calling time.Now()
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type realClock struct{}
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func (realClock) Now() time.Time { return time.Now() }
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type LRUExpireCache struct {
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// clock is used to obtain the current time
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clock Clock
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cache *lru.Cache
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lock sync.Mutex
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}
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// NewLRUExpireCache creates an expiring cache with the given size
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func NewLRUExpireCache(maxSize int) *LRUExpireCache {
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return &LRUExpireCache{clock: realClock{}, cache: lru.New(maxSize)}
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}
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// NewLRUExpireCache creates an expiring cache with the given size, using the specified clock to obtain the current time
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func NewLRUExpireCacheWithClock(maxSize int, clock Clock) *LRUExpireCache {
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return &LRUExpireCache{clock: clock, cache: lru.New(maxSize)}
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}
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type cacheEntry struct {
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value interface{}
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expireTime time.Time
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}
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func (c *LRUExpireCache) Add(key lru.Key, value interface{}, ttl time.Duration) {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.cache.Add(key, &cacheEntry{value, c.clock.Now().Add(ttl)})
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// Remove entry from cache after ttl.
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time.AfterFunc(ttl, func() { c.remove(key) })
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}
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func (c *LRUExpireCache) Get(key lru.Key) (interface{}, bool) {
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c.lock.Lock()
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defer c.lock.Unlock()
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e, ok := c.cache.Get(key)
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if !ok {
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return nil, false
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}
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if c.clock.Now().After(e.(*cacheEntry).expireTime) {
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go c.remove(key)
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return nil, false
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}
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return e.(*cacheEntry).value, true
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}
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func (c *LRUExpireCache) remove(key lru.Key) {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.cache.Remove(key)
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}
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