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Diffstat (limited to 'vendor/k8s.io/apimachinery/pkg/util/cache/lruexpirecache.go')
-rw-r--r-- | vendor/k8s.io/apimachinery/pkg/util/cache/lruexpirecache.go | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/vendor/k8s.io/apimachinery/pkg/util/cache/lruexpirecache.go b/vendor/k8s.io/apimachinery/pkg/util/cache/lruexpirecache.go new file mode 100644 index 000000000..f6b307aa6 --- /dev/null +++ b/vendor/k8s.io/apimachinery/pkg/util/cache/lruexpirecache.go @@ -0,0 +1,102 @@ +/* +Copyright 2016 The Kubernetes Authors. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +package cache + +import ( + "sync" + "time" + + "github.com/hashicorp/golang-lru" +) + +// Clock defines an interface for obtaining the current time +type Clock interface { + Now() time.Time +} + +// realClock implements the Clock interface by calling time.Now() +type realClock struct{} + +func (realClock) Now() time.Time { return time.Now() } + +// LRUExpireCache is a cache that ensures the mostly recently accessed keys are returned with +// a ttl beyond which keys are forcibly expired. +type LRUExpireCache struct { + // clock is used to obtain the current time + clock Clock + + cache *lru.Cache + lock sync.Mutex +} + +// NewLRUExpireCache creates an expiring cache with the given size +func NewLRUExpireCache(maxSize int) *LRUExpireCache { + return NewLRUExpireCacheWithClock(maxSize, realClock{}) +} + +// NewLRUExpireCacheWithClock creates an expiring cache with the given size, using the specified clock to obtain the current time. +func NewLRUExpireCacheWithClock(maxSize int, clock Clock) *LRUExpireCache { + cache, err := lru.New(maxSize) + if err != nil { + // if called with an invalid size + panic(err) + } + return &LRUExpireCache{clock: clock, cache: cache} +} + +type cacheEntry struct { + value interface{} + expireTime time.Time +} + +// Add adds the value to the cache at key with the specified maximum duration. +func (c *LRUExpireCache) Add(key interface{}, value interface{}, ttl time.Duration) { + c.lock.Lock() + defer c.lock.Unlock() + c.cache.Add(key, &cacheEntry{value, c.clock.Now().Add(ttl)}) +} + +// Get returns the value at the specified key from the cache if it exists and is not +// expired, or returns false. +func (c *LRUExpireCache) Get(key interface{}) (interface{}, bool) { + c.lock.Lock() + defer c.lock.Unlock() + e, ok := c.cache.Get(key) + if !ok { + return nil, false + } + if c.clock.Now().After(e.(*cacheEntry).expireTime) { + c.cache.Remove(key) + return nil, false + } + return e.(*cacheEntry).value, true +} + +// Remove removes the specified key from the cache if it exists +func (c *LRUExpireCache) Remove(key interface{}) { + c.lock.Lock() + defer c.lock.Unlock() + c.cache.Remove(key) +} + +// Keys returns all the keys in the cache, even if they are expired. Subsequent calls to +// get may return not found. It returns all keys from oldest to newest. +func (c *LRUExpireCache) Keys() []interface{} { + c.lock.Lock() + defer c.lock.Unlock() + return c.cache.Keys() +} |