diff options
Diffstat (limited to 'kube2msb/src/kube2msb/vendor/k8s.io/kubernetes/pkg/client/cache/expiration_cache.go')
-rw-r--r-- | kube2msb/src/kube2msb/vendor/k8s.io/kubernetes/pkg/client/cache/expiration_cache.go | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/kube2msb/src/kube2msb/vendor/k8s.io/kubernetes/pkg/client/cache/expiration_cache.go b/kube2msb/src/kube2msb/vendor/k8s.io/kubernetes/pkg/client/cache/expiration_cache.go new file mode 100644 index 0000000..8c5c470 --- /dev/null +++ b/kube2msb/src/kube2msb/vendor/k8s.io/kubernetes/pkg/client/cache/expiration_cache.go @@ -0,0 +1,208 @@ +/* +Copyright 2014 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/golang/glog" + "k8s.io/kubernetes/pkg/util" +) + +// ExpirationCache implements the store interface +// 1. All entries are automatically time stamped on insert +// a. The key is computed based off the original item/keyFunc +// b. The value inserted under that key is the timestamped item +// 2. Expiration happens lazily on read based on the expiration policy +// a. No item can be inserted into the store while we're expiring +// *any* item in the cache. +// 3. Time-stamps are stripped off unexpired entries before return +// Note that the ExpirationCache is inherently slower than a normal +// threadSafeStore because it takes a write lock every time it checks if +// an item has expired. +type ExpirationCache struct { + cacheStorage ThreadSafeStore + keyFunc KeyFunc + clock util.Clock + expirationPolicy ExpirationPolicy + // expirationLock is a write lock used to guarantee that we don't clobber + // newly inserted objects because of a stale expiration timestamp comparison + expirationLock sync.Mutex +} + +// ExpirationPolicy dictates when an object expires. Currently only abstracted out +// so unittests don't rely on the system clock. +type ExpirationPolicy interface { + IsExpired(obj *timestampedEntry) bool +} + +// TTLPolicy implements a ttl based ExpirationPolicy. +type TTLPolicy struct { + // >0: Expire entries with an age > ttl + // <=0: Don't expire any entry + Ttl time.Duration + + // Clock used to calculate ttl expiration + Clock util.Clock +} + +// IsExpired returns true if the given object is older than the ttl, or it can't +// determine its age. +func (p *TTLPolicy) IsExpired(obj *timestampedEntry) bool { + return p.Ttl > 0 && p.Clock.Since(obj.timestamp) > p.Ttl +} + +// timestampedEntry is the only type allowed in a ExpirationCache. +type timestampedEntry struct { + obj interface{} + timestamp time.Time +} + +// getTimestampedEntry returnes the timestampedEntry stored under the given key. +func (c *ExpirationCache) getTimestampedEntry(key string) (*timestampedEntry, bool) { + item, _ := c.cacheStorage.Get(key) + if tsEntry, ok := item.(*timestampedEntry); ok { + return tsEntry, true + } + return nil, false +} + +// getOrExpire retrieves the object from the timestampedEntry if and only if it hasn't +// already expired. It holds a write lock across deletion. +func (c *ExpirationCache) getOrExpire(key string) (interface{}, bool) { + // Prevent all inserts from the time we deem an item as "expired" to when we + // delete it, so an un-expired item doesn't sneak in under the same key, just + // before the Delete. + c.expirationLock.Lock() + defer c.expirationLock.Unlock() + timestampedItem, exists := c.getTimestampedEntry(key) + if !exists { + return nil, false + } + if c.expirationPolicy.IsExpired(timestampedItem) { + glog.V(4).Infof("Entry %v: %+v has expired", key, timestampedItem.obj) + c.cacheStorage.Delete(key) + return nil, false + } + return timestampedItem.obj, true +} + +// GetByKey returns the item stored under the key, or sets exists=false. +func (c *ExpirationCache) GetByKey(key string) (interface{}, bool, error) { + obj, exists := c.getOrExpire(key) + return obj, exists, nil +} + +// Get returns unexpired items. It purges the cache of expired items in the +// process. +func (c *ExpirationCache) Get(obj interface{}) (interface{}, bool, error) { + key, err := c.keyFunc(obj) + if err != nil { + return nil, false, KeyError{obj, err} + } + obj, exists := c.getOrExpire(key) + return obj, exists, nil +} + +// List retrieves a list of unexpired items. It purges the cache of expired +// items in the process. +func (c *ExpirationCache) List() []interface{} { + items := c.cacheStorage.List() + + list := make([]interface{}, 0, len(items)) + for _, item := range items { + obj := item.(*timestampedEntry).obj + if key, err := c.keyFunc(obj); err != nil { + list = append(list, obj) + } else if obj, exists := c.getOrExpire(key); exists { + list = append(list, obj) + } + } + return list +} + +// ListKeys returns a list of all keys in the expiration cache. +func (c *ExpirationCache) ListKeys() []string { + return c.cacheStorage.ListKeys() +} + +// Add timestamps an item and inserts it into the cache, overwriting entries +// that might exist under the same key. +func (c *ExpirationCache) Add(obj interface{}) error { + c.expirationLock.Lock() + defer c.expirationLock.Unlock() + + key, err := c.keyFunc(obj) + if err != nil { + return KeyError{obj, err} + } + c.cacheStorage.Add(key, ×tampedEntry{obj, c.clock.Now()}) + return nil +} + +// Update has not been implemented yet for lack of a use case, so this method +// simply calls `Add`. This effectively refreshes the timestamp. +func (c *ExpirationCache) Update(obj interface{}) error { + return c.Add(obj) +} + +// Delete removes an item from the cache. +func (c *ExpirationCache) Delete(obj interface{}) error { + c.expirationLock.Lock() + defer c.expirationLock.Unlock() + key, err := c.keyFunc(obj) + if err != nil { + return KeyError{obj, err} + } + c.cacheStorage.Delete(key) + return nil +} + +// Replace will convert all items in the given list to TimestampedEntries +// before attempting the replace operation. The replace operation will +// delete the contents of the ExpirationCache `c`. +func (c *ExpirationCache) Replace(list []interface{}, resourceVersion string) error { + c.expirationLock.Lock() + defer c.expirationLock.Unlock() + items := map[string]interface{}{} + ts := c.clock.Now() + for _, item := range list { + key, err := c.keyFunc(item) + if err != nil { + return KeyError{item, err} + } + items[key] = ×tampedEntry{item, ts} + } + c.cacheStorage.Replace(items, resourceVersion) + return nil +} + +// Resync will touch all objects to put them into the processing queue +func (c *ExpirationCache) Resync() error { + return c.cacheStorage.Resync() +} + +// NewTTLStore creates and returns a ExpirationCache with a TTLPolicy +func NewTTLStore(keyFunc KeyFunc, ttl time.Duration) Store { + return &ExpirationCache{ + cacheStorage: NewThreadSafeStore(Indexers{}, Indices{}), + keyFunc: keyFunc, + clock: util.RealClock{}, + expirationPolicy: &TTLPolicy{ttl, util.RealClock{}}, + } +} |