1 files changed, 307 insertions, 0 deletions
diff --git a/vendor/github.com/ReneKroon/ttlcache/cache.go b/vendor/github.com/ReneKroon/ttlcache/cache.go
new file mode 100644
index 000000000..f772d0c7c
--- /dev/null
+++ b/vendor/github.com/ReneKroon/ttlcache/cache.go
@@ -0,0 +1,307 @@
+package ttlcache
+
+import (
+	"sync"
+	"time"
+)
+
+// CheckExpireCallback is used as a callback for an external check on item expiration
+type checkExpireCallback func(key string, value interface{}) bool
+
+// ExpireCallback is used as a callback on item expiration or when notifying of an item new to the cache
+type expireCallback func(key string, value interface{})
+
+// Cache is a synchronized map of items that can auto-expire once stale
+type Cache struct {
+	mutex                  sync.Mutex
+	ttl                    time.Duration
+	items                  map[string]*item
+	expireCallback         expireCallback
+	checkExpireCallback    checkExpireCallback
+	newItemCallback        expireCallback
+	priorityQueue          *priorityQueue
+	expirationNotification chan bool
+	expirationTime         time.Time
+	skipTTLExtension       bool
+	shutdownSignal         chan (chan struct{})
+	isShutDown             bool
+}
+
+func (cache *Cache) getItem(key string) (*item, bool, bool) {
+	item, exists := cache.items[key]
+	if !exists || item.expired() {
+		return nil, false, false
+	}
+
+	if item.ttl >= 0 && (item.ttl > 0 || cache.ttl > 0) {
+		if cache.ttl > 0 && item.ttl == 0 {
+			item.ttl = cache.ttl
+		}
+
+		if !cache.skipTTLExtension {
+			item.touch()
+		}
+		cache.priorityQueue.update(item)
+	}
+
+	expirationNotification := false
+	if cache.expirationTime.After(time.Now().Add(item.ttl)) {
+		expirationNotification = true
+	}
+	return item, exists, expirationNotification
+}
+
+func (cache *Cache) startExpirationProcessing() {
+	timer := time.NewTimer(time.Hour)
+	for {
+		var sleepTime time.Duration
+		cache.mutex.Lock()
+		if cache.priorityQueue.Len() > 0 {
+			sleepTime = time.Until(cache.priorityQueue.items[0].expireAt)
+			if sleepTime < 0 && cache.priorityQueue.items[0].expireAt.IsZero() {
+				sleepTime = time.Hour
+			} else if sleepTime < 0 {
+				sleepTime = time.Microsecond
+			}
+			if cache.ttl > 0 {
+				sleepTime = min(sleepTime, cache.ttl)
+			}
+
+		} else if cache.ttl > 0 {
+			sleepTime = cache.ttl
+		} else {
+			sleepTime = time.Hour
+		}
+
+		cache.expirationTime = time.Now().Add(sleepTime)
+		cache.mutex.Unlock()
+
+		timer.Reset(sleepTime)
+		select {
+		case shutdownFeedback := <-cache.shutdownSignal:
+			timer.Stop()
+			cache.mutex.Lock()
+			if cache.priorityQueue.Len() > 0 {
+				cache.evictjob()
+			}
+			cache.mutex.Unlock()
+			shutdownFeedback <- struct{}{}
+			return
+		case <-timer.C:
+			timer.Stop()
+			cache.mutex.Lock()
+			if cache.priorityQueue.Len() == 0 {
+				cache.mutex.Unlock()
+				continue
+			}
+
+			cache.cleanjob()
+			cache.mutex.Unlock()
+
+		case <-cache.expirationNotification:
+			timer.Stop()
+			continue
+		}
+	}
+}
+
+func (cache *Cache) evictjob() {
+	// index will only be advanced if the current entry will not be evicted
+	i := 0
+	for item := cache.priorityQueue.items[i]; ; item = cache.priorityQueue.items[i] {
+
+		cache.priorityQueue.remove(item)
+		delete(cache.items, item.key)
+		if cache.expireCallback != nil {
+			go cache.expireCallback(item.key, item.data)
+		}
+		if cache.priorityQueue.Len() == 0 {
+			return
+		}
+	}
+}
+
+func (cache *Cache) cleanjob() {
+	// index will only be advanced if the current entry will not be evicted
+	i := 0
+	for item := cache.priorityQueue.items[i]; item.expired(); item = cache.priorityQueue.items[i] {
+
+		if cache.checkExpireCallback != nil {
+			if !cache.checkExpireCallback(item.key, item.data) {
+				item.touch()
+				cache.priorityQueue.update(item)
+				i++
+				if i == cache.priorityQueue.Len() {
+					break
+				}
+				continue
+			}
+		}
+
+		cache.priorityQueue.remove(item)
+		delete(cache.items, item.key)
+		if cache.expireCallback != nil {
+			go cache.expireCallback(item.key, item.data)
+		}
+		if cache.priorityQueue.Len() == 0 {
+			return
+		}
+	}
+}
+
+// Close calls Purge, and then stops the goroutine that does ttl checking, for a clean shutdown.
+// The cache is no longer cleaning up after the first call to Close, repeated calls are safe though.
+func (cache *Cache) Close() {
+
+	cache.mutex.Lock()
+	if !cache.isShutDown {
+		cache.isShutDown = true
+		cache.mutex.Unlock()
+		feedback := make(chan struct{})
+		cache.shutdownSignal <- feedback
+		<-feedback
+		close(cache.shutdownSignal)
+	} else {
+		cache.mutex.Unlock()
+	}
+	cache.Purge()
+}
+
+// Set is a thread-safe way to add new items to the map
+func (cache *Cache) Set(key string, data interface{}) {
+	cache.SetWithTTL(key, data, ItemExpireWithGlobalTTL)
+}
+
+// SetWithTTL is a thread-safe way to add new items to the map with individual ttl
+func (cache *Cache) SetWithTTL(key string, data interface{}, ttl time.Duration) {
+	cache.mutex.Lock()
+	item, exists, _ := cache.getItem(key)
+
+	if exists {
+		item.data = data
+		item.ttl = ttl
+	} else {
+		item = newItem(key, data, ttl)
+		cache.items[key] = item
+	}
+
+	if item.ttl >= 0 && (item.ttl > 0 || cache.ttl > 0) {
+		if cache.ttl > 0 && item.ttl == 0 {
+			item.ttl = cache.ttl
+		}
+		item.touch()
+	}
+
+	if exists {
+		cache.priorityQueue.update(item)
+	} else {
+		cache.priorityQueue.push(item)
+	}
+
+	cache.mutex.Unlock()
+	if !exists && cache.newItemCallback != nil {
+		cache.newItemCallback(key, data)
+	}
+	cache.expirationNotification <- true
+}
+
+// Get is a thread-safe way to lookup items
+// Every lookup, also touches the item, hence extending it's life
+func (cache *Cache) Get(key string) (interface{}, bool) {
+	cache.mutex.Lock()
+	item, exists, triggerExpirationNotification := cache.getItem(key)
+
+	var dataToReturn interface{}
+	if exists {
+		dataToReturn = item.data
+	}
+	cache.mutex.Unlock()
+	if triggerExpirationNotification {
+		cache.expirationNotification <- true
+	}
+	return dataToReturn, exists
+}
+
+func (cache *Cache) Remove(key string) bool {
+	cache.mutex.Lock()
+	object, exists := cache.items[key]
+	if !exists {
+		cache.mutex.Unlock()
+		return false
+	}
+	delete(cache.items, object.key)
+	cache.priorityQueue.remove(object)
+	cache.mutex.Unlock()
+
+	return true
+}
+
+// Count returns the number of items in the cache
+func (cache *Cache) Count() int {
+	cache.mutex.Lock()
+	length := len(cache.items)
+	cache.mutex.Unlock()
+	return length
+}
+
+func (cache *Cache) SetTTL(ttl time.Duration) {
+	cache.mutex.Lock()
+	cache.ttl = ttl
+	cache.mutex.Unlock()
+	cache.expirationNotification <- true
+}
+
+// SetExpirationCallback sets a callback that will be called when an item expires
+func (cache *Cache) SetExpirationCallback(callback expireCallback) {
+	cache.expireCallback = callback
+}
+
+// SetCheckExpirationCallback sets a callback that will be called when an item is about to expire
+// in order to allow external code to decide whether the item expires or remains for another TTL cycle
+func (cache *Cache) SetCheckExpirationCallback(callback checkExpireCallback) {
+	cache.checkExpireCallback = callback
+}
+
+// SetNewItemCallback sets a callback that will be called when a new item is added to the cache
+func (cache *Cache) SetNewItemCallback(callback expireCallback) {
+	cache.newItemCallback = callback
+}
+
+// SkipTtlExtensionOnHit allows the user to change the cache behaviour. When this flag is set to true it will
+// no longer extend TTL of items when they are retrieved using Get, or when their expiration condition is evaluated
+// using SetCheckExpirationCallback.
+func (cache *Cache) SkipTtlExtensionOnHit(value bool) {
+	cache.skipTTLExtension = value
+}
+
+// Purge will remove all entries
+func (cache *Cache) Purge() {
+	cache.mutex.Lock()
+	cache.items = make(map[string]*item)
+	cache.priorityQueue = newPriorityQueue()
+	cache.mutex.Unlock()
+}
+
+// NewCache is a helper to create instance of the Cache struct
+func NewCache() *Cache {
+
+	shutdownChan := make(chan chan struct{})
+
+	cache := &Cache{
+		items:                  make(map[string]*item),
+		priorityQueue:          newPriorityQueue(),
+		expirationNotification: make(chan bool),
+		expirationTime:         time.Now(),
+		shutdownSignal:         shutdownChan,
+		isShutDown:             false,
+	}
+	go cache.startExpirationProcessing()
+	return cache
+}
+
+func min(duration time.Duration, second time.Duration) time.Duration {
+	if duration < second {
+		return duration
+	}
+	return second
+}