Cache file descriptors

Godeps/_workspace/src/github.com/AudriusButkevicius/lfu-go/lfu.go

@@ -1,156 +0,0 @@
-package lfu
-
-import (
-	"container/list"
-	"sync"
-)
-
-type Eviction struct {
-	Key   string
-	Value interface{}
-}
-
-type Cache struct {
-	// If len > UpperBound, cache will automatically evict
-	// down to LowerBound.  If either value is 0, this behavior
-	// is disabled.
-	UpperBound      int
-	LowerBound      int
-	values          map[string]*cacheEntry
-	freqs           *list.List
-	len             int
-	lock            *sync.Mutex
-	EvictionChannel chan<- Eviction
-}
-
-type cacheEntry struct {
-	key      string
-	value    interface{}
-	freqNode *list.Element
-}
-
-type listEntry struct {
-	entries map[*cacheEntry]byte
-	freq    int
-}
-
-func New() *Cache {
-	c := new(Cache)
-	c.values = make(map[string]*cacheEntry)
-	c.freqs = list.New()
-	c.lock = new(sync.Mutex)
-	return c
-}
-
-func (c *Cache) Get(key string) interface{} {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-	if e, ok := c.values[key]; ok {
-		c.increment(e)
-		return e.value
-	}
-	return nil
-}
-
-func (c *Cache) Set(key string, value interface{}) {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-	if e, ok := c.values[key]; ok {
-		// value already exists for key.  overwrite
-		e.value = value
-		c.increment(e)
-	} else {
-		// value doesn't exist.  insert
-		e := new(cacheEntry)
-		e.key = key
-		e.value = value
-		c.values[key] = e
-		c.increment(e)
-		c.len++
-		// bounds mgmt
-		if c.UpperBound > 0 && c.LowerBound > 0 {
-			if c.len > c.UpperBound {
-				c.evict(c.len - c.LowerBound)
-			}
-		}
-	}
-}
-
-func (c *Cache) Len() int {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-	return c.len
-}
-
-func (c *Cache) Evict(count int) int {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-	return c.evict(count)
-}
-
-func (c *Cache) evict(count int) int {
-	// No lock here so it can be called
-	// from within the lock (during Set)
-	var evicted int
-	for i := 0; i < count; {
-		if place := c.freqs.Front(); place != nil {
-			for entry, _ := range place.Value.(*listEntry).entries {
-				if i < count {
-					if c.EvictionChannel != nil {
-						c.EvictionChannel <- Eviction{
-							Key:   entry.key,
-							Value: entry.value,
-						}
-					}
-					delete(c.values, entry.key)
-					c.remEntry(place, entry)
-					evicted++
-					c.len--
-					i++
-				}
-			}
-		}
-	}
-	return evicted
-}
-
-func (c *Cache) increment(e *cacheEntry) {
-	currentPlace := e.freqNode
-	var nextFreq int
-	var nextPlace *list.Element
-	if currentPlace == nil {
-		// new entry
-		nextFreq = 1
-		nextPlace = c.freqs.Front()
-	} else {
-		// move up
-		nextFreq = currentPlace.Value.(*listEntry).freq + 1
-		nextPlace = currentPlace.Next()
-	}
-
-	if nextPlace == nil || nextPlace.Value.(*listEntry).freq != nextFreq {
-		// create a new list entry
-		li := new(listEntry)
-		li.freq = nextFreq
-		li.entries = make(map[*cacheEntry]byte)
-		if currentPlace != nil {
-			nextPlace = c.freqs.InsertAfter(li, currentPlace)
-		} else {
-			nextPlace = c.freqs.PushFront(li)
-		}
-	}
-	e.freqNode = nextPlace
-	nextPlace.Value.(*listEntry).entries[e] = 1
-	if currentPlace != nil {
-		// remove from current position
-		c.remEntry(currentPlace, e)
-	}
-}
-
-func (c *Cache) remEntry(place *list.Element, entry *cacheEntry) {
-	entries := place.Value.(*listEntry).entries
-	delete(entries, entry)
-	if len(entries) == 0 {
-		c.freqs.Remove(place)
-	}
-}