change map to binary tree

cache.go

@@ -59,6 +59,9 @@ type unexportedInterface interface {
 }
 
 type Item struct {
+	Right      *Item
+	Left       *Item
+	Key        string
 	Object     interface{}
 	Expiration *time.Time
 }
@@ -68,7 +71,177 @@ func (item *Item) Expired() bool {
 	if item.Expiration == nil {
 		return false
 	}
-	return item.Expiration.Before(time.Now())
+	return time.Now().UnixNano() > item.Expiration.UnixNano()
+}
+
+func (item *Item) add(key string, object interface{}, expiration *time.Time) {
+	if item.Key == key {
+		item.Expiration = expiration
+		return
+	}
+	if item.Key == "" {
+		item.Key = key
+		item.Object = object
+		item.Expiration = expiration
+		return
+	}
+	if item.Key < key {
+		if item.Left == nil {
+			item.Left = new(Item)
+		}
+		item.Left.add(key, object, expiration)
+		return
+	}
+	if item.Key > key {
+		if item.Right == nil {
+			item.Right = new(Item)
+		}
+		item.Right.add(key, object, expiration)
+		return
+	}
+}
+
+func (item *Item) copy(res *Item) {
+	item.Right = res.Right
+	item.Left = res.Left
+	item.Key = res.Key
+	item.Object = res.Object
+	item.Expiration = res.Expiration
+}
+
+func (item *Item) addItem(res *Item) {
+	if res == nil {
+		return
+	}
+	if item.Object == nil {
+		item.copy(res)
+		return
+	}
+	if item.Key == res.Key {
+		item.copy(res)
+	}
+	if item.Key < res.Key {
+		item.Left.addItem(res)
+		return
+	}
+	if item.Key > res.Key {
+		item.Right.addItem(res)
+		return
+	}
+}
+
+func (item *Item) delExpirie() {
+	if item.Left != nil {
+		item.Left.delExpirie()
+	}
+	if item.Expired() {
+		newItem := new(Item)
+		newItem.addItem(item.Left)
+		newItem.addItem(item.Right)
+		item.copy(newItem)
+		item = newItem
+	}
+	if item.Right != nil {
+		item.Right.delExpirie()
+	}
+}
+
+func (item *Item) get(key string) (res *Item, found bool) {
+	if item == nil {
+		return res, false
+	}
+	if item.Key == key {
+		return item, true
+	}
+	if item.Key < key {
+		return item.Left.get(key)
+	}
+	if item.Key > key {
+		return item.Right.get(key)
+	}
+	return item, found
+}
+
+func (item *Item) set(key string, obj interface{}) {
+	if item == nil {
+		return
+	}
+	if item.Key == key {
+		item.Object = obj
+		return
+	}
+	if item.Key < key {
+		if item.Left != nil {
+			item.Left.set(key, obj)
+			return
+		}
+	}
+	if item.Key > key {
+		if item.Right != nil {
+			item.Right.set(key, obj)
+			return
+		}
+	}
+}
+
+func (item *Item) del(key string) {
+	res, found := item.get(key)
+	if found {
+		item.Key = ""
+		item.Object = nil
+		item.Expiration = nil
+		if res.Right != nil {
+			item.addItem(res.Right)
+			item.Right = nil
+		}
+		if res.Left != nil {
+			item.addItem(res.Left)
+			item.Left = nil
+		}
+		res = nil
+	}
+}
+
+func (item *Item) rangeFunc(body func(*Item)) {
+	if item.Left != nil {
+		item.Left.rangeFunc(body)
+	}
+	body(item)
+	if item.Right != nil {
+		item.Right.rangeFunc(body)
+	}
+}
+
+func (item *Item) len() (count int) {
+	if item.Left != nil {
+		count = item.Left.len()
+	}
+	count++
+	if item.Right != nil {
+		count += item.Right.len()
+	}
+	return count
+}
+
+func (item *Item) toSlice() (items []Item) {
+	if item.Left != nil {
+		items = append(items, item.Left.toSlice()...)
+	}
+	items = append(items, Item{
+		Key:        item.Key,
+		Object:     item.Object,
+		Expiration: item.Expiration,
+	})
+	if item.Right != nil {
+		items = append(items, item.Right.toSlice()...)
+	}
+	return items
+}
+
+func (item *Item) fromSlice(items []Item) {
+	for _, i := range items {
+		item.add(i.Key, i.Object, i.Expiration)
+	}
 }
 
 type Cache struct {
@@ -79,7 +252,7 @@ type Cache struct {
 type cache struct {
 	sync.RWMutex
 	defaultExpiration time.Duration
-	items             map[string]*Item
+	items             *Item //map[string]*Item
 	janitor           *janitor
 }
 
@@ -103,10 +276,13 @@ func (c *cache) set(k string, x interface{}, d time.Duration) {
 		t := time.Now().Add(d)
 		e = &t
 	}
+	c.items.add(k, x, e)
+	/*
 		c.items[k] = &Item{
 			Object:     x,
 			Expiration: e,
 		}
+	*/
 }
 
 // Add an item to the cache only if an item doesn't already exist for the given
@@ -147,7 +323,7 @@ func (c *cache) Get(k string) (interface{}, bool) {
 }
 
 func (c *cache) get(k string) (interface{}, bool) {
-	item, found := c.items[k]
+	item, found := c.items.get(k)
 	if !found || item.Expired() {
 		return nil, false
 	}
@@ -161,7 +337,7 @@ func (c *cache) get(k string) (interface{}, bool) {
 // of the specialized methods, e.g. IncrementInt64.
 func (c *cache) Increment(k string, n int64) error {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return fmt.Errorf("Item %s not found", k)
@@ -208,7 +384,7 @@ func (c *cache) Increment(k string, n int64) error {
 // e.g. IncrementFloat64.
 func (c *cache) IncrementFloat(k string, n float64) error {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return fmt.Errorf("Item %s not found", k)
@@ -231,7 +407,7 @@ func (c *cache) IncrementFloat(k string, n float64) error {
 // value is returned.
 func (c *cache) IncrementInt(k string, n int) (int, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -252,7 +428,7 @@ func (c *cache) IncrementInt(k string, n int) (int, error) {
 // value is returned.
 func (c *cache) IncrementInt8(k string, n int8) (int8, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -273,7 +449,7 @@ func (c *cache) IncrementInt8(k string, n int8) (int8, error) {
 // value is returned.
 func (c *cache) IncrementInt16(k string, n int16) (int16, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -294,7 +470,7 @@ func (c *cache) IncrementInt16(k string, n int16) (int16, error) {
 // value is returned.
 func (c *cache) IncrementInt32(k string, n int32) (int32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -315,7 +491,7 @@ func (c *cache) IncrementInt32(k string, n int32) (int32, error) {
 // value is returned.
 func (c *cache) IncrementInt64(k string, n int64) (int64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -336,7 +512,7 @@ func (c *cache) IncrementInt64(k string, n int64) (int64, error) {
 // value is returned.
 func (c *cache) IncrementUint(k string, n uint) (uint, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -357,7 +533,7 @@ func (c *cache) IncrementUint(k string, n uint) (uint, error) {
 // incremented value is returned.
 func (c *cache) IncrementUintptr(k string, n uintptr) (uintptr, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -378,7 +554,7 @@ func (c *cache) IncrementUintptr(k string, n uintptr) (uintptr, error) {
 // incremented value is returned.
 func (c *cache) IncrementUint8(k string, n uint8) (uint8, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -399,7 +575,7 @@ func (c *cache) IncrementUint8(k string, n uint8) (uint8, error) {
 // incremented value is returned.
 func (c *cache) IncrementUint16(k string, n uint16) (uint16, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -420,7 +596,7 @@ func (c *cache) IncrementUint16(k string, n uint16) (uint16, error) {
 // incremented value is returned.
 func (c *cache) IncrementUint32(k string, n uint32) (uint32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -441,7 +617,7 @@ func (c *cache) IncrementUint32(k string, n uint32) (uint32, error) {
 // incremented value is returned.
 func (c *cache) IncrementUint64(k string, n uint64) (uint64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -462,7 +638,7 @@ func (c *cache) IncrementUint64(k string, n uint64) (uint64, error) {
 // incremented value is returned.
 func (c *cache) IncrementFloat32(k string, n float32) (float32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -483,7 +659,7 @@ func (c *cache) IncrementFloat32(k string, n float32) (float32, error) {
 // incremented value is returned.
 func (c *cache) IncrementFloat64(k string, n float64) (float64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -508,7 +684,7 @@ func (c *cache) Decrement(k string, n int64) error {
 	// TODO: Implement Increment and Decrement more cleanly.
 	// (Cannot do Increment(k, n*-1) for uints.)
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return fmt.Errorf("Item not found")
@@ -555,7 +731,7 @@ func (c *cache) Decrement(k string, n int64) error {
 // e.g. DecrementFloat64.
 func (c *cache) DecrementFloat(k string, n float64) error {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return fmt.Errorf("Item %s not found", k)
@@ -578,7 +754,7 @@ func (c *cache) DecrementFloat(k string, n float64) error {
 // value is returned.
 func (c *cache) DecrementInt(k string, n int) (int, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -599,7 +775,7 @@ func (c *cache) DecrementInt(k string, n int) (int, error) {
 // value is returned.
 func (c *cache) DecrementInt8(k string, n int8) (int8, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -620,7 +796,7 @@ func (c *cache) DecrementInt8(k string, n int8) (int8, error) {
 // value is returned.
 func (c *cache) DecrementInt16(k string, n int16) (int16, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -641,7 +817,7 @@ func (c *cache) DecrementInt16(k string, n int16) (int16, error) {
 // value is returned.
 func (c *cache) DecrementInt32(k string, n int32) (int32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -662,7 +838,7 @@ func (c *cache) DecrementInt32(k string, n int32) (int32, error) {
 // value is returned.
 func (c *cache) DecrementInt64(k string, n int64) (int64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -683,7 +859,7 @@ func (c *cache) DecrementInt64(k string, n int64) (int64, error) {
 // value is returned.
 func (c *cache) DecrementUint(k string, n uint) (uint, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -704,7 +880,7 @@ func (c *cache) DecrementUint(k string, n uint) (uint, error) {
 // decremented value is returned.
 func (c *cache) DecrementUintptr(k string, n uintptr) (uintptr, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -725,7 +901,7 @@ func (c *cache) DecrementUintptr(k string, n uintptr) (uintptr, error) {
 // value is returned.
 func (c *cache) DecrementUint8(k string, n uint8) (uint8, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -746,7 +922,7 @@ func (c *cache) DecrementUint8(k string, n uint8) (uint8, error) {
 // decremented value is returned.
 func (c *cache) DecrementUint16(k string, n uint16) (uint16, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -767,7 +943,7 @@ func (c *cache) DecrementUint16(k string, n uint16) (uint16, error) {
 // decremented value is returned.
 func (c *cache) DecrementUint32(k string, n uint32) (uint32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -788,7 +964,7 @@ func (c *cache) DecrementUint32(k string, n uint32) (uint32, error) {
 // decremented value is returned.
 func (c *cache) DecrementUint64(k string, n uint64) (uint64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -809,7 +985,7 @@ func (c *cache) DecrementUint64(k string, n uint64) (uint64, error) {
 // decremented value is returned.
 func (c *cache) DecrementFloat32(k string, n float32) (float32, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -830,7 +1006,7 @@ func (c *cache) DecrementFloat32(k string, n float32) (float32, error) {
 // decremented value is returned.
 func (c *cache) DecrementFloat64(k string, n float64) (float64, error) {
 	c.Lock()
-	v, found := c.items[k]
+	v, found := c.items.get(k)
 	if !found || v.Expired() {
 		c.Unlock()
 		return 0, fmt.Errorf("Item %s not found", k)
@@ -854,17 +1030,13 @@ func (c *cache) Delete(k string) {
 }
 
 func (c *cache) delete(k string) {
-	delete(c.items, k)
+	c.items.del(k)
 }
 
 // Delete all expired items from the cache.
 func (c *cache) DeleteExpired() {
 	c.Lock()
-	for k, v := range c.items {
+	c.items.delExpirie()
-		if v.Expired() {
-			c.delete(k)
-		}
-	}
 	c.Unlock()
 }
 
@@ -878,10 +1050,14 @@ func (c *cache) Save(w io.Writer) (err error) {
 	}()
 	c.RLock()
 	defer c.RUnlock()
-	for _, v := range c.items {
+	//.items = new(Item)
-		gob.Register(v.Object)
+	itemSlice := c.items.toSlice()
+	for _, item := range itemSlice {
+		if item.Object != nil {
+			gob.Register(item.Object)
 		}
-	err = enc.Encode(&c.items)
+	}
+	err = enc.Encode(itemSlice)
 	return
 }
 
@@ -904,16 +1080,13 @@ func (c *cache) SaveFile(fname string) error {
 // keys that already exist (and haven't expired) in the current cache.
 func (c *cache) Load(r io.Reader) error {
 	dec := gob.NewDecoder(r)
-	items := map[string]*Item{}
+	var itemSlice []Item
-	err := dec.Decode(&items)
+	err := dec.Decode(&itemSlice)
 	if err == nil {
 		c.Lock()
 		defer c.Unlock()
-		for k, v := range items {
+		for _, item := range itemSlice {
-			ov, found := c.items[k]
+			c.items.add(item.Key, item.Object, item.Expiration)
-			if !found || ov.Expired() {
-				c.items[k] = v
-			}
 		}
 	}
 	return err
@@ -939,7 +1112,7 @@ func (c *cache) LoadFile(fname string) error {
 // fields of the items should be checked. Note that explicit synchronization
 // is needed to use a cache and its corresponding Items() return value at
 // the same time, as the map is shared.
-func (c *cache) Items() map[string]*Item {
+func (c *cache) Items() *Item {
 	c.RLock()
 	defer c.RUnlock()
 	return c.items
@@ -949,7 +1122,7 @@ func (c *cache) Items() map[string]*Item {
 // expired, but have not yet been cleaned up. Equivalent to len(c.Items()).
 func (c *cache) ItemCount() int {
 	c.RLock()
-	n := len(c.items)
+	n := c.items.len()
 	c.RUnlock()
 	return n
 }
@@ -957,7 +1130,7 @@ func (c *cache) ItemCount() int {
 // Delete all items from the cache.
 func (c *cache) Flush() {
 	c.Lock()
-	c.items = map[string]*Item{}
+	c.items = new(Item)
 	c.Unlock()
 }
 
@@ -997,7 +1170,7 @@ func newCache(de time.Duration) *cache {
 	}
 	c := &cache{
 		defaultExpiration: de,
-		items:             map[string]*Item{},
+		items:             new(Item),
 	}
 	return c
 }
@@ -1121,7 +1294,7 @@ func newShardedCache(n int, de time.Duration) *shardedCache {
 	for i := 0; i < n; i++ {
 		c := &cache{
 			defaultExpiration: de,
-			items:             map[string]*Item{},
+			items:             new(Item),
 		}
 		sc.cs[i] = c
 	}

cache_test.go

@@ -1246,7 +1246,6 @@ func testFillAndSerialize(t *testing.T, tc *Cache) {
 	if a.(string) != "a" {
 		t.Error("a is not a")
 	}
-
 	b, found := oc.Get("b")
 	if !found {
 		t.Error("b was not found")