Improve(fakeip): use lru cache to avoid outdate

common/cache/lrucache.go

@@ -0,0 +1,148 @@
+package cache
+
+// Modified by https://github.com/die-net/lrucache
+
+import (
+	"container/list"
+	"sync"
+	"time"
+)
+
+// Option is part of Functional Options Pattern
+type Option func(*LruCache)
+
+// WithUpdateAgeOnGet update expires when Get element
+func WithUpdateAgeOnGet() Option {
+	return func(l *LruCache) {
+		l.updateAgeOnGet = true
+	}
+}
+
+// WithAge defined element max age (second)
+func WithAge(maxAge int64) Option {
+	return func(l *LruCache) {
+		l.maxAge = maxAge
+	}
+}
+
+// WithSize defined max length of LruCache
+func WithSize(maxSize int) Option {
+	return func(l *LruCache) {
+		l.maxSize = maxSize
+	}
+}
+
+// LruCache is a thread-safe, in-memory lru-cache that evicts the
+// least recently used entries from memory when (if set) the entries are
+// older than maxAge (in seconds).  Use the New constructor to create one.
+type LruCache struct {
+	maxAge         int64
+	maxSize        int
+	mu             sync.Mutex
+	cache          map[interface{}]*list.Element
+	lru            *list.List // Front is least-recent
+	updateAgeOnGet bool
+}
+
+// NewLRUCache creates an LruCache
+func NewLRUCache(options ...Option) *LruCache {
+	lc := &LruCache{
+		lru:   list.New(),
+		cache: make(map[interface{}]*list.Element),
+	}
+
+	for _, option := range options {
+		option(lc)
+	}
+
+	return lc
+}
+
+// Get returns the interface{} representation of a cached response and a bool
+// set to true if the key was found.
+func (c *LruCache) Get(key interface{}) (interface{}, bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	le, ok := c.cache[key]
+	if !ok {
+		return nil, false
+	}
+
+	if c.maxAge > 0 && le.Value.(*entry).expires <= time.Now().Unix() {
+		c.deleteElement(le)
+		c.maybeDeleteOldest()
+
+		return nil, false
+	}
+
+	c.lru.MoveToBack(le)
+	entry := le.Value.(*entry)
+	if c.maxAge > 0 && c.updateAgeOnGet {
+		entry.expires = time.Now().Unix() + c.maxAge
+	}
+	value := entry.value
+
+	return value, true
+}
+
+// Set stores the interface{} representation of a response for a given key.
+func (c *LruCache) Set(key interface{}, value interface{}) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	expires := int64(0)
+	if c.maxAge > 0 {
+		expires = time.Now().Unix() + c.maxAge
+	}
+
+	if le, ok := c.cache[key]; ok {
+		c.lru.MoveToBack(le)
+		e := le.Value.(*entry)
+		e.value = value
+		e.expires = expires
+	} else {
+		e := &entry{key: key, value: value, expires: expires}
+		c.cache[key] = c.lru.PushBack(e)
+
+		if c.maxSize > 0 {
+			if len := c.lru.Len(); len > c.maxSize {
+				c.deleteElement(c.lru.Front())
+			}
+		}
+	}
+
+	c.maybeDeleteOldest()
+}
+
+// Delete removes the value associated with a key.
+func (c *LruCache) Delete(key string) {
+	c.mu.Lock()
+
+	if le, ok := c.cache[key]; ok {
+		c.deleteElement(le)
+	}
+
+	c.mu.Unlock()
+}
+
+func (c *LruCache) maybeDeleteOldest() {
+	if c.maxAge > 0 {
+		now := time.Now().Unix()
+		for le := c.lru.Front(); le != nil && le.Value.(*entry).expires <= now; le = c.lru.Front() {
+			c.deleteElement(le)
+		}
+	}
+}
+
+func (c *LruCache) deleteElement(le *list.Element) {
+	c.lru.Remove(le)
+	e := le.Value.(*entry)
+	delete(c.cache, e.key)
+}
+
+type entry struct {
+	key     interface{}
+	value   interface{}
+	expires int64
+}