use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/hashicorp/golang-lru/lru.go

@@ -1,3 +1,6 @@
+// This package provides a simple LRU cache. It is based on the
+// LRU implementation in groupcache:
+// https://github.com/golang/groupcache/tree/master/lru
 package lru
 
 import (
@@ -8,11 +11,11 @@ import (
 
 // Cache is a thread-safe fixed size LRU cache.
 type Cache struct {
-	lru  simplelru.LRUCache
+	lru  *simplelru.LRU
 	lock sync.RWMutex
 }
 
-// New creates an LRU of the given size.
+// New creates an LRU of the given size
 func New(size int) (*Cache, error) {
 	return NewWithEvict(size, nil)
 }
@@ -30,7 +33,7 @@ func NewWithEvict(size int, onEvicted func(key interface{}, value interface{}))
 	return c, nil
 }
 
-// Purge is used to completely clear the cache.
+// Purge is used to completely clear the cache
 func (c *Cache) Purge() {
 	c.lock.Lock()
 	c.lru.Purge()
@@ -38,51 +41,48 @@ func (c *Cache) Purge() {
 }
 
 // Add adds a value to the cache.  Returns true if an eviction occurred.
-func (c *Cache) Add(key, value interface{}) (evicted bool) {
+func (c *Cache) Add(key, value interface{}) bool {
 	c.lock.Lock()
-	evicted = c.lru.Add(key, value)
-	c.lock.Unlock()
-	return evicted
+	defer c.lock.Unlock()
+	return c.lru.Add(key, value)
 }
 
 // Get looks up a key's value from the cache.
-func (c *Cache) Get(key interface{}) (value interface{}, ok bool) {
+func (c *Cache) Get(key interface{}) (interface{}, bool) {
 	c.lock.Lock()
-	value, ok = c.lru.Get(key)
-	c.lock.Unlock()
-	return value, ok
+	defer c.lock.Unlock()
+	return c.lru.Get(key)
 }
 
-// Contains checks if a key is in the cache, without updating the
-// recent-ness or deleting it for being stale.
+// Check if a key is in the cache, without updating the recent-ness
+// or deleting it for being stale.
 func (c *Cache) Contains(key interface{}) bool {
 	c.lock.RLock()
-	containKey := c.lru.Contains(key)
-	c.lock.RUnlock()
-	return containKey
+	defer c.lock.RUnlock()
+	return c.lru.Contains(key)
 }
 
-// Peek returns the key value (or undefined if not found) without updating
+// Returns the key value (or undefined if not found) without updating
 // the "recently used"-ness of the key.
-func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) {
+func (c *Cache) Peek(key interface{}) (interface{}, bool) {
 	c.lock.RLock()
-	value, ok = c.lru.Peek(key)
-	c.lock.RUnlock()
-	return value, ok
+	defer c.lock.RUnlock()
+	return c.lru.Peek(key)
 }
 
 // ContainsOrAdd checks if a key is in the cache  without updating the
 // recent-ness or deleting it for being stale,  and if not, adds the value.
 // Returns whether found and whether an eviction occurred.
-func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evicted bool) {
+func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evict bool) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
 	if c.lru.Contains(key) {
 		return true, false
+	} else {
+		evict := c.lru.Add(key, value)
+		return false, evict
 	}
-	evicted = c.lru.Add(key, value)
-	return false, evicted
 }
 
 // Remove removes the provided key from the cache.
@@ -102,15 +102,13 @@ func (c *Cache) RemoveOldest() {
 // Keys returns a slice of the keys in the cache, from oldest to newest.
 func (c *Cache) Keys() []interface{} {
 	c.lock.RLock()
-	keys := c.lru.Keys()
-	c.lock.RUnlock()
-	return keys
+	defer c.lock.RUnlock()
+	return c.lru.Keys()
 }
 
 // Len returns the number of items in the cache.
 func (c *Cache) Len() int {
 	c.lock.RLock()
-	length := c.lru.Len()
-	c.lock.RUnlock()
-	return length
+	defer c.lock.RUnlock()
+	return c.lru.Len()
 }