Update dependencies / vendor (#1146)

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

@@ -37,7 +37,7 @@ func (c *Cache) Purge() {
 	c.lock.Unlock()
 }
 
-// Add adds a value to the cache.  Returns true if an eviction occurred.
+// Add adds a value to the cache. Returns true if an eviction occurred.
 func (c *Cache) Add(key, value interface{}) (evicted bool) {
 	c.lock.Lock()
 	evicted = c.lru.Add(key, value)
@@ -71,8 +71,8 @@ func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) {
 	return value, ok
 }
 
-// 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.
+// 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) {
 	c.lock.Lock()
@@ -85,6 +85,22 @@ func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evicted bool) {
 	return false, evicted
 }
 
+// PeekOrAdd 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) PeekOrAdd(key, value interface{}) (previous interface{}, ok, evicted bool) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	previous, ok = c.lru.Peek(key)
+	if ok {
+		return previous, true, false
+	}
+
+	evicted = c.lru.Add(key, value)
+	return nil, false, evicted
+}
+
 // Remove removes the provided key from the cache.
 func (c *Cache) Remove(key interface{}) (present bool) {
 	c.lock.Lock()