[disk] avoid looking for items in the LRU index twice

Author: mostynb

cache/disk/disk.go

@@ -510,7 +510,7 @@ func (c *diskCache) availableOrTryProxy(kind cache.EntryKind, hash string, size
 					_ = f.Close()
 
 					c.mu.Lock()
-					c.lru.Remove(key)
+					c.lru.RemoveElement(listElem)
 					c.mu.Unlock()
 				} else {
 					return rc, item.size, false, nil

cache/disk/lru.go

@@ -241,14 +241,20 @@ func (c *SizedLRU) Get(key string) (lruItem, *list.Element) {
 	return lruItem{}, nil
 }
 
-// Remove removes a (key, value) from the cache
-func (c *SizedLRU) Remove(key string) {
-	if ele, hit := c.cache[key]; hit {
-		c.removeElement(ele)
+// Remove removes a (key, value) from the cache.
+func (c *SizedLRU) RemoveKey(key string) {
+	if elem, hit := c.cache[key]; hit {
+		c.removeElement(elem)
 		c.gaugeCacheLogicalBytes.Set(float64(c.uncompressedSize))
 	}
 }
 
+// Remove a *list.Element from the cache.
+func (c *SizedLRU) RemoveElement(elem *list.Element) {
+	c.removeElement(elem)
+	c.gaugeCacheLogicalBytes.Set(float64(c.uncompressedSize))
+}
+
 // Len returns the number of items in the cache
 func (c *SizedLRU) Len() int {
 	return len(c.cache)

cache/disk/lru_test.go

@@ -58,7 +58,7 @@ func TestBasics(t *testing.T) {
 	checkSizeAndNumItems(t, &lru, BlockSize, 1)
 
 	// Remove the item
-	lru.Remove(aKey)
+	lru.RemoveKey(aKey)
 	checkSizeAndNumItems(t, &lru, 0, 0)
 }
 
@@ -178,7 +178,7 @@ func TestReserveAtEvictionQueueLimit(t *testing.T) {
 	testutils.AssertEquals(t, BlockSize*2, lru.totalDiskSizePeak)
 
 	// Move large item into eviction queue.
-	lru.Remove(blockSize2Key)
+	lru.RemoveKey(blockSize2Key)
 	testutils.AssertEquals(t, BlockSize*2, lru.queuedEvictionsSize.Load())
 
 	// Accept reservation since not exceeding maxSizeHardLimit.