feat: Add function to check if cache contains a key

bigcache.go

@@ -229,6 +229,13 @@ func (c *BigCache) Iterator() *EntryInfoIterator {
  return newIterator(c)
 }
 
+// Contains returns whether the given key exists in cache
+func (c *BigCache) Contains(key string) bool {
+ hashedKey := c.hash.Sum64(key)
+ shard := c.getShard(hashedKey)
+ return shard.contains(key, hashedKey)
+}
+
 func (c *BigCache) onEvict(oldestEntry []byte, currentTimestamp uint64, evict func(reason RemoveReason) error) bool {
  oldestTimestamp := readTimestampFromEntry(oldestEntry)
  if currentTimestamp < oldestTimestamp {

bigcache_test.go

@@ -1388,3 +1388,31 @@ func TestRemoveNonExpiredData(t *testing.T) {
  noError(t, err)
  }
 }
+
+func TestContainsExists(t *testing.T) {
+ t.Parallel()
+
+ // given
+ cache, _ := New(context.Background(), DefaultConfig(5*time.Second))
+ value := []byte("value")
+
+ // when
+ cache.Set("key", value)
+ exists := cache.Contains("key")
+
+ // then
+ assertEqual(t, true, exists)
+}
+
+func TestContainsNotExists(t *testing.T) {
+ t.Parallel()
+
+ // given
+ cache, _ := New(context.Background(), DefaultConfig(5*time.Second))
+
+ // when
+ exists := cache.Contains("key")
+
+ // then
+ assertEqual(t, false, exists)
+}

shard.go

@@ -117,6 +117,16 @@ func (s *cacheShard) getValidWrapEntry(key string, hashedKey uint64) ([]byte, er
  return wrappedEntry, nil
 }
 
+func (s *cacheShard) contains(key string, hashedKey uint64) bool {
+ s.lock.RLock()
+ defer s.lock.RUnlock()
+ wrappedEntry, err := s.getWrappedEntry(hashedKey)
+ if err != nil {
+ return false
+ }
+ return key == readKeyFromEntry(wrappedEntry)
+}
+
 func (s *cacheShard) set(key string, hashedKey uint64, entry []byte) error {
  currentTimestamp := uint64(s.clock.Epoch())