Fix/memory leak in freelist

fastcache.go

@@ -211,6 +211,18 @@ func (c *Cache) UpdateStats(s *Stats) {
 	s.InvalidValueHashErrors += atomic.LoadUint64(&c.bigStats.InvalidValueHashErrors)
 }
 
+func (c *Cache) ReloadFromFile(path string) error {
+	c.Reset()
+	var err error
+	c, err = load(c, path, 0)
+	return err
+}
+
+func (c *Cache) Close() error {
+	c.Reset()
+	return clearChunks()
+}
+
 type bucket struct {
 	mu sync.RWMutex
 

file.go

@@ -80,15 +80,15 @@ func (c *Cache) SaveToFileConcurrent(filePath string, concurrency int) error {
 //
 // See SaveToFile* for saving cache data to file.
 func LoadFromFile(filePath string) (*Cache, error) {
-	return load(filePath, 0)
+	return load(nil, filePath, 0)
 }
 
 // LoadFromFileOrNew tries loading cache data from the given filePath.
 //
 // The function falls back to creating new cache with the given maxBytes
 // capacity if error occurs during loading the cache from file.
 func LoadFromFileOrNew(filePath string, maxBytes int) *Cache {
-	c, err := load(filePath, maxBytes)
+	c, err := load(nil, filePath, maxBytes)
 	if err == nil {
 		return c
 	}
@@ -125,7 +125,7 @@ func (c *Cache) save(dir string, workersCount int) error {
 	return err
 }
 
-func load(filePath string, maxBytes int) (*Cache, error) {
+func load(oldCache *Cache, filePath string, maxBytes int) (*Cache, error) {
 	maxBucketChunks, err := loadMetadata(filePath)
 	if err != nil {
 		return nil, err
@@ -152,7 +152,12 @@ func load(filePath string, maxBytes int) (*Cache, error) {
 	}
 	results := make(chan error)
 	workersCount := 0
-	var c Cache
+	var c *Cache
+	if oldCache != nil {
+		c = oldCache
+	} else {
+		c = &Cache{}
+	}
 	for _, fi := range fis {
 		fn := fi.Name()
 		if fi.IsDir() || !dataFileRegexp.MatchString(fn) {
@@ -183,7 +188,7 @@ func load(filePath string, maxBytes int) (*Cache, error) {
 			b.m = make(map[uint64]uint64)
 		}
 	}
-	return &c, nil
+	return c, nil
 }
 
 func saveMetadata(c *Cache, dir string) error {

malloc_heap.go

@@ -9,3 +9,8 @@ func getChunk() []byte {
 func putChunk(chunk []byte) {
 	// No-op.
 }
+
+func clearChunks() error {
+	// No-op.
+	return nil
+}

malloc_mmap.go

@@ -13,7 +13,10 @@ import (
 const chunksPerAlloc = 1024
 
 var (
-	freeChunks     []*[chunkSize]byte
+	// chunks to hand out to the library
+	freeChunks []*[chunkSize]byte
+	// orignal slice from Mmap for book-keeping
+	baseChunks     [][]byte
 	freeChunksLock sync.Mutex
 )
 
@@ -26,6 +29,7 @@ func getChunk() []byte {
 		if err != nil {
 			panic(fmt.Errorf("cannot allocate %d bytes via mmap: %s", chunkSize*chunksPerAlloc, err))
 		}
+		baseChunks = append(baseChunks, data)
 		for len(data) > 0 {
 			p := (*[chunkSize]byte)(unsafe.Pointer(&data[0]))
 			freeChunks = append(freeChunks, p)
@@ -51,3 +55,16 @@ func putChunk(chunk []byte) {
 	freeChunks = append(freeChunks, p)
 	freeChunksLock.Unlock()
 }
+
+func clearChunks() error {
+	freeChunksLock.Lock()
+	defer freeChunksLock.Unlock()
+	freeChunks = nil
+	for _, baseChunk := range baseChunks {
+		if err := unix.Munmap(baseChunk); err != nil {
+			return err
+		}
+	}
+	baseChunks = nil
+	return nil
+}