Merge pull request #3774 from greatroar/archiver-pool

archiver: Remove cleanup goroutine from BufferPool

internal/archiver/buffer.go

@@ -1,52 +1,44 @@
 package archiver
 
-import (
-	"context"
-	"sync"
-)
-
 // Buffer is a reusable buffer. After the buffer has been used, Release should
 // be called so the underlying slice is put back into the pool.
 type Buffer struct {
 	Data []byte
-	Put  func(*Buffer)
+	pool *BufferPool
 }
 
 // Release puts the buffer back into the pool it came from.
 func (b *Buffer) Release() {
-	if b.Put != nil {
-		b.Put(b)
+	pool := b.pool
+	if pool == nil || cap(b.Data) > pool.defaultSize {
+		return
+	}
+
+	select {
+	case pool.ch <- b:
+	default:
 	}
 }
 
 // BufferPool implements a limited set of reusable buffers.
 type BufferPool struct {
 	ch          chan *Buffer
-	chM         sync.Mutex
 	defaultSize int
-	clearOnce   sync.Once
 }
 
-// NewBufferPool initializes a new buffer pool. When the context is cancelled,
-// all buffers are released. The pool stores at most max items. New buffers are
-// created with defaultSize, buffers that are larger are released and not put
-// back.
-func NewBufferPool(ctx context.Context, max int, defaultSize int) *BufferPool {
+// NewBufferPool initializes a new buffer pool. The pool stores at most max
+// items. New buffers are created with defaultSize. Buffers that have grown
+// larger are not put back.
+func NewBufferPool(max int, defaultSize int) *BufferPool {
 	b := &BufferPool{
 		ch:          make(chan *Buffer, max),
 		defaultSize: defaultSize,
 	}
-	go func() {
-		<-ctx.Done()
-		b.clear()
-	}()
 	return b
 }
 
 // Get returns a new buffer, either from the pool or newly allocated.
 func (pool *BufferPool) Get() *Buffer {
-	pool.chM.Lock()
-	defer pool.chM.Unlock()
 	select {
 	case buf := <-pool.ch:
 		return buf
@@ -54,36 +46,9 @@ func (pool *BufferPool) Get() *Buffer {
 	}
 
 	b := &Buffer{
-		Put:  pool.Put,
 		Data: make([]byte, pool.defaultSize),
+		pool: pool,
 	}
 
 	return b
 }
-
-// Put returns a buffer to the pool for reuse.
-func (pool *BufferPool) Put(b *Buffer) {
-	if cap(b.Data) > pool.defaultSize {
-		return
-	}
-
-	pool.chM.Lock()
-	defer pool.chM.Unlock()
-	select {
-	case pool.ch <- b:
-	default:
-	}
-}
-
-// clear empties the buffer so that all items can be garbage collected.
-func (pool *BufferPool) clear() {
-	pool.clearOnce.Do(func() {
-		ch := pool.ch
-		pool.chM.Lock()
-		pool.ch = nil
-		pool.chM.Unlock()
-		close(ch)
-		for range ch {
-		}
-	})
-}

internal/archiver/file_saver.go

@@ -76,7 +76,7 @@ func NewFileSaver(ctx context.Context, t *tomb.Tomb, save SaveBlobFn, pol chunke
 
 	s := &FileSaver{
 		saveBlob:     save,
-		saveFilePool: NewBufferPool(ctx, int(poolSize), chunker.MaxSize),
+		saveFilePool: NewBufferPool(int(poolSize), chunker.MaxSize),
 		pol:          pol,
 		ch:           ch,