[#726] writecache: Fix small object flush for BBolt

Do not marshal object twice.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/writecache/writecachebbolt/cachebbolt.go

@@ -29,7 +29,7 @@ type cache struct {
 	compressFlags map[string]struct{}
 
 	// flushCh is a channel with objects to flush.
-	flushCh chan *objectSDK.Object
+	flushCh chan objectInfo
 	// closeCh is close channel, protected by modeMtx.
 	closeCh chan struct{}
 	// wg is a wait group for flush workers.
@@ -62,7 +62,7 @@ var (
 // New creates new writecache instance.
 func New(opts ...Option) writecache.Cache {
 	c := &cache{
-		flushCh: make(chan *objectSDK.Object),
+		flushCh: make(chan objectInfo),
 		mode:    mode.ReadWrite,
 
 		compressFlags: make(map[string]struct{}),

pkg/local_object_storage/writecache/writecachebbolt/flush.go

@@ -79,7 +79,6 @@ func (c *cache) runFlushLoop() {
 
 func (c *cache) flushSmallObjects() {
 	var lastKey []byte
-	var m []objectInfo
 	for {
 		select {
 		case <-c.closeCh:
@@ -87,7 +86,7 @@ func (c *cache) flushSmallObjects() {
 		default:
 		}
 
-		m = m[:0]
+		var m []objectInfo
 
 		c.modeMtx.RLock()
 		if c.readOnly() {
@@ -133,10 +132,11 @@ func (c *cache) flushSmallObjects() {
 			if err := obj.Unmarshal(m[i].data); err != nil {
 				continue
 			}
+			m[i].obj = obj
 
 			count++
 			select {
-			case c.flushCh <- obj:
+			case c.flushCh <- m[i]:
 			case <-c.closeCh:
 				c.modeMtx.RUnlock()
 				return
@@ -231,22 +231,22 @@ func (c *cache) flushFSTree(ctx context.Context, ignoreErrors bool) error {
 func (c *cache) workerFlushSmall() {
 	defer c.wg.Done()
 
-	var obj *objectSDK.Object
+	var objInfo objectInfo
 	for {
 		// Give priority to direct put.
 		select {
-		case obj = <-c.flushCh:
+		case objInfo = <-c.flushCh:
 		case <-c.closeCh:
 			return
 		}
 
-		err := c.flushObject(context.TODO(), obj, nil, writecache.StorageTypeDB)
+		err := c.flushObject(context.TODO(), objInfo.obj, objInfo.data, writecache.StorageTypeDB)
 		if err != nil {
 			// Error is handled in flushObject.
 			continue
 		}
 
-		c.deleteFromDB(objectCore.AddressOf(obj).EncodeToString())
+		c.deleteFromDB(objInfo.addr)
 	}
 }