[#53] object/range: Share object range traverser between services

Replace object range chain utilities to object/util package in order to
reuse it in other services.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/services/object/range/prm.go

@@ -10,8 +10,6 @@ type Prm struct {
 	addr *object.Address
 
 	rng *object.Range
-
-	traverser *rangeTraverser
 }
 
 func (p *Prm) OnlyLocal(v bool) *Prm {

pkg/services/object/range/service.go

@@ -11,6 +11,7 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/localstore"
 	"github.com/nspcc-dev/neofs-node/pkg/network"
 	headsvc "github.com/nspcc-dev/neofs-node/pkg/services/object/head"
+	objutil "github.com/nspcc-dev/neofs-node/pkg/services/object/util"
 	"github.com/nspcc-dev/neofs-node/pkg/util"
 	"github.com/pkg/errors"
 )
@@ -82,7 +83,7 @@ func (s *Service) GetRange(ctx context.Context, prm *Prm) (*Result, error) {
 		right = origin
 	}
 
-	rngTraverser := newRangeTraverser(originSize, right, prm.rng)
+	rngTraverser := objutil.NewRangeTraverser(originSize, right, prm.rng)
 	if err := s.fillTraverser(ctx, prm, rngTraverser); err != nil {
 		return nil, errors.Wrapf(err, "(%T) could not fill range traverser", s)
 	}
@@ -99,17 +100,17 @@ func (s *Service) GetRange(ctx context.Context, prm *Prm) (*Result, error) {
 	}, nil
 }
 
-func (s *Service) fillTraverser(ctx context.Context, prm *Prm, traverser *rangeTraverser) error {
+func (s *Service) fillTraverser(ctx context.Context, prm *Prm, traverser *objutil.RangeTraverser) error {
 	addr := object.NewAddress()
 	addr.SetContainerID(prm.addr.GetContainerID())
 
 	for {
-		next := traverser.next()
+		nextID, nextRng := traverser.Next()
-		if next.rng != nil {
+		if nextRng != nil {
 			return nil
 		}
 
-		addr.SetObjectID(next.id)
+		addr.SetObjectID(nextID)
 
 		head, err := s.headSvc.Head(ctx, new(headsvc.Prm).
 			WithAddress(addr).
@@ -119,7 +120,7 @@ func (s *Service) fillTraverser(ctx context.Context, prm *Prm, traverser *rangeT
 			return errors.Wrapf(err, "(%T) could not receive object header", s)
 		}
 
-		traverser.pushHeader(head.Header())
+		traverser.PushHeader(head.Header())
 	}
 }
 

pkg/services/object/range/streamer.go

@@ -28,7 +28,7 @@ type streamer struct {
 
 	traverser *placement.Traverser
 
-	rangeTraverser *rangeTraverser
+	rangeTraverser *util.RangeTraverser
 
 	ch chan []byte
 }
@@ -58,7 +58,7 @@ func (p *streamer) Recv() (*Response, error) {
 		return nil, errors.Wrapf(p.ctx.Err(), "(%T) stream is stopped by context", p)
 	case v, ok := <-p.ch:
 		if !ok {
-			if p.rangeTraverser.next().rng.GetLength() != 0 {
+			if _, rng := p.rangeTraverser.Next(); rng.GetLength() != 0 {
 				return nil, errors.Errorf("(%T) incomplete get payload range", p)
 			}
 
@@ -135,15 +135,15 @@ loop:
 		default:
 		}
 
-		nextRange := p.rangeTraverser.next()
+		nextID, nextRange := p.rangeTraverser.Next()
-		if nextRange.rng.GetLength() == 0 {
+		if nextRange.GetLength() == 0 {
 			break
-		} else if err := p.switchToObject(nextRange.id); err != nil {
+		} else if err := p.switchToObject(nextID); err != nil {
 			// TODO: log error
 			break
 		}
 
-		objAddr.SetObjectID(nextRange.id)
+		objAddr.SetObjectID(nextID)
 
 	subloop:
 		for {
@@ -173,7 +173,7 @@ loop:
 					if network.IsLocalAddress(p.localAddrSrc, addr) {
 						rngWriter = &localRangeWriter{
 							addr:    objAddr,
-							rng:     nextRange.rng,
+							rng:     nextRange,
 							storage: p.localStore,
 						}
 					} else {
@@ -182,7 +182,7 @@ loop:
 							key:  p.key,
 							node: addr,
 							addr: objAddr,
-							rng:  nextRange.rng,
+							rng:  nextRange,
 						}
 					}
 
@@ -194,12 +194,12 @@ loop:
 						// TODO: log error
 					}
 
-					ln := nextRange.rng.GetLength()
+					ln := nextRange.GetLength()
 					uw := uint64(written)
 
-					p.rangeTraverser.pushSuccessSize(uw)
+					p.rangeTraverser.PushSuccessSize(uw)
-					nextRange.rng.SetLength(ln - uw)
+					nextRange.SetLength(ln - uw)
-					nextRange.rng.SetOffset(nextRange.rng.GetOffset() + uw)
+					nextRange.SetOffset(nextRange.GetOffset() + uw)
 				}); err != nil {
 					wg.Done()
 					// TODO: log error
@@ -208,7 +208,7 @@ loop:
 
 				wg.Wait()
 
-				if nextRange.rng.GetLength() == 0 {
+				if nextRange.GetLength() == 0 {
 					p.traverser.SubmitSuccess()
 					break subloop
 				}

pkg/services/object/util/chain.go

@@ -0,0 +1,106 @@
+package util
+
+import (
+	"fmt"
+
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+
+	"github.com/nspcc-dev/neofs-node/pkg/core/object"
+)
+
+type RangeTraverser struct {
+	chain *rangeChain
+
+	seekBounds *rangeBounds
+}
+
+type rangeBounds struct {
+	left, right uint64
+}
+
+type rangeChain struct {
+	next, prev *rangeChain
+
+	bounds *rangeBounds
+
+	id *objectSDK.ID
+}
+
+func NewRangeTraverser(originSize uint64, rightElement *object.Object, rngSeek *objectSDK.Range) *RangeTraverser {
+	right := &rangeChain{
+		bounds: &rangeBounds{
+			left:  originSize - rightElement.GetPayloadSize(),
+			right: originSize,
+		},
+		id: rightElement.GetID(),
+	}
+
+	left := &rangeChain{
+		id: rightElement.GetPreviousID(),
+	}
+
+	left.next, right.prev = right, left
+
+	return &RangeTraverser{
+		chain: right,
+		seekBounds: &rangeBounds{
+			left:  rngSeek.GetOffset(),
+			right: rngSeek.GetOffset() + rngSeek.GetLength(),
+		},
+	}
+}
+
+func (c *RangeTraverser) Next() (id *objectSDK.ID, rng *objectSDK.Range) {
+	left := c.chain.bounds.left
+	seekLeft := c.seekBounds.left
+
+	if left > seekLeft {
+		id = c.chain.prev.id
+	} else {
+		id = c.chain.id
+		rng = objectSDK.NewRange()
+		rng.SetOffset(seekLeft - left)
+		rng.SetLength(min(c.chain.bounds.right, c.seekBounds.right) - seekLeft)
+	}
+
+	return
+}
+
+func min(a, b uint64) uint64 {
+	if a < b {
+		return a
+	}
+
+	return b
+}
+
+func (c *RangeTraverser) PushHeader(obj *object.Object) {
+	id := obj.GetID()
+	if !id.Equal(c.chain.prev.id) {
+		panic(fmt.Sprintf("(%T) unexpected identifier in header", c))
+	}
+
+	sz := obj.GetPayloadSize()
+
+	c.chain.prev.bounds = &rangeBounds{
+		left:  c.chain.bounds.left - sz,
+		right: c.chain.bounds.left,
+	}
+
+	c.chain = c.chain.prev
+
+	if prev := obj.GetPreviousID(); prev != nil {
+		c.chain.prev = &rangeChain{
+			next: c.chain,
+			id:   prev,
+		}
+	}
+}
+
+func (c *RangeTraverser) PushSuccessSize(sz uint64) {
+	c.seekBounds.left += sz
+
+	if c.seekBounds.left >= c.chain.bounds.right && c.chain.next != nil {
+		c.chain = c.chain.next
+	}
+}