[#223] placement: Fix local and single-success placement traversal

In previous implementation placement traverser processed incorrectly with
local placement build. Also entity incorrectly traversed the placement
vectors for fixed number read operations until success. The erroneous
behavior was due to the use of a vector number of successes instead of
a scalar number in these scenarios.

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

pkg/services/object_manager/placement/traverser.go

@@ -35,7 +35,9 @@ type Traverser struct {
 }
 
 type cfg struct {
-	rem int
+	trackCopies bool
+
+	flatSuccess *uint32
 
 	addr *object.Address
 
@@ -52,6 +54,7 @@ var errNilPolicy = errors.New("placement policy is nil")
 
 func defaultCfg() *cfg {
 	return &cfg{
+		trackCopies: true,
 		addr:        object.NewAddress(),
 	}
 }
@@ -77,17 +80,21 @@ func NewTraverser(opts ...Option) (*Traverser, error) {
 		return nil, errors.Wrap(err, "could not build placement")
 	}
 
+	var rem []int
+	if cfg.flatSuccess != nil {
+		ns = flatNodes(ns)
+		rem = []int{int(*cfg.flatSuccess)}
+	} else {
 		rs := cfg.policy.Replicas()
-	rem := make([]int, 0, len(rs))
+		rem = make([]int, 0, len(rs))
 
 		for i := range rs {
-		cnt := cfg.rem
-
-		if cnt == 0 {
-			cnt = int(rs[i].Count())
+			if cfg.trackCopies {
+				rem = append(rem, int(rs[i].Count()))
+			} else {
+				rem = append(rem, -1)
+			}
 		}
-
-		rem = append(rem, cnt)
 	}
 
 	return &Traverser{
@@ -97,6 +104,20 @@ func NewTraverser(opts ...Option) (*Traverser, error) {
 	}, nil
 }
 
+func flatNodes(ns []netmap.Nodes) []netmap.Nodes {
+	sz := 0
+	for i := range ns {
+		sz += len(ns[i])
+	}
+
+	flat := make(netmap.Nodes, 0, sz)
+	for i := range ns {
+		flat = append(flat, ns[i]...)
+	}
+
+	return []netmap.Nodes{flat}
+}
+
 // Next returns next unprocessed address of the object placement.
 //
 // Returns nil if no nodes left or traversal operation succeeded.
@@ -193,13 +214,13 @@ func ForObject(id *object.ID) Option {
 	}
 }
 
-// SuccessAfter is a success number setting option.
+// SuccessAfter is a flat success number setting option.
 //
 // Option has no effect if the number is not positive.
-func SuccessAfter(v int) Option {
+func SuccessAfter(v uint32) Option {
 	return func(c *cfg) {
 		if v > 0 {
-			c.rem = v
+			c.flatSuccess = &v
 		}
 	}
 }
@@ -207,6 +228,6 @@ func SuccessAfter(v int) Option {
 // WithoutSuccessTracking disables success tracking in traversal.
 func WithoutSuccessTracking() Option {
 	return func(c *cfg) {
-		c.rem = -1
+		c.trackCopies = false
 	}
 }

pkg/services/object_manager/placement/traverser_test.go

@@ -7,6 +7,7 @@ import (
 	"github.com/nspcc-dev/neofs-api-go/pkg/container"
 	"github.com/nspcc-dev/neofs-api-go/pkg/netmap"
 	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/network"
 	"github.com/stretchr/testify/require"
 )
 
@@ -114,34 +115,21 @@ func TestTraverserObjectScenarios(t *testing.T) {
 
 		tr, err := NewTraverser(
 			ForContainer(cnr),
-			UseBuilder(&testBuilder{vectors: nodesCopy}),
+			UseBuilder(&testBuilder{
+				vectors: nodesCopy,
+			}),
 			SuccessAfter(1),
 		)
 		require.NoError(t, err)
 
-		fn := func(curVector int) {
-			for i := 0; i < selectors[curVector]; i++ {
-				addrs := tr.Next()
-				require.Len(t, addrs, 1)
-
-				require.Equal(t, nodes[curVector][i].Address(), addrs[0].String())
+		for i := 0; i < len(nodes[0]); i++ {
+			require.NotNil(t, tr.Next())
 		}
 
-			require.Empty(t, tr.Next())
-			require.False(t, tr.Success())
+		n, err := network.AddressFromString(nodes[1][0].Address())
+		require.NoError(t, err)
 
-			tr.SubmitSuccess()
-		}
-
-		for i := range selectors {
-			fn(i)
-
-			if i < len(selectors)-1 {
-				require.False(t, tr.Success())
-			} else {
-				require.True(t, tr.Success())
-			}
-		}
+		require.Equal(t, []*network.Address{n}, tr.Next())
 	})
 
 	t.Run("put scenario", func(t *testing.T) {
@@ -186,4 +174,32 @@ func TestTraverserObjectScenarios(t *testing.T) {
 			}
 		}
 	})
+
+	t.Run("local operation scenario", func(t *testing.T) {
+		selectors := []int{2, 3}
+		replicas := []int{1, 2}
+
+		nodes, cnr := testPlacement(t, selectors, replicas)
+
+		tr, err := NewTraverser(
+			ForContainer(cnr),
+			UseBuilder(&testBuilder{
+				vectors: []netmap.Nodes{{nodes[1][1]}}, // single node (local)
+			}),
+			SuccessAfter(1),
+		)
+		require.NoError(t, err)
+
+		require.NotEmpty(t, tr.Next())
+		require.False(t, tr.Success())
+
+		// add 1 OK
+		tr.SubmitSuccess()
+
+		// nothing more to do
+		require.Empty(t, tr.Next())
+
+		// common success
+		require.True(t, tr.Success())
+	})
 }