[#249] pkg/netmap: Add CBF field in placement context

If CBF value is not set, then netmap package uses default CBF
value. However it modifies placement policy structure in
`GetContainerNodes()` because policy passed as a pointer.

Instead package can store CBF value in internal context and use
it without policy modification.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/netmap/context.go

@@ -29,6 +29,9 @@ type Context struct {
 	// weightFunc is a weighting function for determining node priority.
 	// By default in combines favours low price and high capacity.
 	weightFunc weightFunc
+	// container backup factor is a factor for selector counters that expand
+	// amount of chosen nodes.
+	cbf uint32
 }
 
 // Various validation errors.
@@ -56,6 +59,7 @@ func NewContext(nm *Netmap) *Context {
 		numCache:   make(map[*Filter]uint64),
 		aggregator: newMeanIQRAgg,
 		weightFunc: GetDefaultWeightFunc(nm.Nodes),
+		cbf:        defaultCBF,
 	}
 }
 
@@ -66,6 +70,14 @@ func (c *Context) setPivot(pivot []byte) {
 	}
 }
 
+func (c *Context) setCBF(cbf uint32) {
+	if cbf == 0 {
+		c.cbf = defaultCBF
+	} else {
+		c.cbf = cbf
+	}
+}
+
 // GetDefaultWeightFunc returns default weighting function.
 func GetDefaultWeightFunc(ns Nodes) weightFunc {
 	mean := newMeanAgg()

pkg/netmap/netmap.go

@@ -50,10 +50,7 @@ func (m *Netmap) GetPlacementVectors(cnt ContainerNodes, pivot []byte) ([]Nodes,
 func (m *Netmap) GetContainerNodes(p *PlacementPolicy, pivot []byte) (ContainerNodes, error) {
 	c := NewContext(m)
 	c.setPivot(pivot)
-
-	if p.ContainerBackupFactor() == 0 {
-		p.SetContainerBackupFactor(defaultCBF)
-	}
+	c.setCBF(p.ContainerBackupFactor())
 
 	if err := c.processFilters(p); err != nil {
 		return nil, err

pkg/netmap/selector.go

@@ -69,7 +69,7 @@ func (c *Context) getSelection(p *PlacementPolicy, s *Selector) ([]Nodes, error)
 		}
 	}
 
-	maxNodesInBucket := nodesInBucket * int(p.ContainerBackupFactor())
+	maxNodesInBucket := nodesInBucket * int(c.cbf)
 	nodes := make([]Nodes, 0, len(buckets))
 	fallback := make([]Nodes, 0, len(buckets))
 

pkg/netmap/selector_test.go

@@ -270,6 +270,7 @@ func TestPlacementPolicy_ProcessSelectors(t *testing.T) {
 	nm, err := NewNetmap(NodesFromInfo(nodes))
 	require.NoError(t, err)
 	c := NewContext(nm)
+	c.setCBF(p.ContainerBackupFactor())
 	require.NoError(t, c.processFilters(p))
 	require.NoError(t, c.processSelectors(p))
 
@@ -277,7 +278,7 @@ func TestPlacementPolicy_ProcessSelectors(t *testing.T) {
 		sel := c.Selections[s.Name()]
 		s := c.Selectors[s.Name()]
 		bucketCount, nodesInBucket := GetNodesCount(p, s)
-		nodesInBucket *= int(p.ContainerBackupFactor())
+		nodesInBucket *= int(c.cbf)
 		targ := fmt.Sprintf("selector '%s'", s.Name())
 		require.Equal(t, bucketCount, len(sel), targ)
 		for _, res := range sel {
@@ -312,6 +313,7 @@ func TestPlacementPolicy_ProcessSelectorsHRW(t *testing.T) {
 	require.NoError(t, err)
 	c := NewContext(nm)
 	c.setPivot([]byte("containerID"))
+	c.setCBF(p.ContainerBackupFactor())
 	c.weightFunc = newWeightFunc(newMaxNorm(10000), newReverseMinNorm(1))
 	c.aggregator = func() aggregator {
 		return new(maxAgg)
@@ -388,6 +390,7 @@ func TestPlacementPolicy_ProcessSelectorsInvalid(t *testing.T) {
 			nm, err := NewNetmap(NodesFromInfo(nodes))
 			require.NoError(t, err)
 			c := NewContext(nm)
+			c.setCBF(tc.p.ContainerBackupFactor())
 			require.NoError(t, c.processFilters(tc.p))
 
 			err = c.processSelectors(tc.p)