From e6f89040400e713702c0a8e44b2a579fa6d30291 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <ctulhurider@gmail.com>
Date: Fri, 7 Oct 2022 13:19:31 +0400
Subject: [PATCH] [#1680] policer: Refactor tracking the processed nodes

Add clear methods with docs. Use the methods instead of direct map
and bool instructions.

Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>
---
 pkg/services/policer/check.go      | 52 ++++++++++++++++++++++++------
 pkg/services/policer/check_test.go | 24 ++++++++++++++
 2 files changed, 67 insertions(+), 9 deletions(-)
 create mode 100644 pkg/services/policer/check_test.go

diff --git a/pkg/services/policer/check.go b/pkg/services/policer/check.go
index b6f48faa4..569d49c56 100644
--- a/pkg/services/policer/check.go
+++ b/pkg/services/policer/check.go
@@ -13,10 +13,45 @@ import (
 	"go.uber.org/zap"
 )
 
+// tracks Policer's check progress
 type nodeCache map[uint64]bool
 
-func (n nodeCache) SubmitSuccessfulReplication(id uint64) {
-	n[id] = true
+func newNodeCache() *nodeCache {
+	m := make(map[uint64]bool)
+	return (*nodeCache)(&m)
+}
+
+// submits storage node as a candidate to store the object replica in case of
+// shortage.
+func (n *nodeCache) submitReplicaCandidate(node netmap.NodeInfo) {
+	(*n)[node.Hash()] = false
+}
+
+// submits storage node as a current object replica holder.
+func (n *nodeCache) submitReplicaHolder(node netmap.NodeInfo) {
+	(*n)[node.Hash()] = true
+}
+
+// processStatus returns current processing status of the storage node
+//
+//	>0 if node does not currently hold the object
+//	 0 if node already holds the object
+//	<0 if node has not been processed yet
+func (n *nodeCache) processStatus(node netmap.NodeInfo) int8 {
+	val, ok := (*n)[node.Hash()]
+	if !ok {
+		return -1
+	}
+
+	if val {
+		return 0
+	}
+
+	return 1
+}
+
+func (n *nodeCache) SubmitSuccessfulReplication(id uint64) {
+	(*n)[id] = true
 }
 
 func (p *Policer) processObject(ctx context.Context, addr oid.Address) {
@@ -68,7 +103,7 @@ func (p *Policer) processObject(ctx context.Context, addr oid.Address) {
 	}
 
 	// cached info about already checked nodes
-	var checkedNodes nodeCache = make(map[uint64]bool, numOfContainerNodes)
+	checkedNodes := newNodeCache()
 
 	for i := range nn {
 		select {
@@ -96,7 +131,7 @@ type processPlacementContext struct {
 }
 
 func (p *Policer) processNodes(ctx *processPlacementContext, addr oid.Address,
-	nodes []netmap.NodeInfo, shortage uint32, checkedNodes nodeCache) {
+	nodes []netmap.NodeInfo, shortage uint32, checkedNodes *nodeCache) {
 	prm := new(headsvc.RemoteHeadPrm).WithObjectAddress(addr)
 
 	for i := 0; shortage > 0 && i < len(nodes); i++ {
@@ -111,9 +146,8 @@ func (p *Policer) processNodes(ctx *processPlacementContext, addr oid.Address,
 
 			shortage--
 		} else {
-			nodeID := nodes[i].Hash()
-			if hasReplica, checked := checkedNodes[nodeID]; checked {
-				if hasReplica {
+			if status := checkedNodes.processStatus(nodes[i]); status >= 0 {
+				if status == 0 {
 					// node already contains replica, no need to replicate
 					nodes = append(nodes[:i], nodes[i+1:]...)
 					i--
@@ -130,7 +164,7 @@ func (p *Policer) processNodes(ctx *processPlacementContext, addr oid.Address,
 			cancel()
 
 			if client.IsErrObjectNotFound(err) {
-				checkedNodes[nodeID] = false
+				checkedNodes.submitReplicaCandidate(nodes[i])
 				continue
 			}
 
@@ -141,7 +175,7 @@ func (p *Policer) processNodes(ctx *processPlacementContext, addr oid.Address,
 				)
 			} else {
 				shortage--
-				checkedNodes[nodeID] = true
+				checkedNodes.submitReplicaHolder(nodes[i])
 			}
 		}
 
diff --git a/pkg/services/policer/check_test.go b/pkg/services/policer/check_test.go
new file mode 100644
index 000000000..d04c62502
--- /dev/null
+++ b/pkg/services/policer/check_test.go
@@ -0,0 +1,24 @@
+package policer
+
+import (
+	"testing"
+
+	netmaptest "github.com/nspcc-dev/neofs-sdk-go/netmap/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNodeCache(t *testing.T) {
+	cache := newNodeCache()
+	node := netmaptest.NodeInfo()
+
+	require.Negative(t, cache.processStatus(node))
+
+	cache.SubmitSuccessfulReplication(node.Hash())
+	require.Zero(t, cache.processStatus(node))
+
+	cache.submitReplicaCandidate(node)
+	require.Positive(t, cache.processStatus(node))
+
+	cache.submitReplicaHolder(node)
+	require.Zero(t, cache.processStatus(node))
+}