[#969] policer: Make error skip thread-safe

Introduces in afd2ba9a66.
Refs #914

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/services/policer/process.go

@@ -3,6 +3,7 @@ package policer
 import (
 	"context"
 	"errors"
+	"sync"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -35,9 +36,7 @@ func (p *Policer) shardPolicyWorker(ctx context.Context) {
 			p.log.Warn(logs.PolicerFailureAtObjectSelectForReplication, zap.Error(err))
 		}
 
-		// contains all errors logged in this iteration for each container
-		cnrErrSkip := make(map[cid.ID][]error)
-
+		skipMap := newSkipMap()
 		for i := range addrs {
 			select {
 			case <-ctx.Done():
@@ -59,12 +58,10 @@ func (p *Policer) shardPolicyWorker(ctx context.Context) {
 
 					if p.objsInWork.add(addr.Address) {
 						err := p.processObject(ctx, addr)
-						if err != nil && !skipLog(cnrErrSkip[addr.Address.Container()], err) {
+						if err != nil && !skipMap.addSeenError(addr.Address.Container(), err) {
 							p.log.Error(logs.PolicerUnableToProcessObj,
 								zap.Stringer("object", addr.Address),
 								zap.String("error", err.Error()))
-
-							cnrErrSkip[addr.Address.Container()] = append(cnrErrSkip[addr.Address.Container()], err)
 						}
 						p.cache.Add(addr.Address, time.Now())
 						p.objsInWork.remove(addr.Address)
@@ -79,11 +76,28 @@ func (p *Policer) shardPolicyWorker(ctx context.Context) {
 	}
 }
 
-func skipLog(errs []error, err error) bool {
-	for _, e := range errs {
+type errMap struct {
+	sync.Mutex
+	skipMap map[cid.ID][]error
+}
+
+func newSkipMap() *errMap {
+	return &errMap{
+		skipMap: make(map[cid.ID][]error),
+	}
+}
+
+// addSeenError marks err as seen error for the container.
+// Returns true is the error has already been added.
+func (m *errMap) addSeenError(cnr cid.ID, err error) bool {
+	m.Lock()
+	defer m.Unlock()
+
+	for _, e := range m.skipMap[cnr] {
 		if errors.Is(err, e) {
 			return true
 		}
 	}
+	m.skipMap[cnr] = append(m.skipMap[cnr], err)
 	return false
 }