[#1085] writecache: allow to ignore errors during iteration

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/local_object_storage/shard/evacuate.go

@@ -7,6 +7,7 @@ import (
 	"os"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 )
 
 var dumpMagic = []byte("NEOF")
@@ -72,7 +73,7 @@ func (s *Shard) Evacuate(prm *EvacuatePrm) (*EvacuateRes, error) {
 	var count int
 
 	if s.hasWriteCache() {
-		err := s.writeCache.Iterate(func(data []byte) error {
+		err := s.writeCache.Iterate(new(writecache.IterationPrm).WithHandler(func(data []byte) error {
 			var size [4]byte
 			binary.LittleEndian.PutUint32(size[:], uint32(len(data)))
 			if _, err := w.Write(size[:]); err != nil {
@@ -85,7 +86,7 @@ func (s *Shard) Evacuate(prm *EvacuatePrm) (*EvacuateRes, error) {
 
 			count++
 			return nil
-		})
+		}))
 		if err != nil {
 			return nil, err
 		}

pkg/local_object_storage/writecache/iterate.go

@@ -12,10 +12,28 @@ import (
 // ErrNoDefaultBucket is returned by IterateDB when default bucket for objects is missing.
 var ErrNoDefaultBucket = errors.New("no default bucket")
 
+// IterationPrm contains iteration parameters.
+type IterationPrm struct {
+	handler      func([]byte) error
+	ignoreErrors bool
+}
+
+// WithHandler sets a callback to be executed on every object.
+func (p *IterationPrm) WithHandler(f func([]byte) error) *IterationPrm {
+	p.handler = f
+	return p
+}
+
+// WithIgnoreErrors sets a flag indicating that errors should be ignored.
+func (p *IterationPrm) WithIgnoreErrors(ignore bool) *IterationPrm {
+	p.ignoreErrors = ignore
+	return p
+}
+
 // Iterate iterates over all objects present in write cache.
 // This is very difficult to do correctly unless write-cache is put in read-only mode.
 // Thus we silently fail if shard is not in read-only mode to avoid reporting misleading results.
-func (c *cache) Iterate(f func([]byte) error) error {
+func (c *cache) Iterate(prm *IterationPrm) error {
 	c.modeMtx.RLock()
 	defer c.modeMtx.RUnlock()
 	if c.mode != ModeReadOnly {
@@ -28,7 +46,7 @@ func (c *cache) Iterate(f func([]byte) error) error {
 			if _, ok := c.flushed.Peek(string(k)); ok {
 				return nil
 			}
-			return f(data)
+			return prm.handler(data)
 		})
 	})
 	if err != nil {
@@ -39,8 +57,8 @@ func (c *cache) Iterate(f func([]byte) error) error {
 		if _, ok := c.flushed.Peek(addr.String()); ok {
 			return nil
 		}
-		return f(data)
+		return prm.handler(data)
-	}))
+	}).WithIgnoreErrors(prm.ignoreErrors))
 }
 
 // IterateDB iterates over all objects stored in bbolt.DB instance and passes them to f until error return.

pkg/local_object_storage/writecache/writecache.go

@@ -20,7 +20,7 @@ type Cache interface {
 	Get(*objectSDK.Address) (*object.Object, error)
 	Head(*objectSDK.Address) (*object.Object, error)
 	Delete(*objectSDK.Address) error
-	Iterate(func(data []byte) error) error
+	Iterate(*IterationPrm) error
 	Put(*object.Object) error
 	SetMode(Mode)
 	DumpInfo() Info