From 93bd6be74330d5a7bd882b6e570bdc099de731aa Mon Sep 17 00:00:00 2001
From: Pavel Karpy <carpawell@nspcc.ru>
Date: Mon, 27 Dec 2021 14:04:07 +0300
Subject: [PATCH] [#1057] shard: Do not allow memory change operations in
 "read-only"

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
---
 pkg/local_object_storage/shard/delete.go |  4 ++++
 pkg/local_object_storage/shard/gc.go     |  5 +++++
 pkg/local_object_storage/shard/inhume.go |  6 ++++++
 pkg/local_object_storage/shard/move.go   |  4 ++++
 pkg/local_object_storage/shard/put.go    |  6 ++++++
 pkg/local_object_storage/shard/shard.go  | 15 ++++++++++++---
 6 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/pkg/local_object_storage/shard/delete.go b/pkg/local_object_storage/shard/delete.go
index 025b9038..6ea7897b 100644
--- a/pkg/local_object_storage/shard/delete.go
+++ b/pkg/local_object_storage/shard/delete.go
@@ -33,6 +33,10 @@ func (p *DeletePrm) WithAddresses(addr ...*objectSDK.Address) *DeletePrm {
 // Delete removes data from the shard's writeCache, metaBase and
 // blobStor.
 func (s *Shard) Delete(prm *DeletePrm) (*DeleteRes, error) {
+	if s.getMode() == ModeReadOnly {
+		return nil, ErrReadOnlyMode
+	}
+
 	ln := len(prm.addr)
 	delSmallPrm := new(blobstor.DeleteSmallPrm)
 	delBigPrm := new(blobstor.DeleteBigPrm)
diff --git a/pkg/local_object_storage/shard/gc.go b/pkg/local_object_storage/shard/gc.go
index 336198ac..b29029fb 100644
--- a/pkg/local_object_storage/shard/gc.go
+++ b/pkg/local_object_storage/shard/gc.go
@@ -171,7 +171,12 @@ func (gc *gc) stop() {
 
 // iterates over metabase graveyard and deletes objects
 // with GC-marked graves.
+// Does nothing if shard is in "read-only" mode.
 func (s *Shard) removeGarbage() {
+	if s.getMode() == ModeReadOnly {
+		return
+	}
+
 	buf := make([]*object.Address, 0, s.rmBatchSize)
 
 	// iterate over metabase graveyard and accumulate
diff --git a/pkg/local_object_storage/shard/inhume.go b/pkg/local_object_storage/shard/inhume.go
index 099de855..4a17831d 100644
--- a/pkg/local_object_storage/shard/inhume.go
+++ b/pkg/local_object_storage/shard/inhume.go
@@ -43,7 +43,13 @@ func (p *InhumePrm) MarkAsGarbage(addr ...*objectSDK.Address) *InhumePrm {
 
 // Inhume calls metabase. Inhume method to mark object as removed. It won't be
 // removed physically from blobStor and metabase until `Delete` operation.
+//
+// Returns ErrReadOnlyMode error if shard is in "read-only" mode.
 func (s *Shard) Inhume(prm *InhumePrm) (*InhumeRes, error) {
+	if s.getMode() == ModeReadOnly {
+		return nil, ErrReadOnlyMode
+	}
+
 	if s.hasWriteCache() {
 		for i := range prm.target {
 			_ = s.writeCache.Delete(prm.target[i])
diff --git a/pkg/local_object_storage/shard/move.go b/pkg/local_object_storage/shard/move.go
index d454a31d..f9b963c5 100644
--- a/pkg/local_object_storage/shard/move.go
+++ b/pkg/local_object_storage/shard/move.go
@@ -27,6 +27,10 @@ func (p *ToMoveItPrm) WithAddress(addr *objectSDK.Address) *ToMoveItPrm {
 // ToMoveIt calls metabase.ToMoveIt method to mark object as relocatable to
 // another shard.
 func (s *Shard) ToMoveIt(prm *ToMoveItPrm) (*ToMoveItRes, error) {
+	if s.getMode() == ModeReadOnly {
+		return nil, ErrReadOnlyMode
+	}
+
 	err := meta.ToMoveIt(s.metaBase, prm.addr)
 	if err != nil {
 		s.log.Debug("could not mark object for shard relocation in metabase",
diff --git a/pkg/local_object_storage/shard/put.go b/pkg/local_object_storage/shard/put.go
index 2ee802f1..2a17eae0 100644
--- a/pkg/local_object_storage/shard/put.go
+++ b/pkg/local_object_storage/shard/put.go
@@ -30,7 +30,13 @@ func (p *PutPrm) WithObject(obj *object.Object) *PutPrm {
 //
 // Returns any error encountered that
 // did not allow to completely save the object.
+//
+// Returns ErrReadOnlyMode error if shard is in "read-only" mode.
 func (s *Shard) Put(prm *PutPrm) (*PutRes, error) {
+	if s.getMode() == ModeReadOnly {
+		return nil, ErrReadOnlyMode
+	}
+
 	putPrm := new(blobstor.PutPrm) // form Put parameters
 	putPrm.SetObject(prm.obj)
 
diff --git a/pkg/local_object_storage/shard/shard.go b/pkg/local_object_storage/shard/shard.go
index b585bc40..32f4affc 100644
--- a/pkg/local_object_storage/shard/shard.go
+++ b/pkg/local_object_storage/shard/shard.go
@@ -20,8 +20,6 @@ type Shard struct {
 
 	gc *gc
 
-	mode *atomic.Uint32
-
 	writeCache writecache.Cache
 
 	blobStor *blobstor.BlobStor
@@ -36,6 +34,8 @@ type Option func(*cfg)
 type ExpiredObjectsCallback func(context.Context, []*object.Address)
 
 type cfg struct {
+	mode *atomic.Uint32
+
 	refillMetabase bool
 
 	rmBatchSize int
@@ -59,6 +59,7 @@ type cfg struct {
 
 func defaultCfg() *cfg {
 	return &cfg{
+		mode:        atomic.NewUint32(uint32(ModeReadWrite)),
 		rmBatchSize: 100,
 		log:         zap.L(),
 		gcCfg:       defaultGCCfg(),
@@ -86,7 +87,6 @@ func New(opts ...Option) *Shard {
 
 	s := &Shard{
 		cfg:        c,
-		mode:       atomic.NewUint32(0), // TODO: init with particular mode
 		blobStor:   bs,
 		metaBase:   mb,
 		writeCache: writeCache,
@@ -197,6 +197,15 @@ func WithRefillMetabase(v bool) Option {
 	}
 }
 
+// WithMode returns option to set shard's mode. Mode must be one of the predefined:
+//	- ModeReadWrite;
+//	- ModeReadOnly.
+func WithMode(v Mode) Option {
+	return func(c *cfg) {
+		c.mode.Store(uint32(v))
+	}
+}
+
 func (s *Shard) fillInfo() {
 	s.cfg.info.MetaBaseInfo = s.metaBase.DumpInfo()
 	s.cfg.info.BlobStorInfo = s.blobStor.DumpInfo()