[#1992] writecache: Allow to open in NOSYNC mode

Applicable only to FSTree as we cannot handle corrupted databases
properly yet.

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

cmd/neofs-node/config.go

@@ -129,6 +129,7 @@ type shardCfg struct {
 		maxObjSize       uint64
 		flushWorkerCount int
 		sizeLimit        uint64
+		noSync           bool
 	}
 
 	piloramaCfg struct {
@@ -219,6 +220,7 @@ func (a *applicationConfiguration) readConfig(c *config.Config) error {
 			wc.smallObjectSize = writeCacheCfg.SmallObjectSize()
 			wc.flushWorkerCount = writeCacheCfg.WorkersNumber()
 			wc.sizeLimit = writeCacheCfg.SizeLimit()
+			wc.noSync = writeCacheCfg.NoSync()
 		}
 
 		// blobstor with substorages
@@ -644,7 +646,7 @@ func (c *cfg) shardOpts() []shardOptsWithID {
 				writecache.WithSmallObjectSize(wcRead.smallObjectSize),
 				writecache.WithFlushWorkersCount(wcRead.flushWorkerCount),
 				writecache.WithMaxCacheSize(wcRead.sizeLimit),
-
+				writecache.WithNoSync(wcRead.noSync),
 				writecache.WithLogger(c.log),
 			)
 		}

cmd/neofs-node/config/engine/config_test.go

@@ -68,6 +68,7 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, pl.MaxBatchSize(), 200)
 
 				require.Equal(t, false, wc.Enabled())
+				require.Equal(t, true, wc.NoSync())
 
 				require.Equal(t, "tmp/0/cache", wc.Path())
 				require.EqualValues(t, 16384, wc.SmallObjectSize())
@@ -113,6 +114,7 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, 100, pl.MaxBatchSize())
 
 				require.Equal(t, true, wc.Enabled())
+				require.Equal(t, false, wc.NoSync())
 
 				require.Equal(t, "tmp/1/cache", wc.Path())
 				require.EqualValues(t, 16384, wc.SmallObjectSize())

cmd/neofs-node/config/engine/shard/writecache/config.go

@@ -115,6 +115,13 @@ func (x *Config) SizeLimit() uint64 {
 	return SizeLimitDefault
 }
 
+// NoSync returns the value of "no_sync" config parameter.
+//
+// Returns false if the value is not a boolean.
+func (x *Config) NoSync() bool {
+	return config.BoolSafe((*config.Config)(x), "no_sync")
+}
+
 // BoltDB returns config instance for querying bolt db specific parameters.
 func (x *Config) BoltDB() *boltdbconfig.Config {
 	return (*boltdbconfig.Config)(x)

config/example/node.env

@@ -92,6 +92,7 @@ NEOFS_STORAGE_SHARD_0_RESYNC_METABASE=false
 NEOFS_STORAGE_SHARD_0_MODE=read-only
 ### Write cache config
 NEOFS_STORAGE_SHARD_0_WRITECACHE_ENABLED=false
+NEOFS_STORAGE_SHARD_0_WRITECACHE_NO_SYNC=true
 NEOFS_STORAGE_SHARD_0_WRITECACHE_PATH=tmp/0/cache
 NEOFS_STORAGE_SHARD_0_WRITECACHE_SMALL_OBJECT_SIZE=16384
 NEOFS_STORAGE_SHARD_0_WRITECACHE_MAX_OBJECT_SIZE=134217728

config/example/node.json

@@ -137,6 +137,7 @@
         "resync_metabase": false,
         "writecache": {
           "enabled": false,
+          "no_sync": true,
           "path": "tmp/0/cache",
           "small_object_size": 16384,
           "max_object_size": 134217728,

config/example/node.yaml

@@ -157,6 +157,7 @@ storage:
 
       writecache:
         enabled: false
+        no_sync: true
         path: tmp/0/cache  # write-cache root directory
         capacity: 3221225472  # approximate write-cache total size, bytes
 

pkg/local_object_storage/writecache/options.go

@@ -50,6 +50,8 @@ type options struct {
 	maxBatchSize int
 	// maxBatchDelay is the maximum batch wait time for the small object database.
 	maxBatchDelay time.Duration
+	// noSync is true iff FSTree allows unsynchronized writes.
+	noSync bool
 }
 
 // WithLogger sets logger.
@@ -130,3 +132,13 @@ func WithMaxBatchDelay(d time.Duration) Option {
 		}
 	}
 }
+
+// WithNoSync sets an option to allow returning to caller on PUT before write is persisted.
+// Note, that we use this flag for FSTree only and DO NOT use it for a bolt DB because
+// we cannot yet properly handle the corrupted database during the startup. This SHOULD NOT
+// be relied upon and may be changed in future.
+func WithNoSync(noSync bool) Option {
+	return func(o *options) {
+		o.noSync = noSync
+	}
+}

pkg/local_object_storage/writecache/storage.go

@@ -56,14 +56,12 @@ func (c *cache) openStore(readOnly bool) error {
 		}
 	}
 
-	c.fsTree = &fstree.FSTree{
-		Info: fstree.Info{
-			Permissions: os.ModePerm,
-			RootPath:    c.path,
-		},
-		Depth:      1,
-		DirNameLen: 1,
-	}
+	c.fsTree = fstree.New(
+		fstree.WithPath(c.path),
+		fstree.WithPerm(os.ModePerm),
+		fstree.WithDepth(1),
+		fstree.WithDirNameLen(1),
+		fstree.WithNoSync(c.noSync))
 
 	// Write-cache can be opened multiple times during `SetMode`.
 	// flushed map must not be re-created in this case.