[#421] Try using badger for the write-cache

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

pkg/local_object_storage/writecache/writecachebadger/storage.go

@@ -0,0 +1,91 @@
+package writecachebadger
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
+	storagelog "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/log"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"github.com/dgraph-io/badger/v4"
+	"go.uber.org/zap"
+)
+
+// store represents persistent storage with in-memory LRU cache
+// for flushed items on top of it.
+type store struct {
+	db *badger.DB
+}
+
+type internalKey [len(cid.ID{}) + len(oid.ID{})]byte
+
+func (k internalKey) address() oid.Address {
+	var addr oid.Address
+	var cnr cid.ID
+	var obj oid.ID
+	copy(cnr[:], k[:len(cnr)])
+	copy(obj[:], k[len(cnr):])
+	addr.SetContainer(cnr)
+	addr.SetObject(obj)
+	return addr
+}
+
+func addr2key(addr oid.Address) internalKey {
+	var key internalKey
+	cnr, obj := addr.Container(), addr.Object()
+	copy(key[:len(cnr)], cnr[:])
+	copy(key[len(cnr):], obj[:])
+	return key
+}
+
+const dbName = "small.badger"
+
+func (c *cache) openStore(readOnly bool) error {
+	err := util.MkdirAllX(c.path, os.ModePerm)
+	if err != nil {
+		return err
+	}
+
+	c.db, err = OpenDB(filepath.Join(c.path, dbName), readOnly, c.log)
+	if err != nil {
+		return fmt.Errorf("could not open database: %w", err)
+	}
+
+	return nil
+}
+
+func (c *cache) deleteFromDB(keys []string) []string {
+	if len(keys) == 0 {
+		return keys
+	}
+
+	wb := c.db.NewWriteBatch()
+
+	var errorIndex int
+	for errorIndex = range keys {
+		if err := wb.Delete([]byte(keys[errorIndex])); err != nil {
+			break
+		}
+	}
+
+	for i := 0; i < errorIndex; i++ {
+		c.objCounters.DecDB()
+		c.metrics.Evict(writecache.StorageTypeDB)
+		storagelog.Write(c.log,
+			storagelog.AddressField(keys[i]),
+			storagelog.StorageTypeField(wcStorageType),
+			storagelog.OpField("db DELETE"),
+		)
+	}
+
+	if err := wb.Flush(); err != nil {
+		c.log.Error(logs.WritecacheCantRemoveObjectsFromTheDatabase, zap.Error(err))
+	}
+
+	copy(keys, keys[errorIndex:])
+	return keys[:len(keys)-errorIndex]
+}