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

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

pkg/local_object_storage/writecache/writecachebadger/get.go

@@ -0,0 +1,95 @@
+package writecachebadger
+
+import (
+	"context"
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
+	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"github.com/dgraph-io/badger/v4"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Get returns object from write-cache.
+//
+// Returns an error of type apistatus.ObjectNotFound if the requested object is missing in write-cache.
+func (c *cache) Get(ctx context.Context, addr oid.Address) (*objectSDK.Object, error) {
+	_, span := tracing.StartSpanFromContext(ctx, "writecache.Get",
+		trace.WithAttributes(
+			attribute.String("address", addr.EncodeToString()),
+		))
+	defer span.End()
+
+	obj, err := c.getInternal(addr)
+	return obj, metaerr.Wrap(err)
+}
+
+func (c *cache) getInternal(addr oid.Address) (*objectSDK.Object, error) {
+	found := false
+	storageType := writecache.StorageTypeUndefined
+	startedAt := time.Now()
+	defer func() {
+		c.metrics.Get(time.Since(startedAt), found, storageType)
+	}()
+
+	k := addr2key(addr)
+	value, err := Get(c.db, k[:])
+	if err == nil {
+		obj := objectSDK.New()
+		found = true
+		storageType = writecache.StorageTypeDB
+		return obj, obj.Unmarshal(value)
+	}
+
+	return nil, logicerr.Wrap(apistatus.ObjectNotFound{})
+}
+
+// Head returns object header from write-cache.
+//
+// Returns an error of type apistatus.ObjectNotFound if the requested object is missing in write-cache.
+func (c *cache) Head(ctx context.Context, addr oid.Address) (*objectSDK.Object, error) {
+	_, span := tracing.StartSpanFromContext(ctx, "writecache.Head",
+		trace.WithAttributes(
+			attribute.String("address", addr.EncodeToString()),
+		))
+	defer span.End()
+
+	obj, err := c.getInternal(addr)
+	if err != nil {
+		return nil, metaerr.Wrap(err)
+	}
+
+	return obj.CutPayload(), nil
+}
+
+// Get fetches object from the underlying database.
+// Key should be a stringified address.
+//
+// Returns an error of type apistatus.ObjectNotFound if the requested object is missing in db.
+func Get(db *badger.DB, key []byte) ([]byte, error) {
+	var value []byte
+
+	err := db.View(func(tx *badger.Txn) error {
+		it, err := tx.Get(key)
+		if err != nil {
+			if err == badger.ErrKeyNotFound {
+				return logicerr.Wrap(apistatus.ObjectNotFound{})
+			}
+			return err
+		}
+		v, err := it.ValueCopy(nil)
+		if err != nil {
+			return err
+		}
+		value = v
+		return nil
+	})
+
+	return value, metaerr.Wrap(err)
+}