[#176] localstore: Implement primary BlobStor

Implement primary local BLOB storage based on filesystem tree.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/local_object_storage/blobstor/compress.go

@@ -0,0 +1,35 @@
+package blobstor
+
+import (
+	"github.com/klauspost/compress/zstd"
+)
+
+func noOpCompressor(data []byte) []byte {
+	return data
+}
+
+func noOpDecompressor(data []byte) ([]byte, error) {
+	return data, nil
+}
+
+func zstdCompressor() func([]byte) []byte {
+	enc, err := zstd.NewWriter(nil)
+	if err != nil {
+		panic(err)
+	}
+
+	return func(data []byte) []byte {
+		return enc.EncodeAll(data, make([]byte, 0, len(data)))
+	}
+}
+
+func zstdDecompressor() func([]byte) ([]byte, error) {
+	dec, err := zstd.NewReader(nil)
+	if err != nil {
+		panic(err)
+	}
+
+	return func(data []byte) ([]byte, error) {
+		return dec.DecodeAll(data, nil)
+	}
+}