1 files changed, 133 insertions, 0 deletions
diff --git a/src/rocksdb/utilities/blob_db/blob_log_format.h b/src/rocksdb/utilities/blob_db/blob_log_format.h
new file mode 100644
index 000000000..26cdf6e71
--- /dev/null
+++ b/src/rocksdb/utilities/blob_db/blob_log_format.h
@@ -0,0 +1,133 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Log format information shared by reader and writer.
+
+#pragma once
+
+#ifndef ROCKSDB_LITE
+
+#include <limits>
+#include <memory>
+#include <utility>
+
+#include "rocksdb/options.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/status.h"
+#include "rocksdb/types.h"
+
+namespace ROCKSDB_NAMESPACE {
+namespace blob_db {
+
+constexpr uint32_t kMagicNumber = 2395959;  // 0x00248f37
+constexpr uint32_t kVersion1 = 1;
+constexpr uint64_t kNoExpiration = std::numeric_limits<uint64_t>::max();
+
+using ExpirationRange = std::pair<uint64_t, uint64_t>;
+
+// Format of blob log file header (30 bytes):
+//
+//    +--------------+---------+---------+-------+-------------+-------------------+
+//    | magic number | version |  cf id  | flags | compression | expiration range  |
+//    +--------------+---------+---------+-------+-------------+-------------------+
+//    |   Fixed32    | Fixed32 | Fixed32 | char  |    char     | Fixed64   Fixed64 |
+//    +--------------+---------+---------+-------+-------------+-------------------+
+//
+// List of flags:
+//   has_ttl: Whether the file contain TTL data.
+//
+// Expiration range in the header is a rough range based on
+// blob_db_options.ttl_range_secs.
+struct BlobLogHeader {
+  static constexpr size_t kSize = 30;
+
+  BlobLogHeader() = default;
+  BlobLogHeader(uint32_t _column_family_id, CompressionType _compression,
+                bool _has_ttl, const ExpirationRange& _expiration_range)
+      : column_family_id(_column_family_id),
+        compression(_compression),
+        has_ttl(_has_ttl),
+        expiration_range(_expiration_range) {}
+
+  uint32_t version = kVersion1;
+  uint32_t column_family_id = 0;
+  CompressionType compression = kNoCompression;
+  bool has_ttl = false;
+  ExpirationRange expiration_range;
+
+  void EncodeTo(std::string* dst);
+
+  Status DecodeFrom(Slice slice);
+};
+
+// Format of blob log file footer (32 bytes):
+//
+//    +--------------+------------+-------------------+------------+
+//    | magic number | blob count | expiration range  | footer CRC |
+//    +--------------+------------+-------------------+------------+
+//    |   Fixed32    |  Fixed64   | Fixed64 + Fixed64 |   Fixed32  |
+//    +--------------+------------+-------------------+------------+
+//
+// The footer will be presented only when the blob file is properly closed.
+//
+// Unlike the same field in file header, expiration range in the footer is the
+// range of smallest and largest expiration of the data in this file.
+struct BlobLogFooter {
+  static constexpr size_t kSize = 32;
+
+  uint64_t blob_count = 0;
+  ExpirationRange expiration_range = std::make_pair(0, 0);
+  uint32_t crc = 0;
+
+  void EncodeTo(std::string* dst);
+
+  Status DecodeFrom(Slice slice);
+};
+
+// Blob record format (32 bytes header + key + value):
+//
+//    +------------+--------------+------------+------------+----------+---------+-----------+
+//    | key length | value length | expiration | header CRC | blob CRC |   key   |   value   |
+//    +------------+--------------+------------+------------+----------+---------+-----------+
+//    |   Fixed64  |   Fixed64    |  Fixed64   |  Fixed32   | Fixed32  | key len | value len |
+//    +------------+--------------+------------+------------+----------+---------+-----------+
+//
+// If file has has_ttl = false, expiration field is always 0, and the blob
+// doesn't has expiration.
+//
+// Also note that if compression is used, value is compressed value and value
+// length is compressed value length.
+//
+// Header CRC is the checksum of (key_len + val_len + expiration), while
+// blob CRC is the checksum of (key + value).
+//
+// We could use variable length encoding (Varint64) to save more space, but it
+// make reader more complicated.
+struct BlobLogRecord {
+  // header include fields up to blob CRC
+  static constexpr size_t kHeaderSize = 32;
+
+  uint64_t key_size = 0;
+  uint64_t value_size = 0;
+  uint64_t expiration = 0;
+  uint32_t header_crc = 0;
+  uint32_t blob_crc = 0;
+  Slice key;
+  Slice value;
+  std::unique_ptr<char[]> key_buf;
+  std::unique_ptr<char[]> value_buf;
+
+  uint64_t record_size() const { return kHeaderSize + key_size + value_size; }
+
+  void EncodeHeaderTo(std::string* dst);
+
+  Status DecodeHeaderFrom(Slice src);
+
+  Status CheckBlobCRC() const;
+};
+
+}  // namespace blob_db
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE