rocksdb/db/blob/blob_log_format.h
Levi Tamasi 9b083cb11c Build blob file reader/writer classes in LITE mode as well (#7272)
Summary:
The patch makes sure that the functionality required for the new integrated
BlobDB implementation (most importantly, the classes related to reading and
writing blob files) is also built in LITE mode by removing the corresponding
`#ifndef`s.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7272

Test Plan: Ran `make check` in both regular and LITE mode.

Reviewed By: zhichao-cao

Differential Revision: D23173280

Pulled By: ltamasi

fbshipit-source-id: 1596bd1a76409a8a6d83d8f1dbfe08bfdea7ffe6
2020-08-17 15:19:05 -07:00

127 lines
4.3 KiB
C++

// 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
#include <memory>
#include <utility>
#include "rocksdb/options.h"
#include "rocksdb/slice.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
namespace ROCKSDB_NAMESPACE {
constexpr uint32_t kMagicNumber = 2395959; // 0x00248f37
constexpr uint32_t kVersion1 = 1;
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 ROCKSDB_NAMESPACE