rocksdb/include/rocksdb/file_checksum.h
mrambacher 524b10bd6e Fix spelling in comments in include/rocksdb/ (#8120)
Summary:
Ran a spell check over the comments in the include/rocksdb directory and fixed any mis-spellings.

There are still some variable names that are spelled incorrectly (like SizeApproximationOptions::include_memtabtles, SstFileMetaData::oldest_ancester_time) that were not fixed, as those would break compilation.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8120

Reviewed By: zhichao-cao

Differential Revision: D27366034

Pulled By: mrambacher

fbshipit-source-id: 6a3f3674890bb6acc751e9c5887a8fbb6adca5df
2021-03-29 05:05:06 -07:00

130 lines
5.0 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).
// Copyright (c) 2013 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <cassert>
#include <map>
#include <memory>
#include <string>
#include <vector>
#include "rocksdb/status.h"
namespace ROCKSDB_NAMESPACE {
// The unknown file checksum.
constexpr char kUnknownFileChecksum[] = "";
// The unknown sst file checksum function name.
constexpr char kUnknownFileChecksumFuncName[] = "Unknown";
// The standard DB file checksum function name.
// This is the name of the checksum function returned by
// GetFileChecksumGenCrc32cFactory();
constexpr char kStandardDbFileChecksumFuncName[] = "FileChecksumCrc32c";
struct FileChecksumGenContext {
std::string file_name;
// The name of the requested checksum generator.
// Checksum factories may use or ignore requested_checksum_func_name,
// and checksum factories written before this field was available are still
// compatible.
std::string requested_checksum_func_name;
};
// FileChecksumGenerator is the class to generates the checksum value
// for each file when the file is written to the file system.
// Implementations may assume that
// * Finalize is called at most once during the life of the object
// * All calls to Update come before Finalize
// * All calls to GetChecksum come after Finalize
class FileChecksumGenerator {
public:
virtual ~FileChecksumGenerator() {}
// Update the current result after process the data. For different checksum
// functions, the temporal results may be stored and used in Update to
// include the new data.
virtual void Update(const char* data, size_t n) = 0;
// Generate the final results if no further new data will be updated.
virtual void Finalize() = 0;
// Get the checksum. The result should not be the empty string and may
// include arbitrary bytes, including non-printable characters.
virtual std::string GetChecksum() const = 0;
// Returns a name that identifies the current file checksum function.
virtual const char* Name() const = 0;
};
// Create the FileChecksumGenerator object for each SST file.
class FileChecksumGenFactory {
public:
virtual ~FileChecksumGenFactory() {}
// Create a new FileChecksumGenerator.
virtual std::unique_ptr<FileChecksumGenerator> CreateFileChecksumGenerator(
const FileChecksumGenContext& context) = 0;
// Return the name of this FileChecksumGenFactory.
virtual const char* Name() const = 0;
};
// FileChecksumList stores the checksum information of a list of files (e.g.,
// SST files). The FileChecksumList can be used to store the checksum
// information of all SST file getting from the MANIFEST, which are
// the checksum information of all valid SST file of a DB instance. It can
// also be used to store the checksum information of a list of SST files to
// be ingested.
class FileChecksumList {
public:
virtual ~FileChecksumList() {}
// Clean the previously stored file checksum information.
virtual void reset() = 0;
// Get the number of checksums in the checksum list
virtual size_t size() const = 0;
// Return all the file checksum information being stored in a unordered_map.
// File_number is the key, the first part of the value is checksum value,
// and the second part of the value is checksum function name.
virtual Status GetAllFileChecksums(
std::vector<uint64_t>* file_numbers, std::vector<std::string>* checksums,
std::vector<std::string>* checksum_func_names) = 0;
// Given the file_number, it searches if the file checksum information is
// stored.
virtual Status SearchOneFileChecksum(uint64_t file_number,
std::string* checksum,
std::string* checksum_func_name) = 0;
// Insert the checksum information of one file to the FileChecksumList.
virtual Status InsertOneFileChecksum(
uint64_t file_number, const std::string& checksum,
const std::string& checksum_func_name) = 0;
// Remove the checksum information of one SST file.
virtual Status RemoveOneFileChecksum(uint64_t file_number) = 0;
};
// Create a new file checksum list.
extern FileChecksumList* NewFileChecksumList();
// Return a shared_ptr of the builtin Crc32c based file checksum generator
// factory object, which can be shared to create the Crc32c based checksum
// generator object.
// Note: this implementation is compatible with many other crc32c checksum
// implementations and uses big-endian encoding of the result, unlike most
// other crc32c checksums in RocksDB, which alter the result with
// crc32c::Mask and use little-endian encoding.
extern std::shared_ptr<FileChecksumGenFactory>
GetFileChecksumGenCrc32cFactory();
} // namespace ROCKSDB_NAMESPACE