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compress.hh
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compress.hh
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/*
* Copyright (C) 2015-present ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <map>
#include <set>
#include <seastar/core/future.hh>
#include <seastar/core/shared_ptr.hh>
#include <seastar/core/sstring.hh>
#include "exceptions/exceptions.hh"
class compressor {
sstring _name;
public:
compressor(sstring);
virtual ~compressor() {}
/**
* Unpacks data in "input" to output. If output_len is of insufficient size,
* exception is thrown. I.e. you should keep track of the uncompressed size.
*/
virtual size_t uncompress(const char* input, size_t input_len, char* output,
size_t output_len) const = 0;
/**
* Packs data in "input" to output. If output_len is of insufficient size,
* exception is thrown. Maximum required size is obtained via "compress_max_size"
*/
virtual size_t compress(const char* input, size_t input_len, char* output,
size_t output_len) const = 0;
/**
* Returns the maximum output size for compressing data on "input_len" size.
*/
virtual size_t compress_max_size(size_t input_len) const = 0;
/**
* Returns accepted option names for this compressor
*/
virtual std::set<sstring> option_names() const;
/**
* Returns original options used in instantiating this compressor
*/
virtual std::map<sstring, sstring> options() const;
/**
* Compressor class name.
*/
const sstring& name() const {
return _name;
}
// to cheaply bridge sstable compression options / maps
using opt_string = std::optional<sstring>;
using opt_getter = std::function<opt_string(const sstring&)>;
using ptr_type = shared_ptr<compressor>;
static ptr_type create(const sstring& name, const opt_getter&);
static ptr_type create(const std::map<sstring, sstring>&);
static thread_local const ptr_type lz4;
static thread_local const ptr_type snappy;
static thread_local const ptr_type deflate;
static const sstring namespace_prefix;
};
template<typename BaseType, typename... Args>
class class_registry;
using compressor_ptr = compressor::ptr_type;
using compressor_registry = class_registry<compressor, const typename compressor::opt_getter&>;
class compression_parameters {
public:
static constexpr int32_t DEFAULT_CHUNK_LENGTH = 4 * 1024;
static constexpr double DEFAULT_CRC_CHECK_CHANCE = 1.0;
static const sstring SSTABLE_COMPRESSION;
static const sstring CHUNK_LENGTH_KB;
static const sstring CHUNK_LENGTH_KB_ERR;
static const sstring CRC_CHECK_CHANCE;
private:
compressor_ptr _compressor;
std::optional<int> _chunk_length;
std::optional<double> _crc_check_chance;
public:
compression_parameters();
compression_parameters(compressor_ptr);
compression_parameters(const std::map<sstring, sstring>& options);
~compression_parameters();
compressor_ptr get_compressor() const { return _compressor; }
int32_t chunk_length() const { return _chunk_length.value_or(int(DEFAULT_CHUNK_LENGTH)); }
double crc_check_chance() const { return _crc_check_chance.value_or(double(DEFAULT_CRC_CHECK_CHANCE)); }
void validate();
std::map<sstring, sstring> get_options() const;
bool operator==(const compression_parameters& other) const;
bool operator!=(const compression_parameters& other) const;
static compression_parameters no_compression() {
return compression_parameters(nullptr);
}
private:
void validate_options(const std::map<sstring, sstring>&);
};