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f4ca94d13b
Before this patch, `compressor` is designed to be a proper abstract class, where the creator of a compressor doesn't even know what he's creating -- he passes a name, and it gets turned into a `compressor` behind a scenes. But later, when creation of compressors will involve looking up dictionaries, this abstraction will only get in the way. So we give up on keeping `compressor` abstract, and instead of using "opaque" names we turn to an explicit enum of possible compressor types. The main point of this patch is to add the `algorithm` enum and the `algorithm_to_name()` function. The rest of the patch switches the `compressor::name()` function to use `algorithm_to_name()` instead of the passed-by-constructor `compressor::_name`, to keep a single source of truth for the names.
119 lines
3.7 KiB
C++
119 lines
3.7 KiB
C++
/*
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* Copyright (C) 2015-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include <map>
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#include <optional>
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#include <set>
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#include <seastar/core/future.hh>
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#include <seastar/core/shared_ptr.hh>
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#include <seastar/core/sstring.hh>
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#include "seastarx.hh"
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class compressor {
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public:
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enum class algorithm {
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lz4,
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zstd,
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snappy,
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deflate,
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none,
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};
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virtual ~compressor() {}
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/**
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* Unpacks data in "input" to output. If output_len is of insufficient size,
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* exception is thrown. I.e. you should keep track of the uncompressed size.
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*/
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virtual size_t uncompress(const char* input, size_t input_len, char* output,
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size_t output_len) const = 0;
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/**
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* Packs data in "input" to output. If output_len is of insufficient size,
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* exception is thrown. Maximum required size is obtained via "compress_max_size"
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*/
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virtual size_t compress(const char* input, size_t input_len, char* output,
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size_t output_len) const = 0;
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/**
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* Returns the maximum output size for compressing data on "input_len" size.
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*/
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virtual size_t compress_max_size(size_t input_len) const = 0;
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/**
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* Returns accepted option names for this compressor
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*/
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virtual std::set<sstring> option_names() const;
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/**
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* Returns original options used in instantiating this compressor
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*/
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virtual std::map<sstring, sstring> options() const;
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std::string name() const;
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virtual algorithm get_algorithm() const = 0;
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// to cheaply bridge sstable compression options / maps
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using opt_string = std::optional<sstring>;
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using opt_getter = std::function<opt_string(const sstring&)>;
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using ptr_type = shared_ptr<compressor>;
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static ptr_type create(const sstring& name, const opt_getter&);
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static ptr_type create(const std::map<sstring, sstring>&);
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static thread_local const ptr_type lz4;
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static thread_local const ptr_type snappy;
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static thread_local const ptr_type deflate;
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};
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template<typename BaseType, typename... Args>
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class class_registry;
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using compressor_ptr = compressor::ptr_type;
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using compressor_registry = class_registry<compressor, const typename compressor::opt_getter&>;
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class compression_parameters {
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public:
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using algorithm = compressor::algorithm;
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static constexpr std::string_view name_prefix = "org.apache.cassandra.io.compress.";
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static constexpr int32_t DEFAULT_CHUNK_LENGTH = 4 * 1024;
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static constexpr double DEFAULT_CRC_CHECK_CHANCE = 1.0;
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static const sstring SSTABLE_COMPRESSION;
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static const sstring CHUNK_LENGTH_KB;
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static const sstring CHUNK_LENGTH_KB_ERR;
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static const sstring CRC_CHECK_CHANCE;
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private:
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compressor_ptr _compressor;
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std::optional<int> _chunk_length;
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std::optional<double> _crc_check_chance;
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public:
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compression_parameters();
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compression_parameters(compressor_ptr);
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compression_parameters(const std::map<sstring, sstring>& options);
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~compression_parameters();
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compressor_ptr get_compressor() const { return _compressor; }
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int32_t chunk_length() const { return _chunk_length.value_or(int(DEFAULT_CHUNK_LENGTH)); }
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double crc_check_chance() const { return _crc_check_chance.value_or(double(DEFAULT_CRC_CHECK_CHANCE)); }
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void validate();
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std::map<sstring, sstring> get_options() const;
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bool operator==(const compression_parameters& other) const;
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static compression_parameters no_compression() {
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return compression_parameters(nullptr);
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}
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static std::string_view algorithm_to_name(algorithm);
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static std::string algorithm_to_qualified_name(algorithm);
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private:
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void validate_options(const std::map<sstring, sstring>&);
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};
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