478c1eaec5
Add a new reader that wraps file_random_access_reader and computes a running CRC32 digest over the data as it is read. The digest accumulates across sequential read_exactly() calls and is reset on seek(), since a non-sequential read invalidates the running checksum.
79 lines
2.0 KiB
C++
79 lines
2.0 KiB
C++
/*
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* Copyright (C) 2018-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 "exceptions.hh"
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#include <memory>
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#include <seastar/core/file.hh>
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#include <seastar/core/fstream.hh>
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#include <seastar/core/future.hh>
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#include <seastar/core/gate.hh>
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#include <seastar/core/iostream.hh>
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#include <seastar/core/temporary_buffer.hh>
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#include "seastarx.hh"
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#include "sstables/checksum_utils.hh"
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namespace sstables {
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class random_access_reader {
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std::unique_ptr <input_stream<char>> _in;
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protected:
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virtual input_stream<char> open_at(uint64_t pos) = 0;
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void set(input_stream<char> in) {
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parse_assert(!_in);
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_in = std::make_unique<input_stream<char>>(std::move(in));
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}
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public:
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virtual future <temporary_buffer<char>> read_exactly(size_t n) noexcept;
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virtual future<> seek(uint64_t pos) noexcept;
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bool eof() const noexcept { return _in->eof(); }
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virtual future<> close() noexcept;
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virtual ~random_access_reader() {}
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};
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class file_random_access_reader : public random_access_reader {
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file _file;
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size_t _buffer_size;
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unsigned _read_ahead;
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protected:
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uint64_t _file_size;
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public:
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virtual input_stream<char> open_at(uint64_t pos) override;
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explicit file_random_access_reader(file f, uint64_t file_size, size_t buffer_size = 8192, unsigned read_ahead = 4);
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virtual future<> close() noexcept override;
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};
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class digest_file_random_access_reader : public file_random_access_reader {
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std::optional<uint32_t> _digest;
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uint64_t _pos = 0;
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public:
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digest_file_random_access_reader(file f, uint64_t file_size, size_t buffer_size = 8192, unsigned read_ahead = 4);
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virtual future<temporary_buffer<char>> read_exactly(size_t n) noexcept override;
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virtual future<> seek(uint64_t pos) noexcept override;
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std::optional<uint32_t> digest() const noexcept {
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if (_pos != _file_size) {
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return std::nullopt;
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}
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return _digest;
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}
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};
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}
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