aa126639c0
It will be used not only in sstables.cc but also in helpers for reading sstables in M format. Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
/*
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* Copyright (C) 2018 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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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 "disk-error-handler.hh"
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namespace sstables {
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extern logging::logger sstlog;
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class random_access_reader {
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std::unique_ptr <input_stream<char>> _in;
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seastar::gate _close_gate;
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protected:
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virtual input_stream<char> open_at(uint64_t pos) = 0;
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public:
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future <temporary_buffer<char>> read_exactly(size_t n) {
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return _in->read_exactly(n);
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}
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void seek(uint64_t pos) {
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if (_in) {
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seastar::with_gate(_close_gate, [in = std::move(_in)]() mutable {
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auto fut = in->close();
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return fut.then([in = std::move(in)] {});
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});
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}
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_in = std::make_unique < input_stream < char >> (open_at(pos));
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}
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bool eof() { return _in->eof(); }
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virtual future<> close() {
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return _close_gate.close().then([this] {
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return _in->close();
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});
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}
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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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uint64_t _file_size;
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size_t _buffer_size;
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unsigned _read_ahead;
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public:
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virtual input_stream<char> open_at(uint64_t pos) override {
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auto len = _file_size - pos;
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file_input_stream_options options;
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options.buffer_size = _buffer_size;
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options.read_ahead = _read_ahead;
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return make_file_input_stream(_file, pos, len, std::move(options));
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}
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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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: _file(std::move(f)), _file_size(file_size), _buffer_size(buffer_size), _read_ahead(read_ahead) {
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seek(0);
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}
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virtual future<> close() override {
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return random_access_reader::close().finally([this] {
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return _file.close().handle_exception([save = _file](auto ep) {
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sstlog.warn("sstable close failed: {}", ep);
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general_disk_error();
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});
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});
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}
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};
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} |