mirror of https://github.com/facebook/rocksdb.git
61 lines
2.4 KiB
C++
61 lines
2.4 KiB
C++
// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include <array>
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#include "file/sequence_file_reader.h"
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namespace ROCKSDB_NAMESPACE {
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// A wrapper on top of Env::SequentialFile for reading text lines from a file.
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// Lines are delimited by '\n'. The last line may or may not include a
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// trailing newline. Uses SequentialFileReader internally.
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class LineFileReader {
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private:
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std::array<char, 8192> buf_;
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SequentialFileReader sfr_;
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IOStatus io_status_;
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const char* buf_begin_ = buf_.data();
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const char* buf_end_ = buf_.data();
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size_t line_number_ = 0;
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bool at_eof_ = false;
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public:
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// See SequentialFileReader constructors
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template <typename... Args>
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explicit LineFileReader(Args&&... args)
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: sfr_(std::forward<Args&&>(args)...) {}
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static IOStatus Create(const std::shared_ptr<FileSystem>& fs,
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const std::string& fname, const FileOptions& file_opts,
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std::unique_ptr<LineFileReader>* reader,
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IODebugContext* dbg, RateLimiter* rate_limiter);
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LineFileReader(const LineFileReader&) = delete;
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LineFileReader& operator=(const LineFileReader&) = delete;
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// Reads another line from the file, returning true on success and saving
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// the line to `out`, without delimiter, or returning false on failure. You
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// must check GetStatus() to determine whether the failure was just
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// end-of-file (OK status) or an I/O error (another status).
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// The internal rate limiter will be charged at the specified priority.
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bool ReadLine(std::string* out, Env::IOPriority rate_limiter_priority);
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// Returns the number of the line most recently returned from ReadLine.
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// Return value is unspecified if ReadLine has returned false due to
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// I/O error. After ReadLine returns false due to end-of-file, return
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// value is the last returned line number, or equivalently the total
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// number of lines returned.
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size_t GetLineNumber() const { return line_number_; }
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// Returns any error encountered during read. The error is considered
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// permanent and no retry or recovery is attempted with the same
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// LineFileReader.
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const IOStatus& GetStatus() const { return io_status_; }
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};
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} // namespace ROCKSDB_NAMESPACE
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