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