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/*
* Copyright (c) 2020-2021 Vasile Vilvoiu <vasi@vilvoiu.ro>
*
* specgram is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#ifndef _INPUT_READER_HPP_
#define _INPUT_READER_HPP_
#include <istream>
#include <mutex>
#include <optional>
#include <thread>
#include <vector>
/*
* Input reader base class
*/
class InputReader {
protected:
std::istream * const stream_;
const std::size_t block_size_bytes_;
virtual std::vector<char> GetBuffer() = 0;
public:
InputReader() = delete;
InputReader(const InputReader&) = delete;
InputReader(InputReader&&) = delete;
InputReader & operator=(const InputReader&) = delete;
InputReader(std::istream * stream, std::size_t block_size_bytes);
virtual ~InputReader() = default;
virtual bool ReachedEOF() const = 0;
virtual std::optional<std::vector<char>> GetBlock() = 0;
};
/*
* Synchronous input reader
*/
class SyncInputReader : public InputReader {
protected:
std::vector<char> GetBuffer() override;
public:
SyncInputReader(std::istream * stream, std::size_t block_size_bytes);
bool ReachedEOF() const override;
std::optional<std::vector<char>> GetBlock() override;
};
/*
* Asynchronous input reader
*/
class AsyncInputReader : public InputReader {
private:
/* buffer where we read up until one block */
volatile char *buffer_;
volatile std::size_t bytes_in_buffer_;
/* mutex for accessing buffer */
std::mutex mutex_;
/* thread for reading from input stream */
std::thread reader_thread_;
volatile bool running_;
void Read();
protected:
std::vector<char> GetBuffer() override;
public:
AsyncInputReader(std::istream * stream, std::size_t block_size_bytes);
~AsyncInputReader() override;
bool ReachedEOF() const override;
std::optional<std::vector<char>> GetBlock() override;
};
#endif
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