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asio-std-file-handler.hpp
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asio-std-file-handler.hpp
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/*
* This file is part of libkazv.
* SPDX-FileCopyrightText: 2021 Tusooa Zhu <tusooa@kazv.moe>
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#pragma once
#include "libkazv-config.hpp"
#include <fstream>
#include <boost/asio.hpp>
#include "file-desc.hpp"
namespace Kazv
{
template<class Exec>
class AsioStdFileStream
{
public:
using DataT = FileContent;
/**
* Constructor.
*
* @param exec A boost::asio executor. It should run actions
* sequentially.
* @param filename The file name of this FileStream.
*/
inline AsioStdFileStream(Exec exec, std::string filename, FileOpenMode mode)
: m_executor(exec)
, m_filename(filename)
, m_mode(mode)
, m_stream(std::make_shared<std::fstream>(
m_filename,
(m_mode == FileOpenMode::Read
? std::ios_base::in
: std::ios_base::out)
| std::ios_base::binary))
{}
inline bool valid() { return !!m_stream; }
template<class Callback>
void read(int maxSize, Callback readCallback) {
boost::asio::post(
m_executor,
[stream=m_stream, maxSize, readCallback=std::move(readCallback)]() {
auto buf = std::vector<char>(maxSize, '\0');
auto data = FileContent{};
auto actualSize = int{};
try {
stream->read(buf.data(), maxSize);
actualSize = stream->gcount();
data = FileContent(buf.begin(), buf.begin() + actualSize);
} catch (const std::exception &) {
readCallback(FileOpRetCode::Error, FileContent{});
return;
}
if (actualSize > 0) {
readCallback(FileOpRetCode::Success, data);
} else if (stream->eof()) {
readCallback(FileOpRetCode::Eof, FileContent{});
} else {
readCallback(FileOpRetCode::Error, FileContent{});
}
});
}
template<class Callback>
void write(DataT data, Callback writeCallback) {
boost::asio::post(
m_executor,
[stream=m_stream, data, writeCallback=std::move(writeCallback)]() {
try {
auto buf = std::vector<char>(data.begin(), data.end());
stream->write(buf.data(), buf.size());
} catch (const std::exception &) {
writeCallback(FileOpRetCode::Error, 0);
return;
}
if (stream->bad()) {
writeCallback(FileOpRetCode::Error, 0);
} else {
writeCallback(FileOpRetCode::Success, data.size());
}
});
}
private:
Exec m_executor;
std::string m_filename;
FileOpenMode m_mode;
std::shared_ptr<std::fstream> m_stream;
};
template<class Exec>
class AsioStdFileProvider
{
public:
using FileStreamT = AsioStdFileStream<Exec>;
/**
* Constructor.
*
* @param exec A boost::asio executor. It should run actions
* sequentially.
* @param filename The file name of this FileProvider.
*/
inline AsioStdFileProvider(Exec exec, std::string filename)
: m_executor(exec)
, m_filename(filename)
{}
/**
* Get the FileStream provided by this.
*
* @return A FileStreamT that is associated with this file.
*/
FileStreamT getStream(FileOpenMode mode) const {
return FileStreamT(m_executor, m_filename, mode);
}
private:
Exec m_executor;
std::string m_filename;
};
template<class Exec>
class AsioStdFileHandler
{
public:
using FileProviderT = AsioStdFileProvider<Exec>;
/**
* Constructor.
*
* @param exec A boost::asio executor. It should run actions
* sequentially.
*/
inline AsioStdFileHandler(Exec exec)
: m_executor(exec)
{}
/**
* Get the FileProvider for `desc`.
*
* @warning You should not call this explicitly.
* It should only be called by `desc.provider(*this)`.
*/
FileProviderT getProviderFor(FileDesc desc) const {
// assert(desc.name())
return FileProviderT(m_executor, desc.name().value());
}
private:
Exec m_executor;
};
template<class Exec>
AsioStdFileHandler(Exec)->AsioStdFileHandler<Exec>;
}

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