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/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_NFS_FILE_READER_HXX
#define MPD_NFS_FILE_READER_HXX
#include "check.h"
#include "Lease.hxx"
#include "Callback.hxx"
#include "event/DeferEvent.hxx"
#include "util/Compiler.h"
#include <string>
#include <exception>
#include <stdint.h>
#include <stddef.h>
#include <sys/stat.h>
struct nfsfh;
class NfsConnection;
/**
* A helper class which helps with reading from a file. It obtains a
* connection lease (#NfsLease), opens the given file, "stats" the
* file, and finally allos you to read its contents.
*
* To get started, derive your class from it and implement the pure
* virtual methods, construct an instance, and call Open().
*/
class NfsFileReader : NfsLease, NfsCallback {
enum class State {
INITIAL,
DEFER,
MOUNT,
OPEN,
STAT,
READ,
IDLE,
};
State state = State::INITIAL;
std::string server, export_name;
const char *path;
NfsConnection *connection;
nfsfh *fh;
DeferEvent defer_open;
public:
NfsFileReader() noexcept;
~NfsFileReader() noexcept;
EventLoop &GetEventLoop() noexcept {
return defer_open.GetEventLoop();
}
void Close() noexcept;
void DeferClose() noexcept;
/**
* Open the file. This method is thread-safe.
*
* Throws std::runtime_error on error.
*/
void Open(const char *uri);
/**
* Attempt to read from the file. This may only be done after
* OnNfsFileOpen() has been called. Only one read operation
* may be performed at a time.
*
* This method is not thread-safe and must be called from
* within the I/O thread.
*
* Throws std::runtime_error on error.
*/
void Read(uint64_t offset, size_t size);
/**
* Cancel the most recent Read() call.
*
* This method is not thread-safe and must be called from
* within the I/O thread.
*/
void CancelRead() noexcept;
bool IsIdle() const noexcept {
return state == State::IDLE;
}
protected:
/**
* The file has been opened successfully. It is a regular
* file, and its size is known. It is ready to be read from
* using Read().
*
* This method will be called from within the I/O thread.
*/
virtual void OnNfsFileOpen(uint64_t size) noexcept = 0;
/**
* A Read() has completed successfully.
*
* This method will be called from within the I/O thread.
*/
virtual void OnNfsFileRead(const void *data, size_t size) noexcept = 0;
/**
* An error has occurred, which can be either while waiting
* for OnNfsFileOpen(), or while waiting for OnNfsFileRead(),
* or if disconnected while idle.
*/
virtual void OnNfsFileError(std::exception_ptr &&e) noexcept = 0;
private:
/**
* Cancel the current operation, if any. The NfsLease must be
* unregistered already.
*/
void CancelOrClose() noexcept;
void OpenCallback(nfsfh *_fh) noexcept;
void StatCallback(const struct stat *st) noexcept;
/* virtual methods from NfsLease */
void OnNfsConnectionReady() noexcept final;
void OnNfsConnectionFailed(std::exception_ptr e) noexcept final;
void OnNfsConnectionDisconnected(std::exception_ptr e) noexcept final;
/* virtual methods from NfsCallback */
void OnNfsCallback(unsigned status, void *data) noexcept final;
void OnNfsError(std::exception_ptr &&e) noexcept final;
/* DeferEvent callback */
void OnDeferredOpen() noexcept;
};
#endif
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