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/*
* Copyright 2003-2021 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_BLOCKING_NFS_CALLBACK_HXX
#define MPD_BLOCKING_NFS_CALLBACK_HXX
#include "Callback.hxx"
#include "Lease.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include <exception>
class NfsConnection;
/**
* Utility class to implement a blocking NFS call using the libnfs
* async API. The actual method call is deferred to the #EventLoop
* thread, and method Run() waits for completion.
*/
class BlockingNfsOperation : protected NfsCallback, NfsLease {
static constexpr std::chrono::steady_clock::duration timeout =
std::chrono::minutes(1);
Mutex mutex;
Cond cond;
bool finished;
std::exception_ptr error;
protected:
NfsConnection &connection;
public:
BlockingNfsOperation(NfsConnection &_connection) noexcept
:finished(false), connection(_connection) {}
/**
* Throws std::runtime_error on error.
*/
void Run();
private:
bool LockWaitFinished() noexcept {
std::unique_lock<Mutex> lock(mutex);
return cond.wait_for(lock, timeout, [this]{ return finished; });
}
/**
* Mark the operation as "finished" and wake up the waiting
* thread.
*/
void LockSetFinished() noexcept {
const std::scoped_lock<Mutex> protect(mutex);
finished = true;
cond.notify_one();
}
/* 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;
protected:
virtual void Start() = 0;
virtual void HandleResult(unsigned status, void *data) noexcept = 0;
};
#endif