ardupilot/libraries/AP_HAL_Linux/Poller.h

128 lines
3.2 KiB
C
Raw Normal View History

/*
* Copyright (C) 2016 Intel Corporation. All rights reserved.
*
* This file 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 3 of the License, or
* (at your option) any later version.
*
* This file 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, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <unistd.h>
#include "AP_HAL/utility/RingBuffer.h"
#include "Semaphores.h"
namespace Linux {
class Poller;
class Pollable {
friend class Poller;
public:
Pollable(int fd) : _fd(fd) { }
Pollable() { }
virtual ~Pollable();
int get_fd() const { return _fd; }
/* Called whenever the underlying file descriptor has data to be read. */
virtual void on_can_read() { }
/*
* Called whenever the underlying file descriptor is ready to receive new
* data, i.e. its buffer is not full.
*/
virtual void on_can_write() { }
/*
* Called when an error occurred and is signaled by the OS - its meaning
* depends on the file descriptor being used.
*/
virtual void on_error() { }
/*
* Called when the other side closes its end - the exact meaning
* depends on the file descriptor being used.
*/
virtual void on_hang_up() { }
protected:
int _fd = -1;
};
/*
* Internal class to be used inside Poller in order to keep track of requests
* to wake it up
*/
class WakeupPollable : public Pollable {
friend class Poller;
public:
void on_can_read() override;
};
class Poller {
public:
Poller();
~Poller() {
unregister_pollable(&_wakeup);
if (_epfd >= 0) {
close(_epfd);
}
}
/*
* Check if this Poller is not initialized
*/
bool operator!() const { return _epfd == -1; }
/*
* Check if this Poller is succesfully initialized
*/
explicit operator bool() const { return _epfd != -1; }
/*
* Register @p in this poller so calls to poll() will wait for
* events specified in @events argument.
*/
bool register_pollable(Pollable *p, uint32_t events);
/*
* Unregister @p from this Poller so it doesn't generate any more
* event. Note that this doesn't destroy @p.
*/
void unregister_pollable(const Pollable *p);
/*
* Wait for events on all Pollable objects registered with
* register_pollable(). New Pollable objects can be registered at any
* time, including when a thread is sleeping on a poll() call.
*/
int poll() const;
/*
* Wake up the thread sleeping on a poll() call if it is in fact
* sleeping. Otherwise a nop event is generated and handled. This is
* usually called from a thread different from the one calling poll().
*/
void wakeup() const;
private:
int _epfd = -1;
WakeupPollable _wakeup{};
};
}