Line data    Source code

       1             : /*
       2             :  * Copyright (C) 2016  Intel Corporation. All rights reserved.
       3             :  *
       4             :  * This file is free software: you can redistribute it and/or modify it
       5             :  * under the terms of the GNU General Public License as published by the
       6             :  * Free Software Foundation, either version 3 of the License, or
       7             :  * (at your option) any later version.
       8             :  *
       9             :  * This file is distributed in the hope that it will be useful, but
      10             :  * WITHOUT ANY WARRANTY; without even the implied warranty of
      11             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
      12             :  * See the GNU General Public License for more details.
      13             :  *
      14             :  * You should have received a copy of the GNU General Public License along
      15             :  * with this program.  If not, see <http://www.gnu.org/licenses/>.
      16             :  */
      17             : #pragma once
      18             : 
      19             : #include <unistd.h>
      20             : 
      21             : #include "AP_HAL/utility/RingBuffer.h"
      22             : #include "Semaphores.h"
      23             : 
      24             : namespace Linux {
      25             : 
      26             : class Poller;
      27             : 
      28             : class Pollable {
      29             :     friend class Poller;
      30             : public:
      31             :     Pollable(int fd) : _fd(fd) { }
      32           1 :     Pollable() { }
      33             : 
      34             :     virtual ~Pollable();
      35             : 
      36           4 :     int get_fd() const { return _fd; }
      37             : 
      38             :     /* Called whenever the underlying file descriptor has data to be read. */
      39           0 :     virtual void on_can_read() { }
      40             : 
      41             :     /*
      42             :      * Called whenever the underlying file descriptor is ready to receive new
      43             :      * data, i.e. its buffer is not full.
      44             :      */
      45           0 :     virtual void on_can_write() { }
      46             : 
      47             :     /*
      48             :      * Called when an error occurred and is signaled by the OS - its meaning
      49             :      * depends on the file descriptor being used.
      50             :      */
      51           0 :     virtual void on_error() { }
      52             : 
      53             :     /*
      54             :      * Called when the other side closes its end - the exact meaning
      55             :      * depends on the file descriptor being used.
      56             :      */
      57           0 :     virtual void on_hang_up() { }
      58             : 
      59             : protected:
      60             :     int _fd = -1;
      61             : };
      62             : 
      63             : /*
      64             :  * Internal class to be used inside Poller in order to keep track of requests
      65             :  * to wake it up
      66             :  */
      67             : class WakeupPollable : public Pollable {
      68             :     friend class Poller;
      69             : public:
      70             :     void on_can_read() override;
      71             : };
      72             : 
      73             : class Poller {
      74             : public:
      75             :     Poller();
      76             : 
      77           1 :     ~Poller() {
      78           1 :         unregister_pollable(&_wakeup);
      79             : 
      80           1 :         if (_epfd >= 0) {
      81           1 :             close(_epfd);
      82             :         }
      83           1 :     }
      84             : 
      85             :     /*
      86             :      * Check if this Poller is not initialized
      87             :      */
      88           2 :     bool operator!() const { return _epfd == -1; }
      89             : 
      90             :     /*
      91             :      * Check if this Poller is succesfully initialized
      92             :      */
      93             :     explicit operator bool() const { return _epfd != -1; }
      94             : 
      95             :     /*
      96             :      * Register @p in this poller so calls to poll() will wait for
      97             :      * events specified in @events argument.
      98             :      */
      99             :     bool register_pollable(Pollable *p, uint32_t events);
     100             : 
     101             :     /*
     102             :      * Unregister @p from this Poller so it doesn't generate any more
     103             :      * event. Note that this doesn't destroy @p.
     104             :      */
     105             :     void unregister_pollable(const Pollable *p);
     106             : 
     107             :     /*
     108             :      * Wait for events on all Pollable objects registered with
     109             :      * register_pollable(). New Pollable objects can be registered at any
     110             :      * time, including when a thread is sleeping on a poll() call.
     111             :      */
     112             :     int poll() const;
     113             : 
     114             :     /*
     115             :      * Wake up the thread sleeping on a poll() call if it is in fact
     116             :      * sleeping. Otherwise a nop event is generated and handled. This is
     117             :      * usually called from a thread different from the one calling poll().
     118             :      */
     119             :     void wakeup() const;
     120             : 
     121             : private:
     122             : 
     123             :     int _epfd = -1;
     124             :     WakeupPollable _wakeup{};
     125             : };
     126             : 
     127             : }