beacon/event_loop.hpp

   1 /**
   2  * beacon
   3  * Author: Lukas Krejci <krejci.l@centrum.cz>, (C) 2008
   4  * Copyright: See COPYING file that comes with this distribution
   5  */
   6
   7 #ifndef BEACON_EVENT_LOOP_H
   8 #define BEACON_EVENT_LOOP_H
   9
  10 #include <beacon/event_queue.hpp>
  11
  12 #include <boost/thread.hpp>
  13 #include <boost/bind.hpp>
  14
  15 namespace beacon {
  16
  17 /**
  18  * Event loop is a wrapper of event_queue that implements
  19  * a simple event queue. I.e. it starts a thread in which
  20  * all the events are invoked.
  21  */
  22 class event_loop : public event_queue {
  23 public:
  24
  25     /**
  26      * A new thread is started to handle this event loop.
  27      */
  28     event_loop() :
  29                _thread(0),
  30                _running(false),
  31                _finished(false)
  32     {}
  33
  34     /**
  35      * This call does NOT block until the underlying thread finishes.
  36      * It just destroys the event_loop object without stopping
  37      * the underlying thread. Be sure to call @link join method before
  38      * the event_loop is destroyed.
  39      */
  40     ~event_loop() {
  41         if (_thread) delete _thread;
  42     }
  43
  44     /**
  45      * Starts the event loop. The events can be enqueued and dequeued before
  46      * the event loop is started but they won't be processed until it is.
  47      *
  48      * This method has no effect if there already is a thread running and
  49      * IS NOT thread-safe.
  50      */
  51     void start() {
  52         if (_thread == 0) {
  53             _running = true;
  54             _finished = false;
  55             _thread = new boost::thread(boost::bind(&event_loop::run, this));
  56         }
  57     }
  58
  59     /**
  60      * Joins the event loop thread. If the thread is started using the {@link start} method
  61      * while another thread is executing this method, the result is undefined.
  62      *
  63      * This method IS NOT thread-safe.
  64      */
  65     void join();
  66 private:
  67
  68     //the thread we're executing the events in
  69     boost::thread * _thread;
  70
  71     //controlling the thread alive-state
  72     bool _running;
  73     bool _finished;
  74
  75     //main loop
  76     void run();
  77 };
  78
  79 } //namespage
  80
  81 #endif