libs/pbd/pbd/signals.h

   1 /*
   2     Copyright (C) 2009-2012 Paul Davis
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 */
  19
  20 #ifndef __pbd_signals_h__
  21 #define __pbd_signals_h__
  22
  23 #include <csignal>
  24
  25 #include <list>
  26 #include <map>
  27
  28 #ifdef nil
  29 #undef nil
  30 #endif
  31
  32 #include <glibmm/threads.h>
  33
  34 #include <boost/noncopyable.hpp>
  35 #include <boost/bind.hpp>
  36 #include <boost/bind/protect.hpp>
  37 #include <boost/function.hpp>
  38 #include <boost/enable_shared_from_this.hpp>
  39 #include <boost/optional.hpp>
  40
  41 #include "pbd/libpbd_visibility.h"
  42 #include "pbd/event_loop.h"
  43
  44 #ifndef NDEBUG
  45 #define DEBUG_PBD_SIGNAL_CONNECTIONS
  46 #endif
  47
  48 #ifdef DEBUG_PBD_SIGNAL_CONNECTIONS
  49 #include "pbd/stacktrace.h"
  50 #include <iostream>
  51 #endif
  52
  53 namespace PBD {
  54
  55 class LIBPBD_API Connection;
  56
  57 class LIBPBD_API SignalBase
  58 {
  59 public:
  60         SignalBase ()
  61 #ifdef DEBUG_PBD_SIGNAL_CONNECTIONS
  62         : _debug_connection (false)
  63 #endif
  64         {}
  65         virtual ~SignalBase () {}
  66         virtual void disconnect (boost::shared_ptr<Connection>) = 0;
  67 #ifdef DEBUG_PBD_SIGNAL_CONNECTIONS
  68         void set_debug_connection (bool yn) { _debug_connection = yn; }
  69 #endif
  70
  71 protected:
  72         mutable Glib::Threads::Mutex _mutex;
  73 #ifdef DEBUG_PBD_SIGNAL_CONNECTIONS
  74         bool _debug_connection;
  75 #endif
  76 };
  77
  78 class LIBPBD_API Connection : public boost::enable_shared_from_this<Connection>
  79 {
  80 public:
  81         Connection (SignalBase* b, PBD::EventLoop::InvalidationRecord* ir) : _signal (b), _invalidation_record (ir)
  82         {
  83                 if (_invalidation_record) {
  84                         _invalidation_record->ref ();
  85                 }
  86         }
  87
  88         void disconnect ()
  89         {
  90                 Glib::Threads::Mutex::Lock lm (_mutex);
  91                 if (_signal) {
  92                         _signal->disconnect (shared_from_this ());
  93                         _signal = 0;
  94                 }
  95         }
  96
  97         void disconnected ()
  98         {
  99                 if (_invalidation_record) {
 100                         _invalidation_record->unref ();
 101                 }
 102         }
 103
 104         void signal_going_away ()
 105         {
 106                 Glib::Threads::Mutex::Lock lm (_mutex);
 107                 if (_invalidation_record) {
 108                         _invalidation_record->unref ();
 109                 }
 110                 _signal = 0;
 111         }
 112
 113 private:
 114         Glib::Threads::Mutex _mutex;
 115         SignalBase* _signal;
 116         PBD::EventLoop::InvalidationRecord* _invalidation_record;
 117 };
 118
 119 template<typename R>
 120 class /*LIBPBD_API*/ OptionalLastValue
 121 {
 122 public:
 123         typedef boost::optional<R> result_type;
 124
 125         template <typename Iter>
 126         result_type operator() (Iter first, Iter last) const {
 127                 result_type r;
 128                 while (first != last) {
 129                         r = *first;
 130                         ++first;
 131                 }
 132
 133                 return r;
 134         }
 135 };
 136
 137 typedef boost::shared_ptr<Connection> UnscopedConnection;
 138
 139 class LIBPBD_API ScopedConnection
 140 {
 141 public:
 142         ScopedConnection () {}
 143         ScopedConnection (UnscopedConnection c) : _c (c) {}
 144         ~ScopedConnection () {
 145                 disconnect ();
 146         }
 147
 148         void disconnect ()
 149         {
 150                 if (_c) {
 151                         _c->disconnect ();
 152                 }
 153         }
 154
 155         ScopedConnection& operator= (UnscopedConnection const & o)
 156         {
 157                 if (_c == o) {
 158                         return *this;
 159                 }
 160
 161                 disconnect ();
 162                 _c = o;
 163                 return *this;
 164         }
 165
 166 private:
 167         UnscopedConnection _c;
 168 };
 169
 170 class LIBPBD_API ScopedConnectionList  : public boost::noncopyable
 171 {
 172   public:
 173         ScopedConnectionList();
 174         virtual ~ScopedConnectionList ();
 175
 176         void add_connection (const UnscopedConnection& c);
 177         void drop_connections ();
 178
 179   private:
 180         /* this class is not copyable */
 181         ScopedConnectionList(const ScopedConnectionList&);
 182
 183         /* Even though our signals code is thread-safe, this additional list of
 184            scoped connections needs to be protected in 2 cases:
 185
 186            (1) (unlikely) we make a connection involving a callback on the
 187                same object from 2 threads. (wouldn't that just be appalling
 188                programming style?)
 189
 190            (2) where we are dropping connections in one thread and adding
 191                one from another.
 192          */
 193
 194         Glib::Threads::Mutex _scoped_connection_lock;
 195
 196         typedef std::list<ScopedConnection*> ConnectionList;
 197         ConnectionList _scoped_connection_list;
 198 };
 199
 200 #include "pbd/signals_generated.h"
 201
 202 } /* namespace */
 203
 204 #endif /* __pbd_signals_h__ */