2 Copyright (C) 2000-2007 Paul Davis
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.
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.
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.
20 #ifndef __pbd__crossthread_h__
21 #define __pbd__crossthread_h__
27 #include <glibmm/main.h>
29 #include "pbd/libpbd_visibility.h"
31 #ifdef PLATFORM_WINDOWS
33 #endif // PLATFORM_WINDOWS
36 /** A simple abstraction of a mechanism of signalling one thread from another.
37 * The signaller calls ::wakeup() to tell the signalled thread to check for
40 * This implementation provides both ::selectable() for use in direct
41 * poll/select-based event loops, and a Glib::IOSource via ::ios() for use
42 * in Glib main loop based situations.
45 class LIBPBD_API CrossThreadChannel {
47 /** if @a non_blocking is true, the channel will not cause blocking
48 * when used in an event loop based on poll/select or the glib main
51 CrossThreadChannel(bool non_blocking);
52 ~CrossThreadChannel();
54 /** Tell the listening thread that is has work to do.
58 /* if the listening thread cares about the precise message
59 * it is being sent, then ::deliver() can be used to send
60 * a single byte message rather than a simple wakeup. These
61 * two mechanisms should not be used on the same CrossThreadChannel
62 * because there is no way to know which byte value will be used
65 int deliver (char msg);
67 /** if using ::deliver() to wakeup the listening thread, then
68 * the listener should call ::receive() to fetch the message
69 * type from the channel.
71 * wait = true only make sense for non_blocking channels,
72 * it polls for data to become available.
74 int receive (char& msg, bool wait = false);
76 /** empty the channel of all requests.
77 * Typically this is done as soon as input
78 * is noticed on the channel, because the
79 * handler will look at a separately managed work
80 * queue. The actual number of queued "wakeups"
81 * in the channel will not be important.
85 void set_receive_handler (sigc::slot<bool,Glib::IOCondition> s);
86 void attach (Glib::RefPtr<Glib::MainContext>);
89 friend gboolean cross_thread_channel_call_receive_slot (GIOChannel*, GIOCondition condition, void *data);
91 GIOChannel* receive_channel;
92 GSource* receive_source;
93 sigc::slot<bool,Glib::IOCondition> receive_slot;
95 bool poll_for_request();
97 #ifndef PLATFORM_WINDOWS
98 int fds[2]; // current implementation uses a pipe/fifo
102 SOCKET receive_socket;
103 struct sockaddr_in recv_address;
108 #endif /* __pbd__crossthread_h__ */