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/*
Copyright (C) 2000-2007 Paul Davis
This program 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 2 of the License, or
(at your option) any later version.
This program 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef __pbd__crossthread_h__
#define __pbd__crossthread_h__
#ifdef check
#undef check
#endif
#include <glibmm/main.h>
#include "pbd/libpbd_visibility.h"
#ifdef PLATFORM_WINDOWS
#include <windows.h>
#endif // PLATFORM_WINDOWS
/** A simple abstraction of a mechanism of signalling one thread from another.
* The signaller calls ::wakeup() to tell the signalled thread to check for
* work to be done.
*
* This implementation provides both ::selectable() for use in direct
* poll/select-based event loops, and a Glib::IOSource via ::ios() for use
* in Glib main loop based situations.
*/
class LIBPBD_API CrossThreadChannel {
public:
/** if @a non_blocking is true, the channel will not cause blocking
* when used in an event loop based on poll/select or the glib main
* loop.
*/
CrossThreadChannel(bool non_blocking);
~CrossThreadChannel();
/** Tell the listening thread that is has work to do.
*/
void wakeup();
/* if the listening thread cares about the precise message
* it is being sent, then ::deliver() can be used to send
* a single byte message rather than a simple wakeup. These
* two mechanisms should not be used on the same CrossThreadChannel
* because there is no way to know which byte value will be used
* for ::wakeup()
*/
int deliver (char msg);
/** if using ::deliver() to wakeup the listening thread, then
* the listener should call ::receive() to fetch the message
* type from the channel.
*
* wait = true only make sense for non_blocking channels,
* it polls for data to become available.
*/
int receive (char& msg, bool wait = false);
/** empty the channel of all requests.
* Typically this is done as soon as input
* is noticed on the channel, because the
* handler will look at a separately managed work
* queue. The actual number of queued "wakeups"
* in the channel will not be important.
*/
void drain ();
void set_receive_handler (sigc::slot<bool,Glib::IOCondition> s);
void attach (Glib::RefPtr<Glib::MainContext>);
private:
friend gboolean cross_thread_channel_call_receive_slot (GIOChannel*, GIOCondition condition, void *data);
GIOChannel* receive_channel;
GSource* receive_source;
sigc::slot<bool,Glib::IOCondition> receive_slot;
bool poll_for_request();
#ifndef PLATFORM_WINDOWS
int fds[2]; // current implementation uses a pipe/fifo
#else
SOCKET send_socket;
SOCKET receive_socket;
struct sockaddr_in recv_address;
#endif
};
#endif /* __pbd__crossthread_h__ */
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