109 lines
3.2 KiB
C++
109 lines
3.2 KiB
C++
/*
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Copyright (C) 2000-2007 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __pbd__crossthread_h__
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#define __pbd__crossthread_h__
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#ifdef check
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#undef check
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#endif
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#include <glibmm/main.h>
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#include "pbd/libpbd_visibility.h"
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#ifdef PLATFORM_WINDOWS
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#include <windows.h>
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#endif // PLATFORM_WINDOWS
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/** A simple abstraction of a mechanism of signalling one thread from another.
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* The signaller calls ::wakeup() to tell the signalled thread to check for
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* work to be done.
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*
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* This implementation provides both ::selectable() for use in direct
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* poll/select-based event loops, and a Glib::IOSource via ::ios() for use
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* in Glib main loop based situations.
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*/
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class LIBPBD_API CrossThreadChannel {
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public:
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/** if @a non_blocking is true, the channel will not cause blocking
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* when used in an event loop based on poll/select or the glib main
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* loop.
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*/
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CrossThreadChannel(bool non_blocking);
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~CrossThreadChannel();
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/** Tell the listening thread that is has work to do.
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*/
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void wakeup();
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/* if the listening thread cares about the precise message
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* it is being sent, then ::deliver() can be used to send
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* a single byte message rather than a simple wakeup. These
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* two mechanisms should not be used on the same CrossThreadChannel
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* because there is no way to know which byte value will be used
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* for ::wakeup()
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*/
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int deliver (char msg);
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/** if using ::deliver() to wakeup the listening thread, then
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* the listener should call ::receive() to fetch the message
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* type from the channel.
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*
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* wait = true only make sense for non_blocking channels,
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* it polls for data to become available.
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*/
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int receive (char& msg, bool wait = false);
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/** empty the channel of all requests.
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* Typically this is done as soon as input
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* is noticed on the channel, because the
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* handler will look at a separately managed work
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* queue. The actual number of queued "wakeups"
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* in the channel will not be important.
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*/
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void drain ();
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void set_receive_handler (sigc::slot<bool,Glib::IOCondition> s);
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void attach (Glib::RefPtr<Glib::MainContext>);
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private:
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friend gboolean cross_thread_channel_call_receive_slot (GIOChannel*, GIOCondition condition, void *data);
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GIOChannel* receive_channel;
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GSource* receive_source;
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sigc::slot<bool,Glib::IOCondition> receive_slot;
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bool poll_for_request();
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#ifndef PLATFORM_WINDOWS
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int fds[2]; // current implementation uses a pipe/fifo
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#else
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SOCKET send_socket;
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SOCKET receive_socket;
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struct sockaddr_in recv_address;
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#endif
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};
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#endif /* __pbd__crossthread_h__ */
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