/*
- Copyright (C) 2000-2007 Paul Davis
+ 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
#ifndef __pbd__crossthread_h__
#define __pbd__crossthread_h__
+#ifdef check
+#undef check
+#endif
+
#include <glibmm/main.h>
-class CrossThreadChannel {
- public:
- CrossThreadChannel();
+#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();
- int selectable() const { return fds[0]; }
+ /* 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 ();
- static void drain (int fd);
- /* glibmm 2.22 and earlier has a terrifying bug that will
- cause crashes whenever a Source is removed from
- a MainContext (including the destruction of the MainContext),
- because the Source is destroyed "out from under the nose of"
- the RefPtr. I (Paul) have fixed this (https://bugzilla.gnome.org/show_bug.cgi?id=561885)
- but in the meantime, we need a hack to get around the issue.
- */
+ 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();
- Glib::RefPtr<Glib::IOSource> ios();
- void drop_ios ();
+#ifndef PLATFORM_WINDOWS
+ int fds[2]; // current implementation uses a pipe/fifo
+#else
- bool ok() const { return fds[0] >= 0 && fds[1] >= 0; }
+ SOCKET send_socket;
+ SOCKET receive_socket;
+ struct sockaddr_in recv_address;
+#endif
- private:
- Glib::RefPtr<Glib::IOSource>* _ios; // lazily constructed
- int fds[2];
};
#endif /* __pbd__crossthread_h__ */