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// SPDX-License-Identifier: GPL-2.0-or-later
#ifndef INKSCAPE_UI_WIDGET_CANVAS_SYNCHRONIZER_H
#define INKSCAPE_UI_WIDGET_CANVAS_SYNCHRONIZER_H
#include <functional>
#include <vector>
#include <mutex>
#include <condition_variable>
#include <sigc++/sigc++.h>
#include <glibmm/dispatcher.h>
namespace Inkscape::UI::Widget {
// Synchronisation primitive suiting the canvas's needs. All synchronisation between the main/render threads goes through here.
class Synchronizer
{
public:
Synchronizer();
// Background side:
// Indicate that the background process has exited, causing EITHER signal_exit to be emitted OR waitforexit() to unblock.
void signalExit() const;
// Block until the given function has executed in the main thread, possibly waking it up if it is itself blocked.
// (Note: This is necessary for servicing occasional buffer mapping requests where one can't be pulled from a pool.)
void runInMain(std::function<void()> const &f) const;
// Main-thread side:
// Block until the background process has exited, gobbling the emission of signal_exit in the process.
void waitForExit() const;
// Connect to signal_exit.
sigc::connection connectExit(sigc::slot<void()> const &slot);
private:
struct Slot
{
std::function<void()> const *func;
};
Glib::Dispatcher dispatcher; // Used to wake up main thread if idle in GTK main loop.
sigc::signal<void()> signal_exit;
mutable std::mutex mutables;
mutable bool exitposted = false;
mutable bool main_blocked = false; // Whether main thread is blocked in waitForExit().
mutable std::condition_variable main_cond; // Used to wake up main thread if blocked.
mutable std::vector<Slot*> slots; // List of functions from runInMain() waiting to be run.
mutable std::condition_variable slots_cond; // Used to wake up render threads blocked in runInMain().
void awaken() const;
void on_dispatcher() const;
void process_slots(std::unique_lock<std::mutex> &lock) const;
};
} // namespace Inkscape::UI::Widget
#endif // INKSCAPE_UI_WIDGET_CANVAS_SYNCHRONIZER_H
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
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