GioCancellableconnect

Convenience function to connect to the GCancellable::cancelled signal. Also handles the race condition that may happen if the cancellable is cancelled right before connecting.

callback is called exactly once each time cancellable is cancelled, either directly at the time of the connect if cancellable is already cancelled, or when cancellable is cancelled in some thread. In case the cancellable is reset via g_cancellable_reset() then the callback can be called again if the cancellable is cancelled and if it had not been previously cancelled at the time g_cancellable_connect() was called (e.g. if the connection actually took place, returning a non-zero value).

data_destroy_func will be called when the handler is disconnected, or immediately if the cancellable is already cancelled.

See GCancellable::cancelled for details on how to use this.

Since GLib 2.40, the lock protecting cancellable is not held when callback is invoked. This lifts a restriction in place for earlier GLib versions which now makes it easier to write cleanup code that unconditionally invokes e.g. g_cancellable_cancel(). Note that since 2.82 GLib still holds a lock during the callback but it’s designed in a way that most of the GCancellable methods can be called, including g_cancellable_cancel() or g_object_unref().

There are still some methods that will deadlock (by design) when called from the GCancellable::cancelled callbacks: - g_cancellable_connect() - g_cancellable_disconnect() - g_cancellable_reset() - g_cancellable_make_pollfd() - g_cancellable_release_fd().

Available since: 2.22