Add run_main_scheduler helper function.

1 files changed, 41 insertions, 0 deletions

diff --git a/pym/portage/util/_async/run_main_scheduler.py b/pym/portage/util/_async/run_main_scheduler.py
new file mode 100644
index 000000000..10fed34b3
--- /dev/null
+++ b/pym/portage/util/_async/run_main_scheduler.py
@@ -0,0 +1,41 @@
+
+import signal
+
+def run_main_scheduler(scheduler):
+	"""
+	Start and run an AsyncScheduler (or compatible object), and handle
+	SIGINT or SIGTERM by calling its terminate() method and waiting
+	for it to clean up after itself. If SIGINT or SIGTERM is received,
+	return signum, else return None. Any previous SIGINT or SIGTERM
+	signal handlers are automatically saved and restored before
+	returning.
+	"""
+
+	received_signal = []
+
+	def sighandler(signum, frame):
+		signal.signal(signal.SIGINT, signal.SIG_IGN)
+		signal.signal(signal.SIGTERM, signal.SIG_IGN)
+		received_signal.append(signum)
+		scheduler.terminate()
+
+	earlier_sigint_handler = signal.signal(signal.SIGINT, sighandler)
+	earlier_sigterm_handler = signal.signal(signal.SIGTERM, sighandler)
+
+	try:
+		scheduler.start()
+		scheduler.wait()
+	finally:
+		# Restore previous handlers
+		if earlier_sigint_handler is not None:
+			signal.signal(signal.SIGINT, earlier_sigint_handler)
+		else:
+			signal.signal(signal.SIGINT, signal.SIG_DFL)
+		if earlier_sigterm_handler is not None:
+			signal.signal(signal.SIGTERM, earlier_sigterm_handler)
+		else:
+			signal.signal(signal.SIGTERM, signal.SIG_DFL)
+
+	if received_signal:
+		return received_signal[0]
+	return None