Add run_main_scheduler helper function.

diff --git a/pym/portage/util/_async/run_main_scheduler.py b/pym/portage/util/_async/run_main_scheduler.py
new file mode 100644 (file)
index 0000000..10fed34
--- /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