PollScheduler: use timeout for loadavg checks

This ensures that the code from commit
fe03b5fd790fc09bd6594c55bb174e80aaac1e5a behaves correctly even when
there are no poll events arriving for a long time (which might happen
if the running builds don't produce output for a long time).

1 files changed, 12 insertions, 6 deletions

diff --git a/pym/_emerge/PollScheduler.py b/pym/_emerge/PollScheduler.py
index 5103e31d6..808fa6e1f 100644
--- a/pym/_emerge/PollScheduler.py
+++ b/pym/_emerge/PollScheduler.py
@@ -20,6 +20,9 @@ from _emerge.getloadavg import getloadavg
 
 class PollScheduler(object):
 
+	# max time between loadavg checks (milliseconds)
+	_loadavg_latency = 30000
+
 	class _sched_iface_class(SlotObject):
 		__slots__ = ("IO_ERR", "IO_HUP", "IO_IN", "IO_NVAL", "IO_OUT",
 			"IO_PRI", "child_watch_add",
@@ -147,23 +150,24 @@ class PollScheduler(object):
 
 	def _main_loop(self):
 		term_check_id = self.sched_iface.idle_add(self._termination_check)
+		loadavg_check_id = None
+		if self._max_load is not None:
+			# We have to schedule periodically, in case the load
+			# average has changed since the last call.
+			loadavg_check_id = self.sched_iface.timeout_add(
+				self._loadavg_latency, self._schedule)
+
 		try:
 			# Populate initial event sources. Unless we're scheduling
 			# based on load average, we only need to do this once
 			# here, since it can be called during the loop from within
 			# event handlers.
 			self._schedule()
-			max_load = self._max_load
 
 			# Loop while there are jobs to be scheduled.
 			while self._keep_scheduling():
 				self.sched_iface.iteration()
 
-				if max_load is not None:
-					# We have to schedule periodically, in case the load
-					# average has changed since the last call.
-					self._schedule()
-
 			# Clean shutdown of previously scheduled jobs. In the
 			# case of termination, this allows for basic cleanup
 			# such as flushing of buffered output to logs.
@@ -171,6 +175,8 @@ class PollScheduler(object):
 				self.sched_iface.iteration()
 		finally:
 			self.sched_iface.source_remove(term_check_id)
+			if loadavg_check_id is not None:
+				self.sched_iface.source_remove(loadavg_check_id)
 
 	def _is_work_scheduled(self):
 		return bool(self._running_job_count())