* Optimize SequentialTaskQueue.schedule() by using a _dirty attribute

  to track whether anything relevant has changed since the last schedule
  call. Since we can always rely on exist listeners being called, set of
  running tasks is always pruned automatically and there is never any need
  to actively prune it.
* Remove the unused SequentialTaskQueue.auto_schedule feature.

svn path=/main/trunk/; revision=11275

1 files changed, 18 insertions, 13 deletions

diff --git a/pym/_emerge/__init__.py b/pym/_emerge/__init__.py
index 09ce0b7c5..074ecc68e 100644
--- a/pym/_emerge/__init__.py
+++ b/pym/_emerge/__init__.py
@@ -8112,8 +8112,8 @@ class PollSelectAdapter(PollConstants):
 
 class SequentialTaskQueue(SlotObject):
 
-	__slots__ = ("auto_schedule", "max_jobs", "running_tasks") + \
-		("_task_queue", "_scheduling")
+	__slots__ = ("max_jobs", "running_tasks") + \
+		("_dirty", "_scheduling", "_task_queue")
 
 	def __init__(self, **kwargs):
 		SlotObject.__init__(self, **kwargs)
@@ -8121,19 +8121,21 @@ class SequentialTaskQueue(SlotObject):
 		self.running_tasks = set()
 		if self.max_jobs is None:
 			self.max_jobs = 1
+		self._dirty = True
 
 	def add(self, task):
 		self._task_queue.append(task)
-		if self.auto_schedule:
-			self.schedule()
+		self._dirty = True
 
 	def addFront(self, task):
 		self._task_queue.appendleft(task)
-		if self.auto_schedule:
-			self.schedule()
+		self._dirty = True
 
 	def schedule(self):
 
+		if not self._dirty:
+			return False
+
 		if not self:
 			return False
 
@@ -8149,10 +8151,6 @@ class SequentialTaskQueue(SlotObject):
 		max_jobs = self.max_jobs
 		state_changed = False
 
-		for task in list(running_tasks):
-			if task.poll() is not None:
-				state_changed = True
-
 		while task_queue and \
 			(max_jobs is True or len(running_tasks) < max_jobs):
 			task = task_queue.popleft()
@@ -8163,14 +8161,20 @@ class SequentialTaskQueue(SlotObject):
 				task.start()
 			state_changed = True
 
+		self._dirty = False
 		self._scheduling = False
 
 		return state_changed
 
 	def _task_exit(self, task):
-		self.running_tasks.discard(task)
-		if self.auto_schedule:
-			self.schedule()
+		"""
+		Since we can always rely on exist listeners being called, set of
+ 		running tasks is always pruned automatically and there is never any need
+		to actively prune it.
+		"""
+		self.running_tasks.remove(task)
+		if self._task_queue:
+			self._dirty = True
 
 	def clear(self):
 		self._task_queue.clear()
@@ -8179,6 +8183,7 @@ class SequentialTaskQueue(SlotObject):
 			task = running_tasks.pop()
 			task.removeExitListener(self._task_exit)
 			task.cancel()
+		self._dirty = False
 
 	def __nonzero__(self):
 		return bool(self._task_queue or self.running_tasks)