PollScheduler: tweek termination logic

* PollScheduler and all subclasses now use the _terminated_tasks
  variable to check whether or not _terminate_tasks() has been called,
  and behave appropriately in that case.

* The _schedule_tasks() method now has documentation about the
  relationship with _terminate_tasks() and _terminated_tasks.

4 files changed, 36 insertions, 11 deletions

diff --git a/pym/_emerge/MetadataRegen.py b/pym/_emerge/MetadataRegen.py
index 45c4f4d29..810317533 100644
--- a/pym/_emerge/MetadataRegen.py
+++ b/pym/_emerge/MetadataRegen.py
@@ -44,7 +44,7 @@ class MetadataRegen(PollScheduler):
 		portage.writemsg_stdout("Regenerating cache entries...\n")
 		every_cp.sort(reverse=True)
 		try:
-			while not self._terminated.is_set():
+			while not self._terminated_tasks:
 				yield every_cp.pop()
 		except IndexError:
 			pass
@@ -56,13 +56,13 @@ class MetadataRegen(PollScheduler):
 		consumer = self._consumer
 
 		for cp in self._cp_iter:
-			if self._terminated.is_set():
+			if self._terminated_tasks:
 				break
 			cp_set.add(cp)
 			portage.writemsg_stdout("Processing %s\n" % cp)
 			cpv_list = portdb.cp_list(cp)
 			for cpv in cpv_list:
-				if self._terminated.is_set():
+				if self._terminated_tasks:
 					break
 				valid_pkgs.add(cpv)
 				ebuild_path, repo_path = portdb.findname2(cpv)
@@ -94,7 +94,7 @@ class MetadataRegen(PollScheduler):
 		while self._jobs:
 			self._poll_loop()
 
-		if self._terminated.is_set():
+		if self._terminated_tasks:
 			self.returncode = 1
 			return
 
@@ -145,9 +145,10 @@ class MetadataRegen(PollScheduler):
 		@returns: True if there may be remaining tasks to schedule,
 			False otherwise.
 		"""
+		if self._terminated_tasks:
+			return False
+
 		while self._can_add_job():
-			if self._terminated.is_set():
-				return False
 			try:
 				metadata_process = next(self._process_iter)
 			except StopIteration:
@@ -167,7 +168,7 @@ class MetadataRegen(PollScheduler):
 			self.returncode = 1
 			self._error_count += 1
 			self._valid_pkgs.discard(metadata_process.cpv)
-			if not self._terminated.is_set():
+			if not self._terminated_tasks:
 				portage.writemsg("Error processing %s, continuing...\n" % \
 					(metadata_process.cpv,), noiselevel=-1)
 
diff --git a/pym/_emerge/PollScheduler.py b/pym/_emerge/PollScheduler.py
index 94fd92407..8f4bd64b9 100644
--- a/pym/_emerge/PollScheduler.py
+++ b/pym/_emerge/PollScheduler.py
@@ -65,6 +65,24 @@ class PollScheduler(object):
 		"""
 		raise NotImplementedError()
 
+	def _schedule_tasks(self):
+		"""
+		This is called from inside the _schedule() method, which
+		guarantees the following:
+
+		1) It will not be called recursively.
+		2) _terminate_tasks() will not be called while it is running.
+		3) The state of the boolean _terminated_tasks variable will
+		   not change while it is running.
+
+		Unless this method is used to perform user interface updates,
+		or something like that, the first thing it should do is check
+		the state of _terminated_tasks and if that is True then it
+		should return False immediately (since there's no need to
+		schedule anything after _terminate_tasks() has been called).
+		"""
+		raise NotImplementedError()
+
 	def _schedule(self):
 		"""
 		Calls _schedule_tasks() and automatically returns early from
@@ -90,6 +108,9 @@ class PollScheduler(object):
 		return self._jobs
 
 	def _can_add_job(self):
+		if self._terminated_tasks:
+			return False
+
 		max_jobs = self._max_jobs
 		max_load = self._max_load
 
diff --git a/pym/_emerge/QueueScheduler.py b/pym/_emerge/QueueScheduler.py
index 8a7ea300a..2d727c95d 100644
--- a/pym/_emerge/QueueScheduler.py
+++ b/pym/_emerge/QueueScheduler.py
@@ -79,6 +79,9 @@ class QueueScheduler(PollScheduler):
 		@returns: True if there may be remaining tasks to schedule,
 			False otherwise.
 		"""
+		if self._terminated_tasks:
+			return False
+
 		while self._can_add_job():
 			n = self._max_jobs - self._running_job_count()
 			if n < 1:
diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index 306c945d7..2f49c3420 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -1441,7 +1441,7 @@ class Scheduler(PollScheduler):
 				build_dir=build_dir, build_log=build_log,
 				pkg=pkg,
 				returncode=merge.returncode))
-			if not self._terminated.is_set():
+			if not self._terminated_tasks:
 				self._failed_pkg_msg(self._failed_pkgs[-1], "install", "to")
 				self._status_display.failed = len(self._failed_pkgs)
 			return
@@ -1476,7 +1476,7 @@ class Scheduler(PollScheduler):
 		mtimedb.commit()
 
 	def _build_exit(self, build):
-		if build.returncode == os.EX_OK and self._terminated.is_set():
+		if build.returncode == os.EX_OK and self._terminated_tasks:
 			# We've been interrupted, so we won't
 			# add this to the merge queue.
 			self.curval += 1
@@ -1505,7 +1505,7 @@ class Scheduler(PollScheduler):
 				build_dir=build_dir, build_log=build_log,
 				pkg=build.pkg,
 				returncode=build.returncode))
-			if not self._terminated.is_set():
+			if not self._terminated_tasks:
 				self._failed_pkg_msg(self._failed_pkgs[-1], "emerge", "for")
 				self._status_display.failed = len(self._failed_pkgs)
 			self._deallocate_config(build.settings)
@@ -1685,7 +1685,7 @@ class Scheduler(PollScheduler):
 				self._poll_loop()
 
 	def _keep_scheduling(self):
-		return bool(not self._terminated.is_set() and self._pkg_queue and \
+		return bool(not self._terminated_tasks and self._pkg_queue and \
 			not (self._failed_pkgs and not self._build_opts.fetchonly))
 
 	def _is_work_scheduled(self):