From 56337b00ea46d96037037816d7b5c7904825b8a9 Mon Sep 17 00:00:00 2001
From: Zac Medico <zmedico@gentoo.org>
Date: Thu, 9 Feb 2012 12:04:42 -0800
Subject: [PATCH] Add global_event_loop() and GlibEventLoop.

This causes all PollScheduler instances within a given process to share
a singleton EventLoop instance, and also makes it possible to swap in
glib's main loop for all portage event loops in the main process.
---
 pym/_emerge/PollScheduler.py                  |  4 +--
 pym/portage/util/_eventloop/EventLoop.py      |  2 ++
 pym/portage/util/_eventloop/GlibEventLoop.py  | 20 +++++++++++
 .../util/_eventloop/global_event_loop.py      | 36 +++++++++++++++++++
 4 files changed, 60 insertions(+), 2 deletions(-)
 create mode 100644 pym/portage/util/_eventloop/GlibEventLoop.py
 create mode 100644 pym/portage/util/_eventloop/global_event_loop.py

diff --git a/pym/_emerge/PollScheduler.py b/pym/_emerge/PollScheduler.py
index 165c618d1..3b86fa08e 100644
--- a/pym/_emerge/PollScheduler.py
+++ b/pym/_emerge/PollScheduler.py
@@ -12,7 +12,7 @@ except ImportError:
 from portage import _encodings
 from portage import _unicode_encode
 from portage.util import writemsg_level
-from portage.util._eventloop.EventLoop import EventLoop
+from portage.util._eventloop.global_event_loop import global_event_loop
 
 from _emerge.SlotObject import SlotObject
 from _emerge.getloadavg import getloadavg
@@ -32,7 +32,7 @@ class PollScheduler(object):
 		self._jobs = 0
 		self._scheduling = False
 		self._background = False
-		self._event_loop = EventLoop()
+		self._event_loop = global_event_loop()
 		self.sched_iface = self._sched_iface_class(
 			idle_add=self._event_loop.idle_add,
 			io_add_watch=self._event_loop.io_add_watch,
diff --git a/pym/portage/util/_eventloop/EventLoop.py b/pym/portage/util/_eventloop/EventLoop.py
index 3f4d35445..aa78ccd15 100644
--- a/pym/portage/util/_eventloop/EventLoop.py
+++ b/pym/portage/util/_eventloop/EventLoop.py
@@ -13,6 +13,8 @@ from _emerge.PollSelectAdapter import PollSelectAdapter
 
 class EventLoop(object):
 
+	supports_multiprocessing = True
+
 	class _idle_callback_class(SlotObject):
 		__slots__ = ("args", "callback", "source_id")
 
diff --git a/pym/portage/util/_eventloop/GlibEventLoop.py b/pym/portage/util/_eventloop/GlibEventLoop.py
new file mode 100644
index 000000000..b35772e7f
--- /dev/null
+++ b/pym/portage/util/_eventloop/GlibEventLoop.py
@@ -0,0 +1,20 @@
+# Copyright 2012 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+import portage
+portage.proxy.lazyimport.lazyimport(globals(),
+	'glib',
+)
+
+class GlibEventLoop(object):
+
+	# TODO: Support multiprocessing by using a separate glib.MainContext
+	# instance for each process.
+	supports_multiprocessing = False
+
+	def __init__(self):
+		self.iteration = glib.main_context_default().iteration
+		self.idle_add = glib.idle_add
+		self.io_add_watch = glib.io_add_watch
+		self.timeout_add = glib.timeout_add
+		self.source_remove = glib.source_remove
diff --git a/pym/portage/util/_eventloop/global_event_loop.py b/pym/portage/util/_eventloop/global_event_loop.py
new file mode 100644
index 000000000..0f0c53f2b
--- /dev/null
+++ b/pym/portage/util/_eventloop/global_event_loop.py
@@ -0,0 +1,36 @@
+# Copyright 2012 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+import os
+
+from portage.util._eventloop.EventLoop import EventLoop
+
+_default_constructor = EventLoop
+#from portage.util._eventloop.GlibEventLoop \
+#	import GlibEventLoop as _default_constructor
+
+# If _default_constructor doesn't support multiprocessing,
+# then _multiprocessing_constructor is used in subprocesses.
+_multiprocessing_constructor = EventLoop
+
+_MAIN_PID = os.getpid()
+_instances = {}
+
+def global_event_loop():
+	"""
+	Get a global EventLoop (or compatible object) instance which
+	belongs exclusively to the current process.
+	"""
+
+	pid = os.getpid()
+	instance = _instances.get(pid)
+	if instance is not None:
+		return instance
+
+	constructor = _default_constructor
+	if not constructor.supports_multiprocessing and pid != _MAIN_PID:
+		constructor = _multiprocessing_constructor
+
+	instance = constructor()
+	_instances[pid] = instance
+	return instance
-- 
2.26.2