From 10b6d0129d062f4d5d8a7611023c3f8cc43f1eab Mon Sep 17 00:00:00 2001
From: Zac Medico <zmedico@gentoo.org>
Date: Thu, 25 Oct 2012 01:35:31 -0700
Subject: Add FEATURES=merge-sync, for bug #439584.

---
 pym/portage/dbapi/vartree.py | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

(limited to 'pym/portage/dbapi')

diff --git a/pym/portage/dbapi/vartree.py b/pym/portage/dbapi/vartree.py
index cb7b39b02..edc477a09 100644
--- a/pym/portage/dbapi/vartree.py
+++ b/pym/portage/dbapi/vartree.py
@@ -30,6 +30,7 @@ portage.proxy.lazyimport.lazyimport(globals(),
 	'portage.util.env_update:env_update',
 	'portage.util.listdir:dircache,listdir',
 	'portage.util.movefile:movefile',
+	'portage.util._ctypes:find_library,LoadLibrary',
 	'portage.util._dyn_libs.PreservedLibsRegistry:PreservedLibsRegistry',
 	'portage.util._dyn_libs.LinkageMapELF:LinkageMapELF@LinkageMap',
 	'portage.util._async.SchedulerInterface:SchedulerInterface',
@@ -73,6 +74,7 @@ import io
 from itertools import chain
 import logging
 import os as _os
+import platform
 import pwd
 import re
 import stat
@@ -4688,7 +4690,44 @@ class dblink(object):
 		disk and avoid data-loss in the event of a power failure. This method
 		does nothing if FEATURES=merge-sync is disabled.
 		"""
-		pass
+		if not self._device_path_map or \
+			"merge-sync" not in self.settings.features:
+			return
+
+		syncfs = self._get_syncfs()
+		if syncfs is None:
+			try:
+				proc = subprocess.Popen(["sync"])
+			except EnvironmentError:
+				pass
+			else:
+				proc.wait()
+		else:
+			for path in self._device_path_map.values():
+				try:
+					fd = os.open(path, os.O_RDONLY)
+				except OSError:
+					pass
+				else:
+					try:
+						syncfs(fd)
+					except OSError:
+						pass
+					finally:
+						os.close(fd)
+
+	def _get_syncfs(self):
+		if platform.system() == "Linux":
+			filename = find_library("c")
+			if filename is not None:
+				library = LoadLibrary(filename)
+				if library is not None:
+					try:
+						return library.syncfs
+					except AttributeError:
+						pass
+
+		return None
 
 	def merge(self, mergeroot, inforoot, myroot=None, myebuild=None, cleanup=0,
 		mydbapi=None, prev_mtimes=None, counter=None):
-- 
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