Merge lp:~mvo/ubuntu-release-upgrader/lp1052605 into lp:ubuntu-release-upgrader

[Michael Vogt]

This branches fixes bug #1052605 by
a) spinning on the dpkg lock for a short while
b) reverting cleanly if the cache open fails after a sources.list update
   but before anything got installed

[lp:~mvo/ubuntu-release-upgrader/lp1052605]

2554. By Colin Watson on 2012-09-27

DistUpgrade/DistUpgradeController.py: Guard against UnboundLocalError in
doDistUpgradeFetching.

2555. By Brian Murray on 2012-09-27

ensure that apt-clone system state is included in bug reports filed by
apport

2556. By Brian Murray on 2012-09-27

DistUpgrade/DistUpgradeController.py: properly handle source entries with
unicode comments in them (LP: #1039484)

2557. By Brian Murray on 2012-09-27

releasing version 1:0.181

2558. By Brian Murray on 2012-09-28

Do not try to add apt-clone system state if it does not exist

2559. By Colin Watson on 2012-09-30

fix version number

2560. By Brian Murray on 2012-10-01

releasing version 1:0.182

2561. By Brian Murray on 2012-10-02

debian/ubuntu-release-upgrader-core.preinst: modify
/etc/dist-upgrader/release-upgrades to use Prompt instead of prompt
thereby avoiding a conffile prompt (LP: #1045579)

2562. By Brian Murray on 2012-10-02

releasing version 1:0.183

2563. By Colin Watson on 2012-10-02

Decode the output of apt_pkg.size_to_str() if necessary when
substituting it into Unicode strings (LP: #1031882).

2564. By Colin Watson on 2012-10-02

Ship /usr/share/keyrings/ubuntu-archive-keyring.gpg as
utils/apt/trusted.gpg (although that's only for tests anyway), rather
than whatever happens to be in /etc/apt/trusted.gpg on the system used
to build the source package.

2565. By Colin Watson on 2012-10-02

releasing version 1:0.184

[Michael Terry (mterry)]

Looks good to me

review: Approve

[lp:~mvo/ubuntu-release-upgrader/lp1052605]

2566. By Michael Vogt on 2012-10-02

* lp:~mvo/ubuntu-release-upgrader/lp1052605 into lp:ubuntu-release-upgrader:
   - spinning on the dpkg lock for a short while before giving up
   - reverting cleanly if the cache open fails after a sources.list update
     but before anything got installed
   (LP: #1052605)

=== modified file 'DistUpgrade/DistUpgradeController.py'
--- DistUpgrade/DistUpgradeController.py	2012-07-03 16:49:34 +0000
+++ DistUpgrade/DistUpgradeController.py	2012-09-21 12:38:36 +0000
@@ -191,13 +191,42 @@
         # apt cron job
         self._aptCronJobPerms = 0o755
 
-    def openCache(self, lock=True):
+    def openCache(self, lock=True, restore_sources_list_on_fail=False):
         logging.debug("openCache()")
         if self.cache is None:
             self.quirks.run("PreCacheOpen")
         else:
             self.cache.release_lock()
             self.cache.unlock_lists_dir()
+        # this loop will try getting the lock a couple of times
+        MAX_LOCK_RETRIES = 20
+        lock_retry = 0
+        while True:
+            try:
+                # exit here once the cache is ready
+                return self._openCache(lock)
+            except CacheExceptionLockingFailed as e:
+                # wait a bit
+                lock_retry += 1
+                self._view.processEvents()
+                time.sleep(0.1)
+                logging.debug(
+                    "failed to lock the cache, retrying (%i)" % lock_retry)
+                # and give up after some time
+                if lock_retry > MAX_LOCK_RETRIES:
+                    logging.error("Cache can not be locked (%s)" % e)
+                    self._view.error(_("Unable to get exclusive lock"),
+                                     _("This usually means that another "
+                                       "package management application "
+                                       "(like apt-get or aptitude) "
+                                       "already running. Please close that "
+                                       "application first."));
+                    if restore_sources_list_on_fail:
+                        self.abort()
+                    else:
+                        sys.exit(1)
+
+    def _openCache(self, lock):
         try:
             self.cache = MyCache(self.config,
                                  self._view,
@@ -218,15 +247,6 @@
                                  self._view,
                                  self.quirks,
                                  self._view.getOpCacheProgress())
-        except CacheExceptionLockingFailed as e:
-            logging.error("Cache can not be locked (%s)" % e)
-            self._view.error(_("Unable to get exclusive lock"),
-                             _("This usually means that another "
-                               "package management application "
-                               "(like apt-get or aptitude) "
-                               "already running. Please close that "
-                               "application first."));
-            sys.exit(1)
         self.cache.partialUpgrade = self._partialUpgrade
         logging.debug("/openCache(), new cache size %i" % len(self.cache))
 
@@ -1651,7 +1671,10 @@
 
         # then open the cache (again)
         self._view.updateStatus(_("Checking package manager"))
-        self.openCache()
+        # if something fails here (e.g. locking the cache) we need to
+        # restore the system state (LP: #1052605)
+        self.openCache(restore_sources_list_on_fail=True)
+
         # re-check server mode because we got new packages (it may happen
         # that the system had no sources.list entries and therefore no
         # desktop file information)