Merge lp:~alan-griffiths/mir/avoid-possible-error into lp:mir

[Alan Griffiths]

examples: keep titlebar around until it can't be needed.

examples: keep titlebar around until it can't be needed.

Andreas spotted this exception: http://paste.ubuntu.com/12713256/

Which seems to occur because the last surface in the only session is being deleted, the titlebar is first forgotten, then an attempt made to focus on the "next" session which leads to the *same* surface being made active. That leads to an attempt to repaint the titlebar using "info" about the titlebar that was forgotten earlier. Boom!

[Alan Griffiths (alan-griffiths)]

What I don't see is why I can't reproduce.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:3006
http://jenkins.qa.ubuntu.com/job/mir-ci/5207/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-android-vivid-i386-build/4362
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-clang-vivid-amd64-build/3269
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-vivid-touch/4304
    FAILURE: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-wily-touch/262/console
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-wily-amd64-ci/1361
        deb: http://jenkins.qa.ubuntu.com/job/mir-wily-amd64-ci/1361/artifact/work/output/*zip*/output.zip
    FAILURE: http://jenkins.qa.ubuntu.com/job/mir-wily-i386-ci/262/console
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-builder-vivid-armhf/4305
        deb: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-builder-vivid-armhf/4305/artifact/work/output/*zip*/output.zip
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-runner-touch/6960
    SUCCESS: http://s-jenkins.ubuntu-ci:8080/job/touch-flash-device/24063
    FAILURE: http://jenkins.qa.ubuntu.com/job/mir-mediumtests-builder-wily-armhf/263/console

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/mir-ci/5207/rebuild

review: Approve (continuous-integration)

[Andreas Pokorny (andreas-pokorny)]

this fixes the exceptions being thrown around during shutdown..
and I am no longer able to reproduce the seg fault that

review: Approve

[Andreas Pokorny (andreas-pokorny)]

.. that plagued the krillins on ci recently.

=== modified file 'examples/server_example_canonical_window_manager.cpp'
--- examples/server_example_canonical_window_manager.cpp	2015-10-02 01:56:04 +0000
+++ examples/server_example_canonical_window_manager.cpp	2015-10-08 10:35:11 +0000
@@ -595,18 +595,18 @@
         }
     }
 
+    if (!--tools->info_for(session).surfaces && session == tools->focused_session())
+    {
+        active_surface_.reset();
+        tools->focus_next_session();
+        select_active_surface(tools->focused_surface());
+    }
+
     if (info.titlebar)
     {
         tools->forget(info.titlebar);
         session->destroy_surface(info.titlebar_id);
     }
-
-    if (!--tools->info_for(session).surfaces && session == tools->focused_session())
-    {
-        active_surface_.reset();
-        tools->focus_next_session();
-        select_active_surface(tools->focused_surface());
-    }
 }
 
 int me::CanonicalWindowManagerPolicyCopy::handle_set_state(std::shared_ptr<ms::Surface> const& surface, MirSurfaceState value)