Merge lp:~alan-griffiths/compiz-core/Workaround-unityshell-SIGSEGV into lp:compiz-core/0.9.8

[Alan Griffiths]

Workaround for some SIGSEGV crashes when unityshell is finalized & initialized.

It doesn't fix everything and doesn't fix the underlying problem, but does reduce frequency of crashes.

[Alan Griffiths (alan-griffiths)]

It isn't clear why this makes a difference.

The unityshell library isn't actually unloaded by it (and adding the missing dlclose to {unity}/plugins/unityshell/src/unityshell.cpp doesn't help).

[Daniel van Vugt (vanvugt)]

I would prefer that we keep crashing so that Unity gets fixed, rather than hiding the crashes indefinitely. It's not impossible to fix them; I remember in 11.04 (and 11.10?) we managed to fix most of the Unity crashes that were triggered from plugin reloads. So fixing the new crashes in Unity 5 shouldn't be that hard...

review: Disapprove

[Sam Spilsbury (smspillaz)]

I would however like to see a testing framework where we can load and unload unityshell in a sandbox (will require lots of work getting mock compiz objects and abstracting away the necessity for SubstructureRedirectMask).

review: Disapprove

[Alan Griffiths (alan-griffiths)]

A shortcut to a testing framework might be to run under xvfb and add a command line option to specify a plugin to be run through fini/init cycles?

[Daniel van Vugt (vanvugt)]

I was thinking the same. However I read recently that xvfb is being retired...

[Marco Trevisan (Treviño) (3v1n0)]

> I would prefer that we keep crashing so that Unity gets fixed, rather than hiding the crashes indefinitely.
> It's not impossible to fix them;

Thanks to the Brandon help, and after fixing libbamf we actually have unity not crashing. I can safely enable and disable it from ccsm.
So, I think that the main issues have been fixed.

Unmerged revisions

3110. By Alan Griffiths on 2012-04-23

Workaround for some SIGSEGV crashes

=== modified file 'src/screen.cpp'
--- src/screen.cpp	2012-04-20 09:58:29 +0000
+++ src/screen.cpp	2012-04-23 11:44:18 +0000
@@ -982,7 +982,17 @@
     {
 	for (pluginIndex = 0; pluginIndex < nPop; pluginIndex++)
 	{
-	    alreadyLoaded.push_back(CompPlugin::pop());
+	    CompPlugin* current = CompPlugin::pop();
+
+            if ("unityshell" == current->vTable->name())
+	    {
+		CompPlugin::unload(current);
+	    }
+	    else
+	    {
+		alreadyLoaded.push_back(current);
+	    }
+
 	    plugin.list().pop_back();
 	}
     }