Merge lp:~michihenning/unity-scopes-api/cpu-fix into lp:unity-scopes-api

[Michi Henning]

Fix to stop SignalThread from spinning if waitpid() is called at a point where there are no child processes.

Fix to stop SignalThread from spinning if waitpid() is called at a point where there are no child processes.

Please let's merge this before Jussi's branch for the new registry. Jussi's branch doesn't use SignalThread, but I don't want to have the last checked-in version of SignalThread harbor a bug, in case we want to resurrect that class at some point in the future.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:128
http://jenkins.qa.ubuntu.com/job/unity-scopes-api-ci/231/
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    SUCCESS: http://jenkins.qa.ubuntu.com/job/unity-scopes-api-trusty-armhf-ci/231
        deb: http://jenkins.qa.ubuntu.com/job/unity-scopes-api-trusty-armhf-ci/231/artifact/work/output/*zip*/output.zip
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review: Approve (continuous-integration)

[Michal Hruby (mhr3)]

Looks fine. +1

review: Approve

=== modified file 'scoperegistry/SignalThread.cpp'
--- scoperegistry/SignalThread.cpp	2013-11-21 21:44:00 +0000
+++ scoperegistry/SignalThread.cpp	2014-01-15 06:30:02 +0000
@@ -134,6 +134,10 @@
                             cerr << "scoperegistry: wait() failed: " << strerror(errno) << endl;
                             _exit(1);
                         }
+                        if (errno == ECHILD)
+                        {
+                            break;  // We don't have any sub-processes
+                        }
                         continue; // Ignore stray SIGCHLD signals
                     }
                     if (pid == 0)