Merge lp:~vanvugt/mir/fix-1671033 into lp:mir

[Daniel van Vugt]

Optimize a crazily inefficient test case (LP: #1671033)

Not a threading problem this time, but a general algorithmic complexity
problem. The test itself was running 50x longer than it needs to, and
the FakeAlarmFactory class it uses was copying a vector 3 million times during the one test case (now zero times).

Execution times under valgrind:
Before: 30 seconds; After: 0.7 seconds

Execution times natively:
Before: 0.8 seconds; After: 0.01 seconds

Note the above times are from a fast Xeon. CI logs show the test was taking minutes in CI.

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:4087
https://mir-jenkins.ubuntu.com/job/mir-ci/3148/
Executed test runs:
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-mir/4227
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/4314
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/4304
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial+overlay/4304
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=zesty/4304
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4254/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4254/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4254/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4254/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4254/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4254
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4254/artifact/output/*zip*/output.zip

Click here to trigger a rebuild:
https://mir-jenkins.ubuntu.com/job/mir-ci/3148/rebuild

review: Approve (continuous-integration)

[Alan Griffiths (alan-griffiths)]

OK

review: Approve

=== modified file 'tests/mir_test_doubles/fake_alarm_factory.cpp'
--- tests/mir_test_doubles/fake_alarm_factory.cpp	2017-01-18 02:29:37 +0000
+++ tests/mir_test_doubles/fake_alarm_factory.cpp	2017-03-14 10:11:45 +0000
@@ -155,11 +155,13 @@
 void mtd::FakeAlarmFactory::advance_by(mt::Duration step)
 {
     clock->advance_by(step);
-    // Guard against alarms deleting themselves from their callback...
-    auto temp_alarms = alarms;
-    for (auto& alarm : temp_alarms)
+    for (unsigned i = 0u; i < alarms.size();)
     {
-        alarm->time_updated();
+        auto const old_size = alarms.size();
+        alarms[i]->time_updated();
+        // Guard against alarms deleting themselves from their callback...
+        if (alarms.size() >= old_size)
+            ++i;
     }
 }
 

=== modified file 'tests/unit-tests/scene/test_mediating_display_changer.cpp'
--- tests/unit-tests/scene/test_mediating_display_changer.cpp	2017-03-13 08:12:52 +0000
+++ tests/unit-tests/scene/test_mediating_display_changer.cpp	2017-03-14 10:11:45 +0000
@@ -1022,7 +1022,7 @@
 
     changer->confirm_base_configuration(mock_session, new_config);
 
-    alarm_factory.advance_smoothly_by(timeout * 100);
+    alarm_factory.advance_smoothly_by(timeout * 2);
     EXPECT_THAT(*applied_config, mt::DisplayConfigMatches(std::cref(*new_config)));
 }