Check for valid pointers in GetJetConstituentsQuick (Port of PR#7525 from 72X)

[heilman]

This was not ported forward from CMSSW_7_2_X. This change adds pointer checking to GetJetConstituentsQuick(). This prevents errors when looping over genJet constituents that have been dropped from miniAOD.

[cmsbuild]

A new Pull Request was created by @heilman for CMSSW_7_4_X.

Check for valid pointers in GetJetConstituentsQuick (Port of PR#7525 from 72X)

It involves the following packages:

DataFormats/JetReco

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
@rappoccio, @ahinzmann, @TaiSakuma, @jdolen, @nhanvtran, @schoef, @mariadalfonso this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
You can reject by replying to this message having '-1' in the first line of your reply.
If you are a L2 or a release manager you can ask for tests by saying 'please test' in the first line of a comment.
@Degano you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[cvuosalo]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

+1
Tested at: 8bcca51
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-9638/5507/summary.html

[cvuosalo]

+1

For #9638 8bcca51

Adding a check for a valid pointer to Jet::GetJetConstituentsQuick. No change in monitored quantities would be expected. The 75X forward port of this PR,, #9637, has already been approved by Reco.

The code changes are satisfactory. Jenkins tests against baseline CMSSW_7_4_X_2015-06-15-1100 show no significant differences, except for workflow 140.53_RunHI2011, which shows a few differences for akPu3PFJets. However, repeated tests of this workflow against baseline CMSSW_7_4_2 fails to consistently reproduce the problem, as discussed for the previous version of this PR, #9539. Also, workflow 140.0_HydjetQ_MinBias with 30 events shows no differences. And the 75X Jenkins tests for the companion PR #9637 show no similar differences. The missing jets problem in the HI workflow appears to be an intermittent 74X issue not related to this PR.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs once checked with relvals in the development release cycle of CMSSW (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1