fix vertex loop in PFPhotonIsolationCalculator

[VinInn]

Removed an "obfuscated" nested loop.
also profit of the new template interface to remove RefBase churn...
(still, it is looping on all the tracks in all the vertices for each charged particle...)

accounting for more than 1% of the time in Reco 40PU25ns TTBAR
http://innocent.web.cern.ch/innocent/perfResults/igprof-navigator/TTBAR_step3_ori_CMSSW_7_1_X_2014-04-05-1400_slc6_amd64_gcc490/190

No regression expected. No regression observed

[cmsbuild]

A new Pull Request was created by @VinInn (Vincenzo Innocente) for CMSSW_7_1_X.

fix vertex loop in PFPhotonIsolationCalculator

It involves the following packages:

RecoEgamma/PhotonIdentification

@nclopezo, @cmsbuild, @anton-a, @thspeer, @slava77, @Degano can you please review it and eventually sign? Thanks.
@lgray 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.
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@nclopezo, @ktf you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[cmsbuild]

Pull request #3279 was updated. @nclopezo, @monttj, @cmsbuild, @anton-a, @thspeer, @slava77, @vadler, @Degano can you please check and sign again.

[cmsbuild]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-3279/861/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-3279/861/summary.html

[vadler]

+1

[slava77]

+1

for #3279 77cb53a
tested in CMSSW_7_1_X_2014-04-12-1400 (test area sign341 in a combination of
3247 3272 3261 3277 3279 3292
no regressions

timing improvements confirmed

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_1_X IBs unless changes (tests are also fine). @nclopezo, @ktf can you please take care of it?