avoid copies of GenEvent and optimizing random number usage in DIGI step

[davidlange6]

Roughly 10% improvement in mixing module time

Main change are:

1. Avoid copying GenEvent when not needed

2. Avoid creating a random generator using it once. I'm lazy so used the static methods as done elsewhere in the digitizers. One can easily also make the RandPoissonQ object a member data with the same effect. RandPoissonQ does some setup assuming that the mu its given will be used over and over, so there is a CPU penalty for creating it and using it only once.

[cmsbuild]

A new Pull Request was created by @davidlange6 (David Lange) for CMSSW_7_5_X.

avoid copies of GenEvent and optimizing random number usage in DIGI step

It involves the following packages:

SimCalorimetry/CaloSimAlgos
SimGeneral/PileupInformation
SimTracker/Common

@cmsbuild, @civanch, @nclopezo, @mdhildreth can you please review it and eventually sign? Thanks.
@jlagram, @makortel, @GiacomoSguazzoni, @gbenelli, @rovere, @VinInn, @appeltel, @cnuttens, @prolay, @cerati, @venturia, @threus, @dgulhan, @LBeck this is something you requested to watch as well.
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[cmsbuild]

-1
@davidlange6 This pull request cannot be automatically merged, could you please rebase it?

[davidlange6]

@cmsbuild, please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

-1
@davidlange6 This pull request cannot be automatically merged, could you please rebase it?

[ghost]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[civanch]

+1

[civanch]

all tests are fail - it is not problem of this PR but IB itself

[civanch]

@cmsbuild , several tests failed yesterday for various PRs which are obviously correct, should we restart these tests now or wait a bit ?

[nclopezo]

Hi @civanch,

I will restart them.

[cmsbuild]

+1
Tested at: a2c40e4
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8450/3733/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[davidlange6]

+1