FastTimerService: avoid race condition across different threads when updating summary information

[fwyzard]

No description provided.

[cmsbuild]

A new Pull Request was created by @fwyzard (Andrea Bocci) for CMSSW_7_1_X.

FastTimerService: avoid race condition across different threads when updating summary information

It involves the following packages:

HLTrigger/Timer

@perrotta, @cmsbuild, @nclopezo, @Martin-Grunewald, @fwyzard, @Degano can you please review it and eventually sign? Thanks.
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@nclopezo, @ktf you are the release manager for this.
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[fwyzard]

This should fix a race condition where different threads would update the summary information at the same time, possibly resulting in a corrupted summary.

Helgrind does not spot any other problems...

[cmsbuild]

+1
Tested at: cfd4f40
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-4257/1705/summary.html

[fwyzard]

+1

[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?