Athena Developer Guide

Athena Chapter 5 Writing algorithms Version/Issue: 2.0.0
the Counter1 instance will report seeing 50% of the events, while the Counter2 instance will
report seeing 10%.
Note the same instance of the HelloWorld class appears in both sequences. It will be executed in
Sequence1 if Prescaler1 passes the event. It will be executed in Sequence2 if Prescaler2
passes the event only if Prescaler1 failed it.
Listing 5.3a Example job options using Sequencers demonstrating filtering
1: ApplicationMgr.DLLs += { "GaudiAlg" };
2: ApplicationMgr.TopAlg = { "Sequencer/TopSequence" };
3:
4: // Setup the next level sequencers and their members
5: TopSequence.Members = {"Sequencer/Sequence1", "Sequencer/Sequence2"};
6: TopSequence.StopOverride = true;
7: Sequence1.Members = {"Prescaler/Prescaler1", "HelloWorld",
"EventCounter/Counter1"};
8: Sequence2.Members = {"Prescaler/Prescaler2", "HelloWorld",
"EventCounter/Counter2"};
9:
10: Prescaler1.PercentPass = 50.;
11: Prescaler2.PercentPass = 10.;
Listing 5.3b Example Python script using Sequencers demonstrating filtering
1: theApp.DLLs = [ "GaudiAlg" ]
2: theApp.TopAlg = [ "Sequencer/TopSequence" ]
3: TopSequence = Algorithm( "TopSequence" )
4:
5: # Setup the next level sequencers and their members
6: TopSequence.Members = [ "Sequencer/Sequence1", "Sequencer/Sequence2"]
7: Sequence1 = Algorithm( "Sequence1" )
8: Sequence2 = Algorithm( "Sequence2" )
9: TopSequence.StopOverride = true
10: Sequence1.Members = [ "Prescaler/Prescaler1", "HelloWorld",
"EventCounter/Counter1" ]
11: Prescaler1 = Algorithm( "Prescaler1" )
12: Counter1 = Algorithm( "Counter1" )
13: Sequence2.Members = [ "Prescaler/Prescaler2", "HelloWorld",
"EventCounter/Counter2" ]
14: Prescaler2 = Algorithm( "Prescaler2" )
15: Counter2 = Algorithm( "Counter2" )
16:
17: Prescaler1.PercentPass = 50.
18: Prescaler2.PercentPass = 10.
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Sequence branching
Listing 5.4a and Listing 5.4b illustrate the use of explicit branching. The BranchMembers property
of the Sequencer specifies some algorithms to be executed if the algorithm that is the first member of
the branch (which is common to both the main and branch membership lists) indicates a filter failure. In