GaudiAlgorithm

Class Description

The GaudiAlgorithm class is an extension to the basic Gaudi Algorithm class. It provides additional shortcut methods for things such as :-

• Simple and safe location of services and tools
• Easy messaging and exception handling
• Easy handling of statistical counters

Locating Tools and Services

If one inherits the code from the base classes GaudiAlgorithm or GaudiTool, one can locate tools in a very simple way using the templated method tool:

 1000// locate the private tool using type and name:
 1010IMyTool* mytool1  = tool<IMyTool>("MyToolType","MyToolName", this ) ;
 1020
 1030// locate the private tool using "type/name" semantic:
 1040IMyTool* mytool2  = tool<IMyTool>("MyToolType/MyToolName"  , this ) ;
 1050
 1060// locate the public tool using type and name:
 1070IMyTool* mytool3  = tool<IMyTool>("MyToolType","MyToolName" ) ;
 1080
 1090// locate the public tool using "type/name" semantic:
 1100IMyTool* mytool4  = tool<IMyTool>("MyToolType/MyToolName"  ) ;
 1110
 1120// locate the public tool using ":PUBLIC" keyword
 1130IMyTool* mytool5 = tool<IMyTool>("MyToolType","MyToolName:PUBLIC", this ) ;
 1140
 1150// locate the public tool using "type/name" semantic with ":PUBLIC" keyword:
 1160IMyTool* mytool6  = tool<IMyTool>("MyToolType/MyToolName:PUBLIC"  , this ) ;

There is no need to release the acquired tools, all acquired tools will be properly released in the finalize method of the base class.

Similar methods exist for the easy location of services using similar semantics to tools:

 1000// locate the service by name, create if needed.. 
 1010IMyService* s = svc<IMyService>( "MyServiceType" , true ) ;

These methods throw exception if the required tool or service is not found, therefore there is no need to check the returned pointer - the system ensures its validity.

Using the predefined message streams

The base classes GaudiAlgorithm and GaudiTool predefine a set of methods for easy control of printout:

 1000// print as MSG::VERBOSE 
 1010verbose() << " It is VERBOSE printout " << endmsg ;
 1020
 1030// print as MSG::DEBUG
 1040debug()   << "It is DEBUG   printout" << endmsg ;
 1050
 1060// print as MSG::INFO
 1070info()    << "It is INFO    printout" << endmsg ;
 1080
 1090// ditto 
 1100msg()    << "Is it INFO    printout" << endmsg ;
 1110
 1120// print as MSG::WARNING 
 1130warning() << "It is WARNING printout" << endmsg ;
 1140
 1150// print as MSG::ERROR 
 1160error()   << "It is ERROR   printout" << endmsg ;
 1170
 1180// ditto
 1190err()     << "It is ERROR  printout" << endmsg ;
 1200
 1210// print as MSG::FATAL
 1220fatal()   << "It is FATAL printout" << endmsg ;
 1230
 1240// print as MSG::ALWAYS
 1250always()  << "It is ALWAYS  printout" << endmsg ;
 1260
 1270// print with the specified level:
 1280MSG::Level level = ... ;
 1290msgStream ( level ) << "It is custom  printout" << endmsg ;

The usage of these predefined methods decreases significantly the CPU penalty for creation/destruction of local MsgStream objects. However some penalty for deactivated streams is still visible, e.g. see the discussion around Savannah patch #1196 by Patrick Koppenburg. In short, one should avoid the unchecked usage of the streams, especially for inner loops. It is recommended to check the status of the stream with the msgLevel before actual usage of the stream:

 1000for ( long i = 0 ; i < 1000000 ; ++ i )
 1010{
 1020    // bad style, not efficient:
 1030    verbose() << " some printout " << .... << endmsg ;  ///< very bad!, not efficient!
 1040    
 1050    // good style, efficient:
 1060   if ( msgLevel  ( MSG::VERBOSE ) )  {  verbose () << " another printout " << ... << endmsg ; } ///< GOOD STYLE, EFFICIENT
 1070
 1080}

Using the generic statistical counters

The GaudiAlgorithm and GaudiTool base classes are equipped with the method counter, which returns a reference to the local instance of the named counter (C++ type StatEntity&):

 1000const std::size_t nTracks = ... ;
 1010
 1020// increment the counter:
 1030counter("#Tracks")+= nTracks ;

The current content of the generic counter could be inspected:

 1000const StatEntity& cnt = ... ;
 1010always() 
 1020    << " #of entries " << cnt.nEntries() << endmsg 
 1030    << " Total sum   " << cnt.flag()         << endmsg
 1040    << " Mean value  " << cnt.flagMean () << endmsg
 1050    << " RMS "  << cnt.flagRMS() << endmsg
 1060    << " Minimal value " << cnt.flagMin() << endmsg
 1070    << " Maximal value " << cnt.flagMax () << endmsg ;  

If the content of the generic counter allows the interpretation as a binominal efficiency counter one can ask for efficiency and its uncertainty:

 1000always() 
 1010    << " Efficiency " << cnt.eff() 
 1020    << " +-"          << cnt.effErr()     << endmsg;

All counters will be printed at the end of the job in a table if the property "StatPrint" is activated (default):

Counter           SUCCESS Number of counters : 8
Counter           SUCCESS      Counter     |     #     |    sum     | mean/eff^* | rms/err^*  |     min     |     max     |
Counter           SUCCESS  "G"             |     26490 |   -326.309 |  -0.012318 |    0.99484 |     -3.8836 |      3.8273 |
Counter           SUCCESS  "Gneg"          |      2712 |       2712 |     1.0000 |    0.00000 |      1.0000 |      1.0000 |
Counter           SUCCESS  "Gpos"          |      2688 |       2688 |     1.0000 |    0.00000 |      1.0000 |      1.0000 |
Counter           SUCCESS  "NG"            |     26490 |      26490 |     1.0000 |    0.00000 |      1.0000 |      1.0000 |
Counter           SUCCESS *"eff"           |      5400 |       2688 |( 49.77778 +- 0.6804071)%|   -------   |   -------   |
Counter           SUCCESS  "executed"      |      5400 |       5400 |     1.0000 |    0.00000 |      1.0000 |      1.0000 |
Counter           SUCCESS  "g2"            |      5400 |   5341.386 |    0.98915 |     1.3535 | 1.8914e-006 |      13.130 |
Counter           SUCCESS  "gauss"         |      5400 |  -8.611382 | -0.0015947 |    0.99456 |     -3.6235 |      3.5079 |

Why are some counters printed with ------ symbols as min/max values and their names are prepended with asterisks ?

the counter is printed as the binomial efficiency counter using the special format if:

1. the name of the counter contains (case-insentitive) substrings "eff", "acc", "pass", "filt" or "fltr".
2. the content of the counter could be interpreted as the binomial efficiency counter (see here)
3. the property UseEfficiencyRowFormat is activated, see (see here).

How can I change the format of the final table of the counters?

The format of the final table is under the control of following properties:

Property	Type	Description
StatTableHeader	string	The string to be used as the header of the table
RegularRowFormat	string	The format to be used for the regular counters
EfficiencyRowFormat	string	The special format to be used for the binomial efficiency counters
UseEfficiencyRowFormat	true	Switch on/off the special treatment for the binomial efficiency counters

The formatting is performed using Boost Format Library.

Doxygen Documentation

http://proj-gaudi.web.cern.ch/proj-gaudi/releases/latest/doxygen/class_gaudi_algorithm.html

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ChrisRJones - 29 Jul 2005

MarcoCattaneo - 20 Mar 2009