Athena Developer Guide

More documents

Recommendations

Info

$' \^' I$

Athena Chapter 5 Writing algorithms Version/Issue: 2.0.0 Algorithm sysInitialize setProperties initialize createSubAlgorithm "create" SubAlgorithm createSubAlgorithm "create" SubAlgorithm Te xt sysInitialize setProperties initialize sysInitialize setProperties initialize Figure 5.1 Algorithm initialization. application manager. For sub-algorithms (see section 5.4) the control flow may be as you like: you may call the execute() method once, many times or not at all. page 28
Athena Chapter 5 Writing algorithms Version/Issue: 2.0.0 Just because an algorithm derives from the Algorithm base class does not mean that it is limited to using or overriding only the methods defined by the base class. In general, your code will be much better structured (i.e. understandable, maintainable, etc.) if you do not, for example, implement the execute() method as a single block of 100 lines, but instead define your own utility methods and classes to better structure the code. If an algorithm fails in some manner, e.g. a fit fails to converge, or its data is nonsense it should return from the execute() method with StatusCode::FAILURE. This will cause the application manager to stop processing events and end the job. This default behaviour can be modified by setting the .ErrorMax job option to something greater than 1. In this case a message will be printed, but the job will continue as if there had been no error, and just increment an error count. The job will only stop if the error count reaches the ErrorMax limit set in the job option. The framework (the Algorithm base class) calls the execute() method within a try/catch clause. This means that any exception not handled in the execution of an Algorithm will be caught at the level of sysExecute() implemented in the base class. The behaviour on these exceptions is identical to that described above for errors. Finalization The finalize() method is called at the end of the job. It can be used to analyse statistics, fit histograms, or whatever you like. Similarly to initialization, the framework invokes a sysFinalize() method which in turn invokes the finalize() method of the algorithm and of any sub-algorithms. Monitoring of the execution (e.g. cpu usage) of each Algorithm instance is performed by auditors under control of the Auditor service (described in Chapter 13). This monitoring can be turned on or off with the boolean properties AuditInitialize, AuditExecute, AuditFinalize. The following is a list of things to do when implementing an algorithm. • Derive your algorithm from the Algorithm base class. • Provide the appropriate constructor and the three methods initialize(), execute() and finalize(). • Make sure you have implemented a factory by adding the magic two lines of code (see 5.3.1). 5.4 Nesting algorithms The application manager is responsible for initializing, executing once per event, and finalizing the set of top level algorithms, i.e. the set of algorithms specified in the job options file. However such a simple linear structure is very limiting. You may wish to execute some algorithms only for specific types of event, or you may wish to “loop” over an algorithm’s execute method. Within the Athena application framework the way to have such control is via the nesting of algorithms or through algorithm sequences (described in section 5.5). A nested (or sub-) algorithm is one which is created by, and thus belongs to and is controlled by, another algorithm (its parent) as opposed to the application manager. In this section we discuss a number of points which are specific to sub-algorithms. page 29
Page 1 and 2: ATLAS Athena The ATLAS Common Frame
Page 3 and 4: Athena Table of Contents Version/Is
Page 9 and 10: Athena Chapter 1 Introduction Versi
Page 11 and 12: Athena Chapter 1 Introduction Versi
Page 13 and 14: Athena Chapter 2 The framework arch
Page 19 and 20: Athena Chapter 3 Release notes Vers
Page 21 and 22: Athena Chapter 4 Establishing a dev
Page 23 and 24: Athena Chapter 5 Writing algorithms
Page 27: Athena Chapter 5 Writing algorithms
Page 35 and 36: Athena Chapter 6 Scripting Version/
Page 43 and 44: Athena Chapter 7 Accessing data Ver
Page 55 and 56: Athena Chapter 8 StoreGate - the ev
Page 69 and 70: Athena Chapter 9 Data dictionary Ve
Page 75 and 76: Athena Chapter 10 Detector Descript
Page 77 and 78: Athena Chapter 11 Histogram facilit
Page 79 and 80:
Athena Chapter 11 Histogram facilit
Page 81 and 82:
Athena Chapter 11 Histogram facilit
Page 83 and 84:
Athena Chapter 12 N-tuple and Event
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Athena Chapter 13 Framework service
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Athena Chapter 14 Tools and ToolSvc
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Athena Chapter 15 Converters Versio
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Athena Chapter 16 Visualization Ver
Page 149 and 150:
Athena Chapter 17 Physical design i
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Athena Chapter 18 Framework package
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Athena Chapter 19 Analysis utilitie
Page 171 and 172:
Athena Version/Issue: 2.0.0 Appendi
Page 173 and 174:
Athena Appendix B Options for stand
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Athena Appendix C Design considerat
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Athena Version/Issue: 2.0.0 Appendi
Page 189 and 190:
Athena Version/Issue: 2.0.0 19.6.6
Page 191 and 192:
Athena Version/Issue: 2.0.0 A AIDA
Page 193 and 194:
Athena Version/Issue: 2.0.0 of N-tu
Page 195:
Athena Version/Issue: 2.0.0 ROOT 17
show all

Athena Developer Guide

Create successful ePaper yourself

Delete template?

Save as template?