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ATLAS Offline Software
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ATLAS Offline Software
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AthenaPoolUtilities is a package containing tools for using POOL persistency software with Athena. Presently it contains CMT patterns for generating POOL converters, iohandlers for element links, and some command line tools for accessing and managing POOL collections and metadata. This package also contains a class AthenaAttributeList which is an Athena adapter for [[http://pool.cern.ch/releases/POOL_2_0_0/doc/classReference/html/AttributeList_8cpp-source.html][AttributeList]] and is described below. Finally, there are a number of POOL Collection utilities whose use are as well described below.
15 August 2003 RDS
This is a brief how-to which explains how to generate the pool converters for one or more data packages. (See the corresponding how-to in the AtlasSEAL package for how to generate a SEAL dictionary for you data classes.)
Pool converters are automatically generated using a cmt pattern. By convention, the generation is done in a single package for a number of classes. For example, the InDet Event classes are done in the InnerDetector/InDetEventCnv/InDetEventAthenaPool package. We use this package as an example.
1) Rule 1: each class must be declared in a separate .h file. For example, InDetRawData/PixelRDO_Container.h holds the definition of only the PixelRDO Container.
2) In the requirements file of converter package one has:
package InDetEventAthenaPool
author Davide Costanzo <Davide.Costanzo@cern.ch>
use AtlasPolicy AtlasPolicy-*
use AthenaPoolUtilities AthenaPoolUtilities-00-* Database/AthenaPOOL
use InDetRawData InDetRawData-01-* InnerDetector/InDetRawEvent
# temporarily add in explicit link to dictionary
macro_append InDetEventAthenaPool_linkopts " -lInDetRawDataDict "
apply_pattern poolcnv files="-s=${InDetRawData_root}/InDetRawData \
PixelRDO_Container.h SCT_RDO_Container.h TRT_RDO_Container.h "
The "use AthenaPoolUtilities" is needed to get the poolcnv pattern. The other users should refer to packages with data objects which need converters.
One should provide the list of header files for the pattern "poolcnv". These can be taken from a number of packages following the syntax of
"-s=${<package>_root}/<package> <hdr1> hdr2>"
which can be repeated.
The necessary "uses" should be done to the packages with the header files.
Finally, one should temporarily link against the dictionary libraries containing the object descriptions needed by the converter. This is done by adding the library names in the list of <package>_linkopts as seen above. Note that this will be automated in the future so that the dictionaries will be loaded when needed. When this happens the <package>_linkopts will need to be removed.
The class AthenaAttributeList is used to set the Tag in an Event Collection. An !AttributeList represents a logical row of attributes in a metadata table. The name and type of each attribute is given in an AttributeListSpecification. AthenaAttributeList is an !AttributeList which is also a DataObject and thus can be saved in an Athena data store, e.g. the Event Store. The classes [[http://pool.cern.ch/releases/POOL_2_0_0/doc/classReference/html/classpool_1_1AttributeList.html][AttributeList]] and [[http://pool.cern.ch/releases/POOL_2_0_0/doc/classReference/html/classpool_1_1AttributeListSpecification.html][AttributeListSpecification]] are defined in POOL (and eventually in SEAL).
This package contains 2 classes that are used in Athena TP-separated persistent data model: TPObjRef and TPCnvTokenList_p1.
TPObjRef is used to replace object composition constructs existing in the transient data model: pointers, inheritance and embedding. A TP converter toPersistent() method will create a persistent representation, store it in the top-level persistent object and return TPObjRef, which can be persistified. When reading, the TPObjRef is used to locate the persistent representation and convert it to transient.
TPCnvTokenList_p1 is used in case a top-level persistent object needs to be extended. The extensions are written as separate POOL objects and tokens referencing these objects are kept in the principal top-level object in a data member of TPCnvTokenList_p1 type.
Full description of the TP separation used in Athena can be found on the Wiki page: https://twiki.cern.ch/twiki/bin/view/Atlas/TransientPersistentSeparation
1.8.18