Event format meta data

Picking up from the discussion at !33803 (closed)

@akraszna implemented a very nice start to handling xAOD::EventFormat metadata in athenaMT. @gemmeren Pointed out that we should adopt a uniform approach to handling EventStreamInfo and xAOD::EventFormat. This leaves some approaches:

• Write multithreaded service maintaining one shared EventStreamInfo object in a thread-safe manner.
• Maintain a xAOD::EventFormat object for each output stream.
• Something we have not yet thought of Here we choose the second, i.e. maintain a xAOD::EventFormat object for each output stream. That means the key of the xAOD::EventFormat object now is a function of the stream name. Trying to adopt the EventStreamInfo style I went for something like:

AthenaOutputStream(
    name=name,
    HelperTools=[
        CfgMgr.xAODMaker__EventFormatStreamHelperTool(
            name="EventFormatStreamHelper"
            Key='Format{}'.format(name),
        ),
    ],
)

Of course any client looking up xAOD::EventFormat by key will have to adjust for that, as you can see in the read test. How much of a nightmare will this be?

I have not yet included recording and retrieving xAOD::EventFormat though the MetaDataSvc as implemented for EventStreamInfo. Is that desirable @mnowak

As you can see by the hacky approach and the title this is still a construction site and needs cleaning up.

Thoughts?

@tsulaia

Event/xAOD/xAODEventFormatCnv/share/EventFormatReadWriteJobOptions.py

+# Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+"""Test writing xAOD::EventFormat in job reading from input
+
+Read in POOL files created by the write test job options. Uses the metadata
+tool to transcribe the EventFormat metadata to the MetaDataStore. Then an
+algorithm reads the EventFormat from the MetaDataStore and prints the content.
+
+    Typical usage example
+        1. run: athena xAODEventFormatCnv/EventFormatWriteTestJobOptions.py
+        2. run: athena xAODEventFormatCnv/EventFormatReadWriteTestJobOptions.py
+"""
+from AthenaCommon import CfgMgr
+from AthenaCommon.AlgSequence import AlgSequence
+from AthenaCommon.AppMgr import ServiceMgr as svcMgr
+from AthenaCommon.AppMgr import theApp
+from AthenaCommon.AppMgr import ToolSvc
+import AthenaPoolCnvSvc.ReadAthenaPool
+from xAODEventInfoCnv.xAODEventInfoCreator import xAODMaker__EventInfoCnvAlg
+from OutputStreamAthenaPool.MultipleStreamManager import MSMgr
+
+VERBOSE = 1
+DEBUG = 2
+INFO = 3
+NUMBER_OF_STREAMS = 1
+
+
+def makeStream(name='TestStream'):
+    """create and return an output stream"""
+    test_stream = MSMgr.NewStream(
+        StreamName=name,
+        FileName="{}.pool.root".format(name),
+        noTag=True,
+    )
+    # Add dummy items for testing
+    test_stream.AddItem("xAOD::ElectronContainer#TestElectrons")
+    test_stream.AddItem("xAOD::ElectronAuxContainer#TestElectronsAux.")
+    return test_stream
+
+
+# grab input files
+svcMgr.EventSelector.InputCollections = [
+    "testStream0.pool.root",
+    "testStream1.pool.root",
+]
+
+# propogate xAOD::EventFormat from InputMetaDataStore to MetaDataStore
+ToolSvc += CfgMgr.xAODMaker__EventFormatMetaDataTool(
+    "EventFormatMetaDataTool",
+    OutputLevel=VERBOSE,
+)
+svcMgr.MetaDataSvc.MetaDataTools += [ToolSvc.EventFormatMetaDataTool]
+
+
+# Add the xAOD::EventFormat printer algorithm to main algorithm sequence
+algSeq = AlgSequence()
+algSeq += CfgMgr.xAODMakerTest__EventFormatPrinterAlg()
+
+
+# Add (an) xAOD creator algorithm(s) to the job.
+algSeq += CfgMgr.xAODMakerTest__ElectronCreatorAlg(
+    "ElectronCreator", OutputKey="TestElectrons2"
+)
+
+# Write some output streams to file with this container.
+streams = [
+    makeStream('readWriteTestStream{}'.format(i)) for i in range(NUMBER_OF_STREAMS)
+]
+
+# Make sure event info is available
+algSeq += xAODMaker__EventInfoCnvAlg()
+
+svcMgr.MessageSvc.OutputLevel = INFO
+svcMgr.MetaDataSvc.OutputLevel = DEBUG
+
+# read the last event of the first file and the first event of the second file
+# to test metadata access across file boundary
+theApp.EvtMax = -1