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/EventFormatReadTest_jobOptions.py

@@ -2,14 +2,26 @@
 
 # Read an input test file.
 import AthenaPoolCnvSvc.ReadAthenaPool
-ServiceMgr.EventSelector.InputCollections = [ 'EventFormatWriteTest.pool.root' ]
+
+ServiceMgr.EventSelector.InputCollections = ["testStream1.pool.root"]
+
+# Read in the metadata
+from AthenaCommon.AppMgr import ServiceMgr, ToolSvc
+ToolSvc += CfgMgr.xAODMaker__EventFormatMetaDataTool(
+    "EventFormatMetaDataTool"
+)
+ServiceMgr.MetaDataSvc.MetaDataTools += [ToolSvc.EventFormatMetaDataTool]
+
 
 # Access the main algorithm sequence.
 from AthenaCommon.AlgSequence import AlgSequence
+
 algSeq = AlgSequence()
 
 # Add the xAOD::EventFormat printer algorithm.
-algSeq += CfgMgr.xAODMakerTest__EventFormatPrinterAlg()
+algSeq += CfgMgr.xAODMakerTest__EventFormatPrinterAlg(
+    InputKey="FormattestStream1",
+)
 
 # Some extra job parameters.
 theApp.EvtMax = 1