AliRoot IO and Folder

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AliRoot I/O and Folder

• Alice Offline-Week 10-15 V 2002
• Piotr Krzysztof Skowronski
• June 11, 2002

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Goal

• All data types goes to the separate file.
• Each event is stored in separate root-directory
  within root file
• One tree per event for each data type no event
  number embedded in the tree name
• Data exchange through folders.

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galice.root
RunLoader
TreeE
Tree
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Idea of Loaders

• Loader is an object responsible for
  openning/closing files
• Manages files and directory (OS as well as ROOT)
  names
• Posting data
• from file to folder reading
• and vice versa - writing
• Plus some shortcut methods for accessing data
  from folders
• e.g instead of calling dynamic_castltTTreegt(fEven
  tFolder-gtFindObject(fgkHeaderContainerName))each
  time, one can useloader-gtTreeH()

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Two types of loaders

• Run Loader (AliRunLoader)
• Manages all central data
• AliRun - gAlice
• Header TreeE
• Kinematics - TreeK
• Track References - TreeTR
• Run Loader itself
• Detector Loader (AliLoader)
• Manages all data related to each detector
• Hits TreeH
• Summable Digids TreeS
• Digits TreeD
• Reconstructed Points TreeR
• Tracks TreeT

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AliLoader

• AliLoader implements all standard functionality
  However if any detector needs other behaviour of
  loader than standard it should create detector
  specific loader and overload proper methods
• The same applies if extensions are needed
• See example of AliPHOSLoader

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AliRunLoader

• Decouples all I/O management from AliRun
• It stays itself in folder as well
• Is written to galice.root as an object
• Manages event reloading (as an only one object in
  aliroot)
• Is an owner of AliStack and AliHeader
• Is responsible for reloading events

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Architecture

• AliRunLoader is a central I/O manager
• It is created in Config.C and set to gAlice
  object
• AliRunLoader has a list of AliLoaders
• Each detector registers its loader during MC
  initialization
• Detector itself stores the pointer to its loader
• Faster data access
• If detector is read from file, it gets pointer to
  its loader automatically
• AliDetector is not owner of loader!

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Usage

• Each session should be started from loading
  RunLoader itselfstatic AliRunLoader
  AliRunLoaderOpen(const char filename
  "galice.root", const char eventfoldername
  AliConfigfgkDefaultEventFolderName,
  Option_t option "READ")For
  exampleAliRunLoader rl AliRunLoaderOpen("gal
  ice.root","MyFolder","READ")if (rl 0x0)
  cerrltlt"Can not open session for file
  galice.root" return

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AliRunLoaderOpen

• This method tries
• to open file in mode specified by option
• Find the run loader object in file
• If file option is new, create or recreate
  it creates new AliRunObject instead
• Calls AliConfigBuildEventFolder to create
  folder structure for event
• Puts AliRunLoader in folder and returns pointer
  to it
• In case of error returns NULL

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Usage cont. (AliRunLoader)

• In order to load data
• LoadgAlice loads AliRun
• LoadHeader Loads TreeE, creates AliHeader, sets
  address in tree and gets header for current event
• LoadKinematics Opens kine file, posts TreeK for
  current event to folder. If header loaded calls
  AliStackGetEvent which connects Tree.
• LoadTrackRefs Opens file with track references
  and puts them in folder

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Usage cont. (AliRunLoader)

• To write data, call
• WriteKinematics
• WriteHeader
• WriteTrackRefs
• Tu unload data
• UnloadKinematics
• UnloadHeader
• UnloadTrackRefs
• UnloadgAlice

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Usage cont. (AliLoader)

• To load detector specific data call following
  methods
• LoadHits loads hits for given detector
• LoadSDigits loads summable digits
• LoadDigits
• LoadRecPoints
• LoadTracks
• All methods above takes Option_t as a parameter,
  which is passed to TFileOpen

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Usage cont. (AliLoader)

• To write detector specific data call following
  methods
• WriteHits writes hits for given detector
• WriteSDigits writes summable digits
• WriteDigits
• WriteRecPoints
• WriteTracks
• They take option, which can be OVERWRITE to
  force overwriting

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Usage cont.

• To unload call UnloadDataType e.g.
• UnloadHits
• To make new container (tree) call
  MakeDataTypeContainer
• e.g.
• AliLoaderMakeHitsContainer
• AliRunLoaderMakeKineContainer
• Old style MakeTree(Option_t) is supported as
  well
• AliRunLoaderMakeTree(K) makes TreeK
• AliRunLoaderMakeTree(H) makes TreeH for all
  loaders in the list
• AliLoaderMakeTree(D) makes TreeD for only
  one detector
• However it does not support option TR since it
  will be recognized as Track Tree and
  Recostruction Tree

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Usage cont.

• To get access to data (trees) one can use
  shortcut methods like
• AliLoaderTreeH()
• AliLoaderTreeS()
• AliRunLoaderTreeK()
• AliRunLoaderTreeE()

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Usage cont. (AliRunLoader)

• To get loader for specific detector use
• AliLoader GetLoader(const char name)
• AliLoader GetLoader(AliDetector name)
• Getting event AliRunLoaderGetEvent(Int_t)
• Reloads all loaded data, for exampleAliRunLoader
  rl AliRunLoaderOpen("galice.root","MyFolder
  ","READ")rl-gtGetEvent(0)//(1) redundant
  default is event 0rl-gtLoadKinematics("READ")//(2
  )-loads kinematicsAliLoader tpcloader
  rl-gtGetLoader("TPCLoader")//(3)tpcloader-gtLoadDi
  gits("RECREATE")//(4)-loads Digits for
  TPCrl-gtGetEvent(1)//(5)
• At the moment of loading data (2),(3),(4) they
  are loaded for event 0 (current event). GetEvent
  in line (5) causes that all loaded data are
  reloaded for event 1.

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Usage cont. (AliRunLoader)

• To load detector data you can use
  methodAliRunLoaderLoadDataType (Option_t
  detectors"all", Option_t opt"READ")eg
• AliRunLoaderLoadHits() calls LoadHits("READ")
  for all loaders
• AliRunLoaderLoadHits("TPC ITS PHOS") calls
  LoadHits("READ") for TPC, ITS and PHOS laoders
• AliRunLoaderLoadHits("all","update") calls
  LoadHits("update") for all loaders

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Status

• New I/O version is merged with v3-08-02
• It compiles for all detectors but EMCAL
• TPC even works up to tracking
• Take it as a practical example
• display.C works as well
• I already wrote some documentation up to now
  rather poor however...http//alisoft.cern.ch/peop
  le/skowron/codedoc/split

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Substitutions

• AliRunGetEvent(Int_t)
• AliRunStack()
• AliRunGetHeader()
• AliRunTreeK()
• AliRunTreeE()
• AliRunTreeH()
• AliRunTreeS()
• AliRunTreeD()
• AliRunTreeR()

• AliRunLoaderGetEvent(Int_t)
• AliRunLoaderStack()
• AliRunLoaderGetHeader()
• AliRunLoaderTreeK()
• AliRunLoaderTreeE()
• AliLoaderTreeH()
• AliLoaderTreeS()
• AliLoaderTreeD()
• AliLoaderTreeR()

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Clue

• How to get access to Run Loader?
• Add a data member with folder name
• In AliDetector is not needed it already have
  pointer to its AliLoader.
• AliRunLoader is easily accessible from folder
  using static method
• AliRunLoader AliRunLoader
  GetRunLoader(const char eventfoldername)
• Set the event folder name from the place you open
  session macro, manager or superior class

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Example

• AliRunLoader rl AliRunLoaderOpen("galice.root
  ","Event",read")
• rl-gtLoadgAlice()
• gAlice rl-gtGetAliRun()//!!!!!!!!!!!!!!!!!!!!!!!
  !!!!!!!!
• AliTPC TPC (AliTPC)gAlice-gtGetDetector("TPC")
  
• AliLoader tpcl rl-gtGetLoader("TPCLoader")
• tpcl-gtLoadHits("READ")
• tpcl-gtLoadSDigits("RECREATE")
• Int_t nevent rl-gtGetNumberOfEvents()
• for(Int_t eventn 0eventnltneventeventn)
• rl-gtGetEvent(eventn)
• TPC-gtHits2SDigits2(eventn)
• tpcl-gtWriteSDigits(OVERWRITE)
• delete rl