PyDBObj Class Reference

Class to access a DBObjPtr from Python. More...

#include <PyDBObj.h>

Inheritance diagram for PyDBObj:

Collaboration diagram for PyDBObj:

Public Member Functions
	PyDBObj (const std::string &name, bool required=true)
	Construct the object from the name of the payload.
	PyDBObj (const TClass *objClass, bool required=true)
	Construct the object from the type of the payload, payload name will be the class name.
	PyDBObj (const std::string &name, const TClass *objClass, bool required=true)
	Construct the object from the name of the payload and make sure the class if compatible with objClass.
const TObject *	_obj () const
	Return the object.
PyObject *	getIntraRunBoundariesList () const
	Get the intra-run boundaries, if any, as a python list.
bool	isValid () const
	Check whether a valid object was obtained from the database.
bool	hasChanged ()
	Check whether the object has changed since the last call to hasChanged of the accessor).

Private Member Functions
const std::string &	getName () const
	Return name under which the object is saved in the DBStore.
	operator bool () const
	Imitate pointer functionality.
virtual bool	operator== (const DBAccessorBase &other) const
	Check if two store accessors point to the same object/array.
virtual bool	operator!= (const DBAccessorBase &other) const
	Check if two store accessors point to a different object/array.
void	addCallback (std::function< void(const std::string &)> callback, bool onDestruction=false)
	Add a callback method.
void	addCallback (std::function< void()> callback, bool onDestruction=false)
	Add a callback method.
template<class T >
void	addCallback (T *object, void(T::*callback)())
	Add a callback method of an object.
const std::string &	getGlobaltag () const
	Return the globaltag name (or testing payloads path) this object is loaded from.
unsigned int	getRevision () const
	Return current revision of the object.
IntervalOfValidity	getIoV () const
	Return current IoV of the object.
const std::string &	getChecksum () const
	Get current checksum.
const std::string &	getFilename () const
	Get the filename this object is loaded from.
bool	isIntraRunDependent () const
	Check wether this conditions object has some intra-run dependencies.
const std::vector< unsigned int >	getIntraRunBoundaries () const
	Get the intra-run boundaries, if any.
bool	isRequired () const
	Check whether this conditions object is required (at least one user declared it as required)
template<class T = TObject>
const T *	getObject () const
	Return a pointer to the Object already cast to the correct type.
bool	ensureAttached () const
	Make sure we are attached to the the DBStore.
void	storeEntryChanged (bool destructed)
	Callback function which gets called by the DBStoreEntry object if it changes.

Private Attributes
const DBStoreEntry::EPayloadType	m_type
	Type of the payload.
const std::string	m_name
	Name of the payload in the database.
const TClass *	m_objClass
	Class of the payload if type is c_Object.
const bool	m_isArray
	True if the payload is an array of objects.
const bool	m_isRequired
	True if the payload is required, otherwise no errors will be raised if it cannot be found.
DBStoreEntry *	m_entry
	Pointer to the entry in the DBStore.
bool	m_changed {false}
	Internal flag whether the object has changed since we last checked.
std::vector< std::pair< std::function< void(const std::string &)>, bool > >	m_callbacks
	List of all registered callback functions.

Detailed Description

Class to access a DBObjPtr from Python.

In contrast to the C++ DBObjPtr we don't have templates but python will handle the typing dynamically.

from ROOT import Belle2
beamparams = Belle2.PyDBObj('BeamParameters')
# alternative: beamparams = Belle2.PyDBObj(Belle2.BeamParameters.Class())
# Or with name and type: beamparams = Belle2.PyDBObj("BeamParameters", Belle2.BeamParameters.Class())
print(beamparams.getMass(), beamparams.getEnergy())
# alternative: beamparams.obj().getMass()

Most of the time you can just use the PyDBObj instance like an constant instance of the class it represents, i.e. call all the members. The only exceptions are if the class has members which are also present in PyDBObj (for example isValid() or hasChanged()). In this case you need to use the obj() member to obtain a reference to the real object first as shown in the example.

Warning

Be aware that PyDBObj objects are only usable during event flow, that is in the initialize() or event() calls of a module as there is no Conditions data available otherwise.

See also

the array version PyDBArray as well as the interface classes to the DataStore, PyStoreArray and PyStoreObj

Definition at line 50 of file PyDBObj.h.

Constructor & Destructor Documentation

PyDBObj() [1/3]

PyDBObj ( const std::string &  name, bool  required = true  )

explicit

Construct the object from the name of the payload.

Definition at line 32 of file PyDBObj.cc.

: PyDBObj(name, getDefaultClass(name), required) {}

PyDBObj() [2/3]

PyDBObj ( const TClass *  objClass, bool  required = true  )

explicit

Construct the object from the type of the payload, payload name will be the class name.

Definition at line 34 of file PyDBObj.cc.

: PyDBObj(DataStore::defaultObjectName(objClass), objClass, required) {}

PyDBObj() [3/3]

PyDBObj ( const std::string &  name, const TClass *  objClass, bool  required = true  )

explicit

Construct the object from the name of the payload and make sure the class if compatible with objClass.

Definition at line 36 of file PyDBObj.cc.

: DBAccessorBase(name, objClass, false, required) {}

Member Function Documentation

_obj()

const TObject * _obj ( ) const

inline

Return the object.

Sadly the const in the return value is lost in python so this is a protected method and we add a pure python method to wrap the object in something to guarantee constness in framework/scripts/basf2.py

Definition at line 70 of file PyDBObj.h.

{ return isValid() ? getObject() : nullptr; }

addCallback() [1/3]

void addCallback ( std::function< void()>  callback, bool  onDestruction = false  )

inlineinherited

Add a callback method.

The given method will be called whenever there is a new database entry for this DBAccessor.

Parameters

callback	function pointer to a callback function
onDestruction	if true the callback will not be called for each change but only when the Database entry is deleted and can be used to remove dangling pointers to the entry.

Definition at line 118 of file DBAccessorBase.h.

    {
      addCallback([callback](const std::string&) -> void { callback(); }, onDestruction);
    }

addCallback() [2/3]

void addCallback ( std::function< void(const std::string &)>  callback, bool  onDestruction = false  )

inlineinherited

Add a callback method.

The given method will be called whenever there is a new database entry for this DBAccessor. The one parameter is the name of the DB entry which changed (in case the same callback method is to be used for multiple payloads.

Parameters

callback	function pointer to a callback function
onDestruction	if true the callback will not be called for each change but only when the Database entry is deleted and can be used to remove dangling pointers to the entry.

Definition at line 105 of file DBAccessorBase.h.

    {
      m_callbacks.emplace_back(callback, onDestruction);
    }

addCallback() [3/3]

void addCallback ( T *  object, void(T::*)()  callback  )

inlineinherited

Add a callback method of an object.

The given method will be called whenever there is a new database entry for this DBAccessor.

Parameters

object	The object with the callback method.
callback	The callback method.

Definition at line 130 of file DBAccessorBase.h.

    {
      addCallback([ = ](const std::string&) {(*object.*callback)();});
    }

ensureAttached()

bool ensureAttached ( ) const

inlineprotectedinherited

Make sure we are attached to the the DBStore.

If not try to reconnect

Definition at line 171 of file DBAccessorBase.h.

    {
      if (!m_entry) {
        B2DEBUG(32, "DBAccessor " << m_name << " lost connection, reattaching");
        m_entry = DBStore::Instance().getEntry(m_type, m_name, m_objClass, m_isArray, m_isRequired);
        m_changed = true;
        if (!m_entry) return false;
        m_entry->registerAccessor(const_cast<DBAccessorBase*>(this));
      }
      return true;
    }

getChecksum()

const std::string & getChecksum ( ) const

inlineinherited

Get current checksum.

Definition at line 145 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getChecksum(); }

getFilename()

const std::string & getFilename ( ) const

inlineinherited

Get the filename this object is loaded from.

Definition at line 148 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getFilename(); }

getGlobaltag()

const std::string & getGlobaltag ( ) const

inlineinherited

Return the globaltag name (or testing payloads path) this object is loaded from.

Definition at line 136 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getGlobaltag(); }

getIntraRunBoundaries()

const std::vector< unsigned int > getIntraRunBoundaries ( ) const

inlineinherited

Get the intra-run boundaries, if any.

If the intra-run dependency is by event number, the event numbers used as boundaries are returned.

Definition at line 157 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getIntraRunBoundaries(); }

getIntraRunBoundariesList()

PyObject * getIntraRunBoundariesList

(

)

const

Get the intra-run boundaries, if any, as a python list.

Definition at line 38 of file PyDBObj.cc.

{
  PyObject* list = PyList_New(0);
  // Currently, the boundaries are defined only as unsigned int.
  // If in the future this will change, this method has to be updated accordingly.
  for (auto boundary : getIntraRunBoundaries())
    PyList_Append(list, PyLong_FromUnsignedLong(boundary));
  return list;
}

getIoV()

IntervalOfValidity getIoV ( ) const

inlineinherited

Return current IoV of the object.

Definition at line 142 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getIoV(); }

getName()

const std::string & getName ( ) const

inlineinherited

Return name under which the object is saved in the DBStore.

Definition at line 66 of file DBAccessorBase.h.

{ return m_name; }

getObject()

const T * getObject ( ) const

inlineprotectedinherited

Return a pointer to the Object already cast to the correct type.

Definition at line 164 of file DBAccessorBase.h.

    {
      if (!ensureAttached()) return nullptr;
      return reinterpret_cast<const T*>(m_entry->getObject());
    }

getRevision()

unsigned int getRevision ( ) const

inlineinherited

Return current revision of the object.

Definition at line 139 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->getRevision(); }

hasChanged()

bool hasChanged ( )

inline

Check whether the object has changed since the last call to hasChanged of the accessor).

Definition at line 89 of file DBAccessorBase.h.

    {
      const bool ret = m_changed;
      m_changed = false;
      return ret;
    }

isIntraRunDependent()

bool isIntraRunDependent ( ) const

inlineinherited

Check wether this conditions object has some intra-run dependencies.

Definition at line 151 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->isIntraRunDependent(); }

isRequired()

bool isRequired ( ) const

inlineinherited

Check whether this conditions object is required (at least one user declared it as required)

Definition at line 160 of file DBAccessorBase.h.

{ ensureAttached(); return m_entry->isRequired(); }

isValid()

bool isValid ( ) const

inline

Check whether a valid object was obtained from the database.

Returns

True if the object exists.

Definition at line 72 of file DBAccessorBase.h.

{if (!ensureAttached()) return false; return (m_entry->getObject() != nullptr);}

operator bool()

operator bool ( ) const

inlineinherited

Imitate pointer functionality.

Definition at line 74 of file DBAccessorBase.h.

operator!=()

virtual bool operator!= ( const DBAccessorBase &  other ) const

inlinevirtualinherited

Check if two store accessors point to a different object/array.

Definition at line 83 of file DBAccessorBase.h.

    {
      return !(*this == other);
    }

operator==()

virtual bool operator== ( const DBAccessorBase &  other ) const

inlinevirtualinherited

Check if two store accessors point to the same object/array.

Definition at line 77 of file DBAccessorBase.h.

    {
      return getName() == other.getName();
    }

storeEntryChanged()

void storeEntryChanged ( bool  destructed )

inlineprotectedinherited

Callback function which gets called by the DBStoreEntry object if it changes.

Definition at line 184 of file DBAccessorBase.h.

    {
      // we obviously changed
      m_changed = true;
      // StoreEntry is destructed, remove reference
      if (destructed) m_entry = nullptr;
      // Now run all registered callbacks
      // TODO: We could guard m_callbacks against insertions during callback
      // execution to prevent exponential growth of callbacks
      for (const auto& cb : m_callbacks) {
        if (destructed == cb.second) cb.first(m_name);
      }
    }

Member Data Documentation

m_callbacks

std::vector<std::pair<std::function<void(const std::string&)>, bool> > m_callbacks

protectedinherited

List of all registered callback functions.

Definition at line 213 of file DBAccessorBase.h.

m_changed

bool m_changed {false}

mutableprotectedinherited

Internal flag whether the object has changed since we last checked.

Definition at line 211 of file DBAccessorBase.h.

m_entry

DBStoreEntry* m_entry

mutableprotectedinherited

Pointer to the entry in the DBStore.

Definition at line 209 of file DBAccessorBase.h.

m_isArray

const bool m_isArray

protectedinherited

True if the payload is an array of objects.

Definition at line 205 of file DBAccessorBase.h.

m_isRequired

const bool m_isRequired

protectedinherited

True if the payload is required, otherwise no errors will be raised if it cannot be found.

Definition at line 207 of file DBAccessorBase.h.

m_name

const std::string m_name

protectedinherited

Name of the payload in the database.

Definition at line 201 of file DBAccessorBase.h.

m_objClass

const TClass* m_objClass

protectedinherited

Class of the payload if type is c_Object.

Definition at line 203 of file DBAccessorBase.h.

m_type

const DBStoreEntry::EPayloadType m_type

protectedinherited

Type of the payload.

Definition at line 199 of file DBAccessorBase.h.

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The documentation for this class was generated from the following files:

• framework/pybasf2/include/PyDBObj.h
• framework/pybasf2/src/PyDBObj.cc