StoreGate/StoreGate/WriteHandle.icc

Go to the documentation of this file.

/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
/**
 * @file StoreGate/WriteHandle.icc
 * @author S. Binet, P. Calafiura, scott snyder <snyder@bnl.gov>
 * @date Updated: Feb, 2016
 * @brief Handle class for recording to StoreGate.
 */
 
#ifndef STOREGATE_SG_WRITEHANDLE_ICC
#define STOREGATE_SG_WRITEHANDLE_ICC 1
 
 
#include "StoreGate/exceptions.h"
#include "AthenaKernel/ClassID_traits.h"
#include "AthenaKernel/errorcheck.h"
#include <stdexcept>
 
 
namespace SG {
 
 
//************************************************************************
// Constructors, etc.
//
 
 
/**
 * @brief Default constructor.
 *
 * The handle will not be usable until a non-blank key is assigned.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle()
  : VarHandleBase(ClassID_traits<T>::ID(), Gaudi::DataHandle::Writer)
{
}
 
 
/**
 * @brief Constructor specifying the key as a string.
 * @param sgkey StoreGate key of the referenced object.
 * @param storename Name of the referenced event store.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle (const std::string& sgkey,
                             const std::string& storename /* ="StoreGateSvc"*/)
  : VarHandleBase (ClassID_traits<T>::ID(), sgkey,
                   Gaudi::DataHandle::Writer, storename, nullptr)
{
}
 
 
/**
 * @brief Constructor specifying the key as a string, with context.
 * @param sgkey StoreGate key of the referenced object.
 * @param ctx The event context.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle(const std::string& sgkey,
                            const EventContext& ctx)
  : WriteHandle(sgkey, StoreID::storeName(StoreID::EVENT_STORE), ctx)
{
}
 
 
/**
 * @brief Constructor specifying the key as a string, with context.
 * @param sgkey StoreGate key of the referenced object.
 * @param storename Name of the referenced event store.
 * @param ctx The event context.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle(const std::string& sgkey,
                            const std::string& storename,
                            const EventContext& ctx)
  : VarHandleBase( ClassID_traits<T>::ID(),
                   sgkey, Gaudi::DataHandle::Writer, storename, &ctx )
{
}
 
 
/**
 * @brief Constructor from a WriteHandleKey.
 * @param key The key object holding the clid/key/store.
 *
 * This will raise an exception if the StoreGate key is blank,
 * or if the event store cannot be found.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle (const WriteHandleKey<T>& key)
  : VarHandleBase (key, nullptr)
{
}
 
 
/**
 * @brief Constructor from a WriteHandleKey and an explicit event context.
 * @param key The key object holding the clid/key.
 * @param ctx The event context.
 *
 * This will raise an exception if the StoreGate key is blank,
 * or if the event store cannot be found.
 *
 * If the default event store has been requested, then the thread-specific
 * store from the event context will be used.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle (const WriteHandleKey<T>& key,
                             const EventContext& ctx)
  : VarHandleBase (key, &ctx)
{
  // cppcheck-suppress missingReturn; false positive
}
 
 
/**
 * @brief Copy constructor.
 */
template <class T>
inline
WriteHandle<T>::WriteHandle(const WriteHandle& h)
  : VarHandleBase(h)
{
}
 
 
/**
 * @brief Move constructor.
 */
template <class T> 
WriteHandle<T>::WriteHandle(WriteHandle&& h)
  : VarHandleBase(std::move(h))
{
  m_lockAuxPending = h.m_lockAuxPending;
  h.m_lockAuxPending = nullptr;
}
 
 
/**
 * @brief Assignment operator.
 */
template <class T>
inline
WriteHandle<T>&
// m_lockAuxPending not copied --- want lifetime to stay with the
//  original WH.
// cppcheck-suppress operatorEqVarError
WriteHandle<T>::operator= (const WriteHandle& h)
{
  if (this != &h)
    this->VarHandleBase::operator=(h);
  return *this;
}
 
 
/**
 * @brief Move operator.
 */
template <class T>
inline
WriteHandle<T>& 
WriteHandle<T>::operator= (WriteHandle&& h)
{
  if (this != &h) {
    this->VarHandleBase::operator=(std::move(h));
    m_lockAuxPending = h.m_lockAuxPending;
    h.m_lockAuxPending = nullptr;
  }
  return *this;
}
 
 
/**
 * @brief Destructor.
 *
 * Lock an aux object if m_lockAuxPending is true.
 */
template <class T>
WriteHandle<T>::~WriteHandle()
{
  if (m_lockAuxPending) {
    m_lockAuxPending->setConst();
  }
}
 
 
//************************************************************************
// Deference.  These all return only the cached pointer.
//
 
 
/**
 * @brief Dereference the pointer.
 * Returns the cached pointer.  Throws ExcNullWriteHandle if null.
 */
template <class T>
inline
typename WriteHandle<T>::pointer_type
WriteHandle<T>::operator->()
{
  return WriteHandle<T>::checkedCachedPtr();
}
 
 
/**
 * @brief Dereference the pointer.
 * Returns the cached pointer.  Throws ExcNullWriteHandle if null.
 */
template <class T>
inline
typename WriteHandle<T>::reference_type
WriteHandle<T>::operator*()
{
  return *WriteHandle<T>::checkedCachedPtr();
}
 
 
/**
 * @brief Dereference the pointer.
 * Returns the cached pointer.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::cptr() const
{
  return reinterpret_cast<pointer_type>(this->m_ptr);
}
 
 
/**
 * @brief Dereference the pointer.
 * Returns the cached pointer.
 */
template <class T>
inline
typename WriteHandle<T>::pointer_type
WriteHandle<T>::ptr()
{
  return cachedPtr();
}
 
 
/**
 * @brief Return the cached pointer directly; no lookup.
 */
template <class T>
inline
typename WriteHandle<T>::pointer_type
WriteHandle<T>::cachedPtr()
{
  return reinterpret_cast<pointer_type>(this->m_ptr);
}
 
 
/**
 * @brief Can the handle be successfully dereferenced?
 */
template <class T>
inline
bool WriteHandle<T>::isValid()
{
  return this->m_ptr != nullptr;
}
 
 
//************************************************************************
// Record.
 
 
/**
 * @brief Record a const object to the store.
 * @param data The object to record.
 */
template <class T>
inline
StatusCode
WriteHandle<T>::WriteHandle::record (std::unique_ptr<T> data)
{
  return this->doRecord (std::move(data), true, false);
}
 
 
/**
 * @brief Record a non-const object to the store.
 * @param data The object to record.
 * @param isConst If true, record the object as const.
 */
template <class T>
inline
StatusCode
WriteHandle<T>::WriteHandle::recordNonConst (std::unique_ptr<T> data)
{
  return this->doRecord (std::move(data), false, false);
}
 
 
/**
 * @brief Record a const object and its auxiliary store to the store.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 */
template <class T>
template <class AUXSTORE>
inline
StatusCode
WriteHandle<T>::WriteHandle::record (std::unique_ptr<T> data,
                                     std::unique_ptr<AUXSTORE> auxstore)
{
  return record (std::move(data), std::move(auxstore), true);
}
 
 
/**
 * @brief Record a non-const object and its auxiliary store to the store.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 */
template <class T>
template <class AUXSTORE>
inline
StatusCode
WriteHandle<T>::WriteHandle::recordNonConst (std::unique_ptr<T> data,
                                             std::unique_ptr<AUXSTORE> auxstore)
{
  return record (std::move(data), std::move(auxstore), false);
}
 
 
/**
 * @brief Record a const shared DataObject to the store.
 * @param data The object to record.
 *
 * The event store takes shared ownership of the object.
 */
template <class T>
template <std::derived_from<DataObject> DOBJ>
requires std::convertible_to<DOBJ*, T*>
inline
StatusCode
WriteHandle<T>::record (SG::DataObjectSharedPtr<DOBJ> data)
{
  return this->doRecord (std::move(data), true, false);
}
 
 
/**
 * @brief Record a non-const shared DataObject to the store.
 * @param data The object to record.
 *
 * The event store takes shared ownership of the object.
 */
template <class T>
template <std::derived_from<DataObject> DOBJ>
requires std::convertible_to<DOBJ*, T*>
inline
StatusCode
WriteHandle<T>::recordNonConst (SG::DataObjectSharedPtr<DOBJ> data)
{
  return this->doRecord (std::move(data), false, false);
}
 
 
/**
 * @brief Record an object to the store.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (std::unique_ptr<T> data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  return doPut (nullptr, std::move(data), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (std::unique_ptr<const T> data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  return doPut (nullptr, std::move(data), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (std::unique_ptr<const ConstDataVector<T> > data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  std::unique_ptr<const T> coll (data.release()->asDataVector());
  return doPut (nullptr, std::move(coll), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     std::unique_ptr<const ConstDataVector<T> > data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  std::unique_ptr<const T> coll (data.release()->asDataVector());
  return doPut (&ctx, std::move(coll), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     std::unique_ptr<T> data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  return doPut (&ctx, std::move(data), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 * @param returnExisting Allow an existing object?
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     std::unique_ptr<const T> data,
                     bool returnExisting /*= false*/) const
{
  IProxyDict* store = nullptr;
  return doPut (&ctx, std::move(data), returnExisting, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param data The object to record.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 *
 * The event store takes shared ownership of the object.
 */
template <class T>
template <std::derived_from<DataObject> DOBJ>
requires std::convertible_to<DOBJ*, T*>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (SG::DataObjectSharedPtr<DOBJ> data) const
{
  IProxyDict* store = nullptr;
  return doPut (nullptr, std::move(data), false, store);
}
 
 
/**
 * @brief Record an object to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 *
 * The event store takes shared ownership of the object.
 */
template <class T>
template <std::derived_from<DataObject> DOBJ>
requires std::convertible_to<DOBJ*, T*>
inline
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     SG::DataObjectSharedPtr<DOBJ> data) const
{
  IProxyDict* store = nullptr;
  return doPut (&ctx, std::move(data), false, store);
}
 
 
/**
 * @brief Record an object and its auxiliary store to the store.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (std::unique_ptr<T> data,
                     std::unique_ptr<AUXSTORE> auxstore) const
{
  return doPut (nullptr, std::move(data), std::move(auxstore));
}
 
 
 
/**
 * @brief Record an object and its auxiliary store to the store.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 *
 * Unlike the version taking unique_ptr<T>, this does not alter the
 * store pointer of @c data.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (std::unique_ptr<const T> data,
                     std::unique_ptr<const AUXSTORE> auxstore) const
{
  return doPut (nullptr, std::move(data), std::move(auxstore));
}
 
 
/**
 * @brief Record an object and its auxiliary store to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     std::unique_ptr<T> data,
                     std::unique_ptr<AUXSTORE> auxstore) const
{
  return doPut (&ctx, std::move(data), std::move(auxstore));
}
 
 
/**
 * @brief Record an object and its auxiliary store to the store.
 * @param ctx The event context to use.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that one will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 *
 * Unlike the version taking unique_ptr<T>, this does not alter the
 * store pointer of @c data.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::put (const EventContext& ctx,
                     std::unique_ptr<const T> data,
                     std::unique_ptr<const AUXSTORE> auxstore) const
{
  return doPut (&ctx, std::move(data), std::move(auxstore));
}
 
 
/**
 * @brief Alternate notation for record.  Records a non-const object.
 * @param data Object to record.
 *
 * Throws an exception on failure.
 */
template <class T>
WriteHandle<T>& 
WriteHandle<T>::operator= (std::unique_ptr<T> data)
{
  if (recordNonConst (std::move(data)).isFailure()) {
    throw std::runtime_error ("WriteHandle<T>::operator=(unique_ptr) Record failed.");
  }
  return *this;
}
 
 
/**
 * @brief Make an alias.
 * @param key Alternate key by which the referenced object should be known.
 *
 * The current handle should be valid and referencing an object
 * (i.e., @c record should have been called on it).
 *
 * The object will also be known by the name given in @c key.
 */
template <class T>
StatusCode WriteHandle<T>::alias (const WriteHandleKey<T>& key)
{
  return symLink_impl (this->clid(), key.key());
}
 
 
/**
 * @brief Make an explicit link.
 * @param key Alternate clid by which the referenced object
 *            should be known.  The SG key must match the key of the
 *            current handle.
 *
 * You should generally not be using this!
 *
 * The current handle should be valid and referencing an object
 * (i.e., @c record should have been called on it).
 *
 * This makes a symlink: the object will be retrievable
 * as a different type.
 * 
 * Note that if @c T and @c @U are related via @c SG_BASE and/or
 * @c DATAVECTOR_BASE, then you shouldn't need to explicitly make a symlink;
 * that should happen automatically.
 *
 * If a @c U* is not convertable to a @c T* via C++ rules, then you likely
 * will be, at best, relying on undefined behavior.  You will probably
 * get warnings from the undefined behavior sanitizer when if you try
 * to dereference the @c U*.
 *
 * This usage is here mainly to assist in migrating some existing
 * patterns to MT.  You should think several times before using
 * in new code.
 */
template <class T>
template <class U>
StatusCode WriteHandle<T>::symLink (const WriteHandleKey<U>& other)
{
  if (this->key() != other.key()) {
    REPORT_ERROR (StatusCode::FAILURE)
      << "symLink: SG keys do not match: " << other.key() << " vs "
      << this->key();
    return StatusCode::FAILURE;
  }
  return symLink_impl (other.clid(), other.key());
}
 
 
/**
 * @brief Return the cached pointer directly.
 *
 * If it is null, throw ExcNullWriteHandle.
 */
template <class T>
typename WriteHandle<T>::pointer_type
WriteHandle<T>::checkedCachedPtr()
{
  if (!m_ptr)
    throwExcNullWriteHandle (clid(), key(), store());
  return cachedPtr();
}
 
 
/**
 * @brief Helper for record.
 * @param data The object to record.
 * @param isConst If true, record the object as const.
 * @param returnExisting Allow an existing object.
 */
template <class T>
template <class U>
StatusCode WriteHandle<T>::doRecord (U data,
                                     bool isConst,
                                     bool returnExisting)
{
  typedef typename U::element_type elt_t;
  
  // make sure the BaseInfo(Base) structure is initialized
  SG::BaseInfo<elt_t>::baseinfo();
 
  // If s_isConst is set for this type, then we want to automatically
  // make it const when recorded.
  bool allowMods = !isConst;
  if (ClassID_traits<elt_t>::s_isConst)
    allowMods = false;
 
  void* dataPtr(data.get());
  std::unique_ptr<DataObject> dobj (SG::asStorable (std::move (data)));
  return this->record_impl (std::move(dobj), dataPtr, allowMods, returnExisting);
}
 
 
/**
 * @brief Helper for put.
 * @param ctx The event context, or nullptr to use the current context.
 * @param data The object to record.
 * @param returnExisting Allow an existing object.
 * @param[out] store The store being used.
 *
 * Unlike record(), this does not change the handle object.
 * That means that will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, unless @c returnExisting is true, in which case
 * return success.  In either case, @c data is destroyed.
 */
template <class T>
template <class U>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::doPut (const EventContext* ctx,
                       U data,
                       bool returnExisting,
                       IProxyDict* & store) const
{
  //typedef typename U::element_type elt_t;
  typedef T elt_t;
  
  // make sure the BaseInfo(Base) structure is initialized
  SG::BaseInfo<elt_t>::baseinfo();
 
  const void* dataPtr = data.get();
  std::unique_ptr<DataObject> dobj (SG::asStorable (std::move (data)));
  return reinterpret_cast<const T*>
    (this->put_impl (ctx, std::move(dobj), dataPtr, false, returnExisting, store));
}
 
 
/**
 * @brief Helper for recording an object and its auxiliary store to the store.
 * @param ctx The event context, or nullptr to use the current context.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::doPut (const EventContext* ctx,
                       std::unique_ptr<T> data,
                       std::unique_ptr<AUXSTORE> auxstore) const
{
  T& dref = *data;
 
  // If there's no store association, do it now.
  if (data->getStore() == nullptr)
    data->setStore (auxstore.get());
 
  IProxyDict* store = nullptr;
  const T* ptr = this->doPut (ctx, std::move(data), false, store);
  if (!ptr) return nullptr;
 
  SG::DataObjectSharedPtr<DataObject> dobj
    (SG::asStorable (std::move (auxstore)));
  SG::DataProxy* proxy = store->recordObject (std::move(dobj),
                                              this->name() + "Aux.",
                                              false,
                                              false);
  if (!proxy) {
    REPORT_ERROR (StatusCode::FAILURE)
      << "recordObject of aux store failed";
 
    // If we've failed here, then the aux store object has been deleted,
    // but not the primary object.  Null out the store pointer to prevent
    // having a dangling pointer to a deleted object.
    dref.setStore (static_cast<SG::IConstAuxStore*>(nullptr));
    return nullptr;
  }
 
  return ptr;
}
 
 
/**
 * @brief Helper for recording an object and its auxiliary store to the store.
 * @param ctx The event context, or nullptr to use the current context.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 *
 * Unlike record(), this does not change the handle object.
 * That means that will not be able to get the object back
 * by dereferencing the handle.
 * Returns the object placed in the store, or nullptr if there
 * was an error.
 * If there was already an object in the store with the given key,
 * then return null, and the objects passed in are destroyed.
 */
template <class T>
template <class AUXSTORE>
typename WriteHandle<T>::const_pointer_type
WriteHandle<T>::doPut (const EventContext* ctx,
                       std::unique_ptr<const T> data,
                       std::unique_ptr<const AUXSTORE> auxstore) const
{
  IProxyDict* store = nullptr;
  const T* ptr = this->doPut (ctx, std::move(data), false, store);
  if (!ptr) return nullptr;
 
  SG::DataObjectSharedPtr<DataObject> dobj
    (SG::asStorable (std::move (auxstore)));
  SG::DataProxy* proxy = store->recordObject (std::move(dobj),
                                              this->name() + "Aux.",
                                              false,
                                              false);
  if (!proxy) {
    REPORT_ERROR (StatusCode::FAILURE)
      << "recordObject of aux store failed";
    return nullptr;
  }
 
  return ptr;
}
 
 
/**
 * @brief Record an object and its auxiliary store to the store.
 * @param data The object to record.
 * @param auxstore Auxiliary store object.
 * @param isConst If true, record the objects as const.
 */
template <class T>
template <class AUXSTORE>
StatusCode
WriteHandle<T>::record (std::unique_ptr<T> data,
                        std::unique_ptr<AUXSTORE> auxstore,
                        bool isConst)
{
  T& dref = *data;
 
  // If there's no store association, do it now.
  if (data->getStore() == nullptr)
    data->setStore (auxstore.get());
 
  if (isConst) {
    // Temporarily clear the store association, in order to prevent
    // the aux store from being locked at this point.
    IAuxStore* store = dref.getStore();
    if (store)
      dref.setStore (static_cast<SG::IAuxStore*>(nullptr));
    CHECK (this->record(std::move(data)));
    // Deliberately not using RAII here.  If there is an error,
    // then the object referenced by data will be deleted.
    dref.setStore (store);
  }
  else
    CHECK (this->recordNonConst(std::move(data)));
 
  // Store and proxy must be valid if we get to this point.
  
  SG::DataObjectSharedPtr<DataObject> dobj
    (SG::asStorable (std::move (auxstore)));
  SG::DataProxy* proxy = m_store->recordObject (std::move(dobj),
                                                this->name() + "Aux.",
                                                true,
                                                false);
  if (!proxy) {
    REPORT_ERROR (StatusCode::FAILURE)
      << "recordObject of aux store failed";
 
    // If we've failed here, then the aux store object has been deleted,
    // but not the primary object.  Null out the store pointer to prevent
    // having a dangling pointer to a deleted object.
    dref.setStore (static_cast<SG::IConstAuxStore*>(nullptr));
    return StatusCode::FAILURE;
  }
 
  if (m_proxy->isConst())
    m_lockAuxPending = proxy;
 
  return StatusCode::SUCCESS;
}
 
 
/**
 * @brief Return a @c WriteHandle referencing @c key.
 * @param key The key object holding the clid/key/store.
 *
 * This will raise an exception if the StoreGate key is blank,
 * or if the event store cannot be found.
 */
template <class T>
WriteHandle<T> makeHandle (const WriteHandleKey<T>& key)
{
  return WriteHandle<T> (key);
}
 
 
/**
 * @brief Return a @c WriteHandle referencing @c key for an explicit context.
 * @param key The key object holding the clid/key/store.
 * @param ctx The event context.
 *
 * This will raise an exception if the StoreGate key is blank,
 * or if the event store cannot be found.
 *
 * If the default event store has been requested, then the thread-specific
 * store from the event context will be used.
 */
template <class T>
WriteHandle<T> makeHandle (const WriteHandleKey<T>& key,
                           const EventContext& ctx)
{
  return WriteHandle<T> (key, ctx);
}
 
 
} /* namespace SG */
 
 
#endif //> !STOREGATE_SG_WRITEHANDLE_ICC