// $Id$

// ============================================================================
//
// = LIBRARY
//     TAO/examples/POA/Loader
//
// = FILENAME
//     Servant_Locator.cpp
//
// = DESCRIPTION
//     Implementation of ServantLocator_i class, used with a POA
//     having a NON_RETAIN policy.
//
// = AUTHOR
//     Kirthika Parameswaran <kirthika@cs.wustl.edu>
//
// ============================================================================

#include "Servant_Locator.h"

ACE_RCSID(Loader, Servant_Locator, "$Id$")

// Initialization.The dllname is used by the Loactor to load it into
// memory. The factory function is the point of entry into the dll and
// is used for obtaining the servant. The garbage_collection_function
// is used to kill the servant. 

ServantLocator_i::ServantLocator_i (CORBA::ORB_ptr orb,
                                    const char *dllname,
                                    const char *factory_function,
                                    const char *garbage_collection_function)
  : orb_ (CORBA::ORB::_duplicate (orb))
{
 // The dll is opened using the dllname passed.
   if (this->dll_.open (dllname) == -1)
     ACE_ERROR ((LM_ERROR,
                 "%p",
                 this->dll_.error ()));
                
  // Obtain the symbol for the function that will
  // get the servant object.
  servant_supplier_ = ACE_reinterpret_cast
    (SERVANT_FACTORY, this->dll_.symbol (factory_function));

  // Obtain tne symbol for the function which
  // will destroy the servant.  
  servant_garbage_collector_ = ACE_reinterpret_cast
    (SERVANT_GARBAGE_COLLECTOR, this->dll_.symbol (garbage_collection_function));

}

// This method associates an servant with the ObjectID.

PortableServer::Servant
ServantLocator_i::preinvoke (const PortableServer::ObjectId &oid,
                             PortableServer::POA_ptr poa,
                             const char * /* operation */,
                             PortableServer::ServantLocator::Cookie &cookie,
                             CORBA::Environment &ACE_TRY_ENV)
{
  PortableServer::Servant servant =
    (*servant_supplier_) (oid,
                          poa,
                          this->orb_.in ());
  if (servant != 0)
    {
      // Return the servant as the cookie , used as a check when
      // postinvoke is called on this ServantLocator_i.
      
      cookie = servant;
      return servant;
    }
  else
    ACE_THROW_RETURN (CORBA::OBJECT_NOT_EXIST (CORBA::COMPLETED_NO),
                      0);
}

// Since the servant gets invoked per operation, the servant has to be
// destroyed per operation too.  This is accomplished in the
// postinvoke method.

void
ServantLocator_i::postinvoke (const PortableServer::ObjectId &oid,
                              PortableServer::POA_ptr poa ,
                              const char * /* operation */,
                              PortableServer::ServantLocator::Cookie cookie,
                              PortableServer::Servant servant,
                              CORBA::Environment &/* env */)
{
  // Check the passed servant with the cookie.
  PortableServer::Servant my_servant =
    ACE_reinterpret_cast (PortableServer::Servant,
                          cookie);
  
  ACE_ASSERT (servant == my_servant);

  // Invoke the garbage_collection_function.
  (*servant_garbage_collector_) (oid,
                                 poa,
                                 servant);

  // To avoid warning about unused variable with ACE_NDEBUG.
  ACE_UNUSED_ARG (my_servant);
}