path: root/TAO/examples/Load_Balancing/Load_Balancer_i.cpp

// $Id$
// ============================================================================
//
// = FILENAME
//   Load_Balancer_i.cpp
//
// = AUTHOR
//    Marina Spivak <marina@cs.wustl.edu>
//
// ============================================================================

#include "Load_Balancer_i.h"
#include "ace/Auto_Ptr.h"

Object_Group_Factory_i::Object_Group_Factory_i (void)
{
}

Object_Group_Factory_i::~Object_Group_Factory_i (void)
{
}

Load_Balancer::Object_Group_ptr
Object_Group_Factory_i::make_round_robin (const char * id,
                                          CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException,
                     Load_Balancer::duplicate_group))
{
  return make_group (0,
                     id,
                     ACE_TRY_ENV);
}

Load_Balancer::Object_Group_ptr
Object_Group_Factory_i::make_random (const char * id,
                                     CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException,
                     Load_Balancer::duplicate_group))
{
  return make_group (1,
                     id,
                     ACE_TRY_ENV);
}

Load_Balancer::Object_Group_ptr
Object_Group_Factory_i::make_group (int random,
                                    const char * id,
                                    CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException,
                     Load_Balancer::duplicate_group))
{
  ACE_CString group_id (id);

  // Check to make sure we don't already have a group with the same
  // <id>.
  if (rr_groups_.find (group_id) == 0
      || random_groups_.find (group_id) == 0)
    ACE_THROW_RETURN (Load_Balancer::duplicate_group (),
                      Load_Balancer::Object_Group::_nil ());
  else
    {
      // Store our result here for return.
      Load_Balancer::Object_Group_var group;

      // Create an appropriate servant.
      Object_Group_i * group_servant;
      if (random)
        ACE_NEW_THROW_EX (group_servant,
                          Random_Object_Group (id),
                          CORBA::NO_MEMORY ());
      else
        ACE_NEW_THROW_EX (group_servant,
                          RR_Object_Group (id),
                          CORBA::NO_MEMORY ());
      ACE_CHECK_RETURN (group._retn ());

      // Temporarily put the servant into the auto_ptr.
      ACE_Auto_Basic_Ptr<Object_Group_i> temp (group_servant);

      // Register with the poa, begin using ref. counting.
      group = group_servant->_this (ACE_TRY_ENV);
      ACE_CHECK_RETURN (group._retn ());

      group_servant->_remove_ref (ACE_TRY_ENV);
      ACE_CHECK_RETURN (Load_Balancer::Object_Group::_nil ());
      temp.release ();

      // Make an entry in appropriate map of groups.
      if (random)
        {
          if (random_groups_.bind (group_id, group) == -1)
            ACE_THROW_RETURN (CORBA::INTERNAL (),
                              Load_Balancer::Object_Group::_nil ());
        }
      else
        if (rr_groups_.bind (group_id, group) == -1)
          ACE_THROW_RETURN (CORBA::INTERNAL (),
                            Load_Balancer::Object_Group::_nil ());
      // Return.
      ACE_DEBUG ((LM_DEBUG, "Successfully created new group: %s\n", id));
      return group._retn ();
    }
}

Load_Balancer::Object_Group_ptr
Object_Group_Factory_i::resolve (const char * id,
                                 CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException,
                     Load_Balancer::no_such_group))
{
  ACE_CString group_id (id);
  Load_Balancer::Object_Group_var group;

  if (rr_groups_.find (group_id, group) == -1
      && random_groups_.find (group_id, group) == -1)
    ACE_THROW_RETURN (Load_Balancer::no_such_group (),
                      Load_Balancer::Object_Group::_nil ());
  else
    return group._retn ();
}

Load_Balancer::Group_List *
Object_Group_Factory_i::list_groups (int random,
                                     CORBA::Environment &ACE_TRY_ENV)
{
  Load_Balancer::Group_List * list;

  // Figure out the length of the list.
  CORBA::ULong len;
  if (random)
    len = random_groups_.current_size ();
  else
    len = rr_groups_.current_size ();

  // Allocate the list of <len> length.
  ACE_NEW_THROW_EX (list,
                    Load_Balancer::Group_List (len),
                    CORBA::NO_MEMORY ());
  ACE_CHECK_RETURN (list);
  list->length (len);

  // Create an iterator for group structure to populate the list.
  Object_Group_Factory_i::HASH_MAP::ITERATOR *group_iter;
  Object_Group_Factory_i::HASH_MAP::ITERATOR random_iter (random_groups_);
  Object_Group_Factory_i::HASH_MAP::ITERATOR rr_iter (rr_groups_);
  if (random)
    group_iter = &random_iter;
  else
    group_iter = &rr_iter;

  // Iterate over groups and populate the list.
  Object_Group_Factory_i::HASH_MAP::ENTRY *hash_entry;
  for (CORBA::ULong i = 0; i < len; i++)
    {
      group_iter->next (hash_entry);
      group_iter->advance ();

      (*list)[i] = hash_entry->ext_id_.c_str ();
    }

  return list;
}

Load_Balancer::Group_List *
Object_Group_Factory_i::round_robin_groups (CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException))
{
  return list_groups (0, ACE_TRY_ENV);
}

Load_Balancer::Group_List *
Object_Group_Factory_i::random_groups (CORBA::Environment &ACE_TRY_ENV)
    ACE_THROW_SPEC ((CORBA::SystemException))
{
  return list_groups (1, ACE_TRY_ENV);
}

Object_Group_i::Object_Group_i (const char * id)
  : id_ (id)
{
}

Object_Group_i::~Object_Group_i (void)
{
  // Need to delete all the items from the member_id_list, to avoid
  // memory leaks.
  Object_Group_i::ITERATOR iter (member_id_list_);

  do
    {
      delete (iter.next ());
    } while (iter.advance ());
}

char *
Object_Group_i::id (CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException))
{
  ACE_UNUSED_ARG (ACE_TRY_ENV);
  return CORBA::string_dup (id_.c_str ());
}

void
Object_Group_i::bind (const Load_Balancer::Member & member,
                      CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::duplicate_member))
{
  ACE_CString member_id (member.id);
  CORBA::Object_var obj = CORBA::Object::_duplicate (member.obj.in ());

  // Insert new member into <members_> and check for duplicates/failures.
  int result = members_.trybind (member_id, obj);
  if (result == 1)
    ACE_THROW (Load_Balancer::duplicate_member ());
  else if (result == -1)
    ACE_THROW (CORBA::INTERNAL ());

  // Insert new member's id into <member_id_list_>.
  ACE_CString *new_id;
  ACE_NEW_THROW_EX (new_id,
                    ACE_CString (member.id),
                    CORBA::NO_MEMORY ());
  ACE_CHECK;
  if (member_id_list_.insert_tail (new_id) == 0)
    ACE_THROW (CORBA::NO_MEMORY ());

  // Theoretically, we should deal with memory failures more
  // thoroughly.  But, practically, the whole system is going to be
  // hosed anyways ...
}

void
Object_Group_i::unbind (const char * id,
                        CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::no_such_member))
{
  ACE_CString member_id (id);

  // Code below works iff list and hash map states are consistent,
  // which is the case unless the system experienced major problems,
  // e.g., ran out of memory ...

  // Check to make sure we have it.
  if (members_.find (member_id) == -1)
    ACE_THROW (Load_Balancer::no_such_member ());

  // Remove all entries for this member.
  members_.unbind (member_id);

  Object_Group_i::ITERATOR iter (member_id_list_);
  while (member_id != *(iter.next ()))
    iter.advance ();
  delete (iter.next ());
  iter.remove ();
}

CORBA::Object_ptr
Object_Group_i::resolve_with_id (const char * id,
                                 CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::no_such_member))
{
  CORBA::Object_var obj;
  ACE_CString member_id (id);

  if (members_.find (member_id, obj) == -1)
    ACE_THROW_RETURN (Load_Balancer::no_such_member (),
                      obj._retn ());

  return obj._retn ();
}

Load_Balancer::Member_ID_List *
Object_Group_i::members (CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException))
{
  Load_Balancer::Member_ID_List * list;

  // Figure out the length of the list.
  CORBA::ULong len = members_.current_size ();

  // Allocate the list of <len> length.
  ACE_NEW_THROW_EX (list,
                    Load_Balancer::Member_ID_List (len),
                    CORBA::NO_MEMORY ());
  ACE_CHECK_RETURN (list);
  list->length (len);

  // Create an iterator for <member_id_list_> to populate the list.
  Object_Group_i::ITERATOR id_iter (member_id_list_);

  // Iterate over groups and populate the list.
  for (CORBA::ULong i = 0; i < len; i++)
    {
      (*list)[i] = id_iter.next ()->c_str ();
      id_iter.advance ();
    }

  return list;
}

void
Object_Group_i::destroy (CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException))
{
  // Deregister with POA.
  PortableServer::POA_var poa =
    this->_default_POA (ACE_TRY_ENV);
  ACE_CHECK;

  PortableServer::ObjectId_var id =
    poa->servant_to_id (this,
                        ACE_TRY_ENV);
  ACE_CHECK;

  poa->deactivate_object (id.in (),
                          ACE_TRY_ENV);
  ACE_CHECK;
}

Random_Object_Group::Random_Object_Group (const char *id)
  : Object_Group_i (id)
{
  // Seed the random number generator.
  ACE_OS::srand (ACE_OS::time ());
}

CORBA::Object_ptr
Random_Object_Group::resolve (CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::no_such_member))
{
  CORBA::Object_var obj;

  size_t group_size = members_.current_size ();
  if (group_size == 0)
    ACE_THROW_RETURN (Load_Balancer::no_such_member (),
                      obj._retn ());

  // Generate random number in the range [0, group_size - 1]
  size_t member = ACE_OS::rand() % group_size;

  // Get the id of the member to return to the client.
  ACE_CString *id;
  member_id_list_.get (id, member);
  ACE_DEBUG ((LM_DEBUG, "In Random Group resolved to: %s\n",
              id->c_str()));

  // Return the object reference corresponding to the found id to the client.
  members_.find (*id, obj);
  return obj._retn ();
}

RR_Object_Group::RR_Object_Group (const char *id)
  : Object_Group_i (id),
    next_ (0)
{
}

CORBA::Object_ptr
RR_Object_Group::resolve (CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::no_such_member))
{
  CORBA::Object_var obj;

  size_t group_size = members_.current_size ();
  if (group_size == 0)
    ACE_THROW_RETURN (Load_Balancer::no_such_member (),
                      obj._retn ());

  // Get the id of the member to return to the client.
  ACE_CString *id;
  member_id_list_.get (id, next_);
  ACE_DEBUG ((LM_DEBUG, "In RR Group resolved to: %s\n", id->c_str ()));

  // Adjust <next_> for the next invocation.
  next_ = (next_ + 1) % group_size;

  // Return the object reference corresponding to the found id to the client.
  if (members_.find (*id, obj) == -1)
    ACE_THROW_RETURN (CORBA::INTERNAL (),
                      CORBA::Object::_nil ());

   return obj._retn ();
}

void
RR_Object_Group::unbind (const char *id,
                         CORBA::Environment &ACE_TRY_ENV)
  ACE_THROW_SPEC ((CORBA::SystemException,
                   Load_Balancer::no_such_member))
{
  ACE_CString member_id (id);

  // Check to make sure we have it.
  if (members_.find (member_id) == -1)
    ACE_THROW (Load_Balancer::no_such_member ());

  // Remove all entries for this member.
  members_.unbind (member_id);

  // As we remove the id from the <member_id_list>, we note the
  // position of the id in the list.
  size_t position = 0;
  Object_Group_i::ITERATOR iter (member_id_list_);
  while (member_id != *(iter.next ()))
    {
      iter.advance ();
      position++;
    }
  delete (iter.next ());
  iter.remove ();

  // Update <next_> if necessary to reflect the deletion.
  if (position < next_)
    next_--;

  else if (position == next_)
    next_ = next_ % (members_.current_size ());
}

#if defined (ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION)
template class ACE_Hash_Map_Iterator_Base_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Iterator<ACE_CString, Load_Balancer::Object_Group_var, ACE_Null_Mutex>;
template class ACE_Hash_Map_Iterator_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Reverse_Iterator_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Reverse_Iterator_Ex<ACE_CString, CORBA_Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Manager_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Manager<ACE_CString, Load_Balancer::Object_Group_var, ACE_Null_Mutex>;
template class ACE_Hash<ACE_CString>;
template class ACE_Equal_To<ACE_CString>;
template class ACE_Hash_Map_Entry<ACE_CString, Load_Balancer::Object_Group_var>;

template class ACE_Hash_Map_Iterator_Base_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Iterator<ACE_CString, CORBA::Object_var, ACE_Null_Mutex>;
template class ACE_Hash_Map_Iterator_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Manager_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>;
template class ACE_Hash_Map_Manager<ACE_CString, CORBA::Object_var, ACE_Null_Mutex>;
template class ACE_Hash_Map_Entry<ACE_CString, CORBA::Object_var>;

template class ACE_DLList<ACE_CString>;
template class ACE_DLList_Iterator<ACE_CString>;

template class ACE_Auto_Basic_Ptr<Object_Group_i>;

#elif defined (ACE_HAS_TEMPLATE_INSTANTIATION_PRAGMA)
#pragma instantiate  ACE_Hash_Map_Iterator_Base_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Iterator<ACE_CString, Load_Balancer::Object_Group_var, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Iterator_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Reverse_Iterator_Ex<ACE_CString,Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Reverse_Iterator_Ex<ACE_CString, CORBA_Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Manager_Ex<ACE_CString, Load_Balancer::Object_Group_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Manager<ACE_CString, Load_Balancer::Object_Group_var, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash<ACE_CString>
#pragma instantiate  ACE_Equal_To<ACE_CString>
#pragma instantiate  ACE_Hash_Map_Entry<ACE_CString, Load_Balancer::Object_Group_var>

#pragma instantiate  ACE_Hash_Map_Iterator_Base_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Iterator<ACE_CString, CORBA::Object_var, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Iterator_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Manager_Ex<ACE_CString, CORBA::Object_var, ACE_Hash<ACE_CString>, ACE_Equal_To<ACE_CString>, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Manager<ACE_CString, CORBA::Object_var, ACE_Null_Mutex>
#pragma instantiate  ACE_Hash_Map_Entry<ACE_CString, CORBA::Object_var>

#pragma instantiate  ACE_DLList<ACE_CString>
#pragma instantiate  ACE_DLList_Iterator<ACE_CString>

#pragma instantiate  ACE_Auto_Basic_Ptr<Object_Group_i>

#endif /* ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION */