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// -*- C++ -*-
#include "LB_Minimum_Dispersion.h"
#include "LB_Location_Map.h"
#include "LB_ObjectGroup_Map.h"
//#include "ReplicaProxy.h"
ACE_RCSID (LoadBalancing,
LB_Minimum_Dispersion,
"$Id$")
TAO_LB_Minimum_Dispersion_Strategy::TAO_LB_Minimum_Dispersion_Strategy (void)
{
}
TAO_LB_Minimum_Dispersion_Strategy::~TAO_LB_Minimum_Dispersion_Strategy (void)
{
}
CORBA::Object_ptr
TAO_LB_Minimum_Dispersion_Strategy::replica (
TAO_LB_ObjectGroup_Map_Entry *entry,
CORBA::Environment &ACE_TRY_ENV)
ACE_THROW_SPEC ((CORBA::SystemException))
{
for ( ; ; )
{
ACE_GUARD_RETURN (TAO_SYNCH_MUTEX,
guard,
entry->lock,
CORBA::Object::_nil ());
if (entry->replica_infos.is_empty ())
// @@ What do we do if the set is empty?
ACE_THROW_RETURN (CORBA::OBJECT_NOT_EXIST (),
CORBA::Object::_nil ());
TAO_LB_ReplicaInfo_Set::iterator begin = entry->replica_infos.begin ();
TAO_LB_ReplicaInfo_Set::iterator end = entry->replica_infos.end ();
TAO_LB_ReplicaInfo_Set::iterator i = begin;
TAO_LB_ReplicaInfo *replica_info = (*i);
LoadBalancing::LoadList *d =
replica_info->location_entry->load_list.ptr ();
for (++i ; i != end; ++i)
{
LoadBalancing::LoadList *load =
(*i)->location_entry->load_list.ptr ();
// @@ Hardcode one load and don't bother checking the
// LoadId, for now. (just to get things going)
if ((*d)[CORBA::ULong (0)].value > (*load)[CORBA::ULong (0)].value)
{
replica_info = *i;
d = (*i)->location_entry->load_list.ptr ();
}
}
// Before returning an object reference to the client
// validate it first.
CORBA::Object_ptr object = replica_info->replica.in ();
{
ACE_Reverse_Lock<TAO_SYNCH_MUTEX> reverse_lock (entry->lock);
ACE_GUARD_RETURN (ACE_Reverse_Lock<TAO_SYNCH_MUTEX>,
reverse_guard,
reverse_lock,
CORBA::Object::_nil ());
// @@ Ossama: we should setup a timeout policy here...
ACE_TRY
{
CORBA::Boolean non_existent =
object->_non_existent (ACE_TRY_ENV);
ACE_TRY_CHECK;
if (!non_existent)
{
return CORBA::Object::_duplicate (object);
}
}
ACE_CATCHANY
{
// @@ HACK! Do the right thing!
return CORBA::Object::_duplicate (object);
}
ACE_ENDTRY;
}
}
}
void
TAO_LB_Minimum_Dispersion_Strategy::analyze_loads (
TAO_LB_Location_Map &location_map,
CORBA::Environment &ACE_TRY_ENV)
{
int send_load_advisory = 0;
{
ACE_MT (ACE_GUARD (TAO_SYNCH_MUTEX,
guard,
this->lock_));
TAO_LB_Location_Map::iterator begin =
location_map.begin ();
TAO_LB_Location_Map::iterator end =
location_map.end ();
float s = 0;
CORBA::ULong n = 0;
TAO_LB_Location_Map::iterator i = begin;
for ( ; i != end; ++i)
{
s += (*i)->int_id_.load_list[0].value; // @@ Hard coded to
// get things
// going.
n++;
}
float avg = (n == 0 ? s : s / n);
float cl = proxy->current_load ();
if (avg == 0)
return;
float relative_load = cl / avg;
// @@ Ossama: Make the 1.5 factor adjustable, it is how much
// dispersion we tolerate before starting to send advisories.
if (relative_load > 1 + 1.5F / n)
{
proxy->has_high_load_ = 1;
send_load_advisory = 2; // 2 == Send high load advisory
}
if (send_load_advisory == 1 && relative_load < 1 + 0.9F / n)
{
proxy->has_high_load_ = 0;
send_load_advisory = 1; // 1 == Send nominal load advisory
}
}
// @@ Ossama: no debug messages in production code, my fault....
// ACE_DEBUG ((LM_DEBUG, "Load[%x] %f %f %f\n",
// proxy, cl, avg, relative_load));
// @@ Ossama: Make the 1.5 factor adjustable, it is how much
// dispersion we tolerate before starting to send advisories.
if (send_load_advisory == 2)
{
proxy->control_->high_load_advisory (ACE_TRY_ENV);
ACE_CHECK;
return; // We may not throw an exception, so explicitly return.
}
// @@ Ossama: notice that we wait until the load is signifcantly
// lower before sending the nominal load advisory, it does not
// matter that much because the replicas automatically restart after
// rejecting one client....
// @@ Ossama: make the 0.9 factor adjustable, at least at
// construction time...
if (send_load_advisory == 1)
{
proxy->control_->nominal_load_advisory (ACE_TRY_ENV);
ACE_CHECK;
}
}
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