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// -*- C++ -*-
#include "LB_Random.h"
ACE_RCSID (LoadBalancing,
LB_Random,
"$Id$")
TAO_LB_Random::TAO_LB_Random (void)
{
// Seed the random number generator with the current time.
ACE_OS::srand (ACE_static_cast (unsigned int, ACE_OS::time ()));
}
char *
TAO_LB_Random::name (ACE_ENV_SINGLE_ARG_DECL_NOT_USED)
ACE_THROW_SPEC ((CORBA::SystemException))
{
return CORBA::string_dup ("Random");
}
CosLoadBalancing::Properties *
TAO_LB_Random::get_properties (ACE_ENV_SINGLE_ARG_DECL)
ACE_THROW_SPEC ((CORBA::SystemException))
{
CosLoadBalancing::Properties * props = 0;
ACE_NEW_THROW_EX (props,
CosLoadBalancing::Properties,
CORBA::NO_MEMORY (
CORBA::SystemException::_tao_minor_code (
TAO_DEFAULT_MINOR_CODE,
ENOMEM),
CORBA::COMPLETED_NO));
ACE_CHECK_RETURN (props);
return props;
}
void
TAO_LB_Random::push_loads (
const PortableGroup::Location & /* the_location */,
const CosLoadBalancing::LoadList & /* loads */
ACE_ENV_ARG_DECL)
ACE_THROW_SPEC ((CORBA::SystemException,
CosLoadBalancing::StrategyNotAdaptive))
{
ACE_THROW (CosLoadBalancing::StrategyNotAdaptive ());
}
CORBA::Object_ptr
TAO_LB_Random::next_member (
PortableGroup::ObjectGroup_ptr object_group,
CosLoadBalancing::LoadManager_ptr load_manager
ACE_ENV_ARG_DECL)
ACE_THROW_SPEC ((CORBA::SystemException,
PortableGroup::ObjectGroupNotFound,
PortableGroup::MemberNotFound))
{
PortableGroup::Locations_var locations =
load_manager->locations_of_members (object_group
ACE_ENV_ARG_PARAMETER);
ACE_CHECK_RETURN (CORBA::Object::_nil ());
const CORBA::ULong len = locations->length ();
if (len == 0)
ACE_THROW_RETURN (CORBA::TRANSIENT (),
CORBA::Object::_nil ());
// Pick a random location in the sequence using the higher order
// bits (zero based indexing).
//
// See Numerical Recipes in C: The Art of Scientific Computing
// (William H. Press, Brian P. Flannery, Saul A. Teukolsky,
// William T. Vetterling; New York: Cambridge University Press,
// 1992 (2nd ed., p. 277)) for details on why using the lower order
// bits, as in (rand() % 10), is bad. In particular, the lower
// order bits in older rand() implementations may not be as random
// as the higher order bits.
//
// @todo It would be better to use the random() function since it
// is supposed to have a larger period than rand(), in
// addition to the fact that the lower order bits should be as
// random as the higher order bits.
const CORBA::Float flen = len; // Prevent integer arithmetic
// overflow.
const CORBA::ULong i =
ACE_static_cast (CORBA::ULong,
flen * ACE_OS::rand () / (RAND_MAX + 1.0));
ACE_ASSERT (i < len);
// ACE_DEBUG ((LM_DEBUG,
// "** Len = %u\t"
// "Location # %u\t"
// "Loc Name = \"%s\"\n",
// len,
// i,
// locations[i][0].id.in ()));
return load_manager->get_member_ref (object_group,
locations[i]
ACE_ENV_ARG_PARAMETER);
}
void
TAO_LB_Random::analyze_loads (
PortableGroup::ObjectGroup_ptr /* object_group */,
CosLoadBalancing::LoadManager_ptr /* load_manager */
ACE_ENV_ARG_DECL_NOT_USED)
ACE_THROW_SPEC ((CORBA::SystemException))
{
}
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