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// -*- C++ -*-
// $Id$
#include "Minimum_Dispersion.h"
#include "ReplicaProxy.h"
ACE_RCSID(orbsvcs, Minimum_Dispersion, "$Id$")
Minimum_Dispersion_Strategy::Minimum_Dispersion_Strategy (void)
: proxies_ ()
{
}
Minimum_Dispersion_Strategy::~Minimum_Dispersion_Strategy (void)
{
// @@ Ossama: more code that is not thread safe
ReplicaProxySetIterator begin = this->proxies_.begin ();
ReplicaProxySetIterator end = this->proxies_.end ();
for (ReplicaProxySetIterator i = begin;
i != end;
++i)
{
// Decrease reference count on each proxy servant in the set.
(*i)->_remove_ref ();
}
}
CORBA::Object_ptr
Minimum_Dispersion_Strategy::replica (CORBA::Environment &ACE_TRY_ENV)
{
// @@ Ossama: more code that is not thread safe
while (!this->proxies_.is_empty ())
{
ReplicaProxySetIterator begin = this->proxies_.begin ();
ReplicaProxySetIterator end = this->proxies_.end ();
ReplicaProxySetIterator i = begin;
ReplicaProxy_Impl * proxy = (*i);
float d = (*i)->current_load ();
for (++i ; i != end; ++i)
{
if (d > (*i)->current_load ())
{
proxy = *i;
d = (*i)->current_load ();
}
}
// @@ Ossama: we should setup a timeout policy here...
ACE_TRY
{
// Before returning an object reference to the client
// validate it first.
CORBA::Object_var object =
proxy->replica ();
CORBA::Boolean non_existent =
object->_non_existent (ACE_TRY_ENV);
ACE_TRY_CHECK;
if (!non_existent)
{
return object._retn ();
}
}
ACE_CATCHANY
{
}
ACE_ENDTRY;
// @@ Ossama: a bit melodramatic, we remove the object if *any*
// exception is thrown. If the object really does not exist (we
// get non_existent==1) then this is exactly what we want to do,
// but if we get something like TRANSIENT we may want to do
// something less drastic, or at least strategize it ;-)
this->proxies_.remove (proxy);
}
// @@ What do we do if the set is empty?
ACE_THROW_RETURN (CORBA::OBJECT_NOT_EXIST (),
CORBA::Object::_nil ());
}
int
Minimum_Dispersion_Strategy::insert (ReplicaProxy_Impl *proxy)
{
// @@ Ossama: more code that is not thread safe
return this->proxies_.insert (proxy);
}
int
Minimum_Dispersion_Strategy::remove (ReplicaProxy_Impl *proxy)
{
// @@ Ossama: more code that is not thread safe
return this->proxies_.remove (proxy);
}
void
Minimum_Dispersion_Strategy::load_changed (ReplicaProxy_Impl *proxy,
CORBA::Environment &ACE_TRY_ENV)
{
// @@ Ossama: more code that is not thread safe
if (this->proxies_.is_empty ())
return;
ReplicaProxySetIterator begin = this->proxies_.begin ();
ReplicaProxySetIterator end = this->proxies_.end ();
float s = 0;
CORBA::ULong n = 0;
ReplicaProxySetIterator i = begin;
for (;i != end; ++i)
{
s += (*i)->current_load ();
n++;
}
float avg = s / n;
float cl = proxy->current_load ();
if (avg == 0)
return;
float relative_load = cl / avg;
// @@ 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 (relative_load > 1 + 1.5F / n)
{
proxy->has_high_load_ = 1;
proxy->control_->high_load_advisory (ACE_TRY_ENV);
ACE_CHECK;
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 (proxy->has_high_load_ && relative_load < 1 + 0.9F / n)
{
proxy->has_high_load_ = 0;
proxy->control_->nominal_load_advisory (ACE_TRY_ENV);
ACE_CHECK;
}
}
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