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// -*- C++ -*-
// $Id$
#include "Round_Robin_Strategy.h"
#include "ReplicaProxy.h"
ACE_RCSID (LoadBalancing,
Round_Robin_Strategy,
"$Id$")
TAO_LB_Round_Robin_Strategy::TAO_LB_Round_Robin_Strategy (void)
: proxies_ (),
next_replica_ (this->proxies_.begin ()),
lock_ ()
{
}
TAO_LB_Round_Robin_Strategy::~TAO_LB_Round_Robin_Strategy (void)
{
ACE_MT (ACE_GUARD (TAO_SYNCH_MUTEX,
guard,
this->lock_));
// @@ Are the objects deactivated from the POA? And shouldn't this
// be done by the LoadBalancing strategy *before* the destructor is
// invoked?
TAO_LB_ReplicaProxySetIterator begin = this->proxies_.begin ();
TAO_LB_ReplicaProxySetIterator end = this->proxies_.end ();
for (TAO_LB_ReplicaProxySetIterator i = begin;
i != end;
++i)
{
// Decrease reference count on each proxy servant in the set.
(*i)->_remove_ref ();
}
}
CORBA::Object_ptr
TAO_LB_Round_Robin_Strategy::replica (CORBA::Environment &ACE_TRY_ENV)
ACE_THROW_SPEC ((CORBA::SystemException))
{
ACE_GUARD_RETURN (TAO_SYNCH_MUTEX,
guard,
this->lock_,
CORBA::Object::_nil ());
if (this->proxies_.is_empty ())
{
// @@ What do we do if the set is empty?
// @@ Ossama: i'm throwing the OBJECT_NOT_EXIST exception, but
// maybe TRANSIENT is a better choice.... please read the
// relevant section of the CORBA spec and let me know what you
// think.
ACE_THROW_RETURN (CORBA::OBJECT_NOT_EXIST (),
CORBA::Object::_nil ());
}
// If we're at the end of the Replica set, then rewind to the
// beginning of the set.
if (this->next_replica_ == this->proxies_.end ())
this->next_replica_ = this->proxies_.begin ();
TAO_LB_ReplicaProxy * proxy_servant = *(this->next_replica_);
// Advance to the next Replica in the set in preparation for the
// next call to this method.
this->next_replica_++;
// @@ Ossama: once we select a replica, shouldn't we temporarily
// change its load so it does not get swamped with all the new
// clients. Think about the current scenario:
// - Replica A has the lowest load, by far.
// - 5 clients connect at the same time.
// - If the load on A does not grow fast enough all 5 clients will
// end up on replica A, and then they will be kicked out and
// shuffled around.
// While if we bump the load for a few seconds then the next client
// will go to other place. Or set a flag that says 'load
// invalidated, waiting for an update' (i like the latter better).
return proxy_servant->replica ();
}
int
TAO_LB_Round_Robin_Strategy::insert (TAO_LB_ReplicaProxy *proxy)
{
ACE_MT (ACE_GUARD_RETURN (TAO_SYNCH_MUTEX,
guard,
this->lock_,
-1));
int r = this->proxies_.insert (proxy);
this->next_replica_ = this->proxies_.begin ();
return r;
}
int
TAO_LB_Round_Robin_Strategy::remove (TAO_LB_ReplicaProxy *proxy)
{
ACE_MT (ACE_GUARD_RETURN (TAO_SYNCH_MUTEX,
guard,
this->lock_,
-1));
int r = this->proxies_.remove (proxy);
this->next_replica_ = this->proxies_.begin ();
return r;
}
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