// "peoSyncIslandMig.h"

// (c) OPAC Team, LIFL, August 2005

/* 
   Contact: paradiseo-help@lists.gforge.inria.fr
*/

#ifndef __peoSyncIslandMig_h
#define __peoSyncIslandMig_h


#include <queue>
#include <cassert>

#include <eoPeriodicContinue.h>

#include <utils/eoUpdater.h>

#include <eoContinue.h>
#include <eoSelect.h>
#include <eoReplacement.h>
#include <eoPop.h>

#include "core/topology.h"
#include "core/thread.h"
#include "core/eoPop_comm.h"
#include "core/peo_debug.h"


//! Class providing the basis for the synchronous island migration model.

//! The peoSyncIslandMig class offers the elementary basis for implementating a
//! synchronous island migration model - requires the specification of several basic
//! parameters, i.e. frequency of the migrations, selection and replacement strategies,
//! a topological model and the source and destination population for the migrating individuals.
//! The main difference as opposed to the asynchronous migration model is the synchronization step
//! performed after selecting and sending the emigrant individuals. 
//!
//! The migration operator is called at the end of each generation of an evolutionary algorithms
//! as a checkpoint object - the following code exposes the structure of a classic evolutionary algorithm:
//!
//!	<table style="border:none; border-spacing:0px;text-align:left; vertical-align:top; font-size:8pt;" border="0">
//!	<tr><td><b>do</b> { &nbsp;</td> <td> &nbsp; </td></tr>
//!	<tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; select( population, offsprings ); &nbsp;</td> <td>// select the offsprings from the current population</td></tr>
//!	<tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; transform( offsprings ); &nbsp;</td> <td>// crossover and mutation operators are applied on the selected offsprings</td></tr>
//!	<tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; evaluate( offsprings ); &nbsp;</td> <td>// evaluation step of the resulting offspring</td></tr>
//!	<tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; replace( population, offsprings ); &nbsp;</td> <td>// replace the individuals in the current population whith individuals from the offspring population, according to a specified replacement strategy</td></tr>
//!	<tr><td>} <b>while</b> ( eaCheckpointContinue( population ) ); &nbsp;</td> <td>// checkpoint operators are applied on the current population, including the migration operator, if any specified </td></tr>
//!	</table>
//!
//! Constructing a synchronous island migration model requires having defined (1) a topological migration model,
//! (2) the control parameters of the migration process, (3) a checkpoint object associated with an evolutionary algorithm,
//! and (4) an owner object must be set. The owner object must be derived from the <b>Runner</b> class (for example
//! a peoEA object represents a possible owner).
//! A simple example is offered bellow:
//!
//!	<ol>
//!		<li> topological model to be followed when performing migrations: <br/>
//!		<br/>
//!		<table style="border:none; border-spacing:0px;text-align:left; vertical-align:top; font-size:8pt;" border="0">
//!		<tr><td>RingTopology migTopology; &nbsp;</td> <td>// a simple ring topological model - each island communicates with two other islands</td></tr>
//!		</table>
//!		</li>
//!
//!		<li> the continuation criterion, selection and replacement strategy etc. are defined: <br/>
//!		<br/>
//!		<table style="border:none; border-spacing:0px; font-size:8pt;" border="0">
//!		<tr><td>eoPop< EOT > population( POP_SIZE, popInitializer ); &nbsp;</td> <td>// population of individuals to be used for the evolutionary algorithm</td></tr>
//!		<tr><td> &nbsp; </td> <td> &nbsp; </td></tr>
//!		<tr><td>eoRandomSelect< EOT > migSelectStrategy; &nbsp;</td> <td>// selection strategy - in this case a random selection is applied</td></tr>
//!		<tr><td>eoSelectNumber< EOT > migSelect( migSelectStrategy, MIG_SIZE ); &nbsp;</td> <td>// number of individuals to be selected using the specified strategy</td></tr>
//!		<tr><td>eoPlusReplacement< EOT > migReplace; &nbsp;</td> <td>// immigration strategy - the worse individuals in the destination population are replaced by the immigrant individuals</td></tr>
//!		<tr><td> &nbsp; </td> <td> &nbsp; </td></tr>
//!		<tr><td>peoSyncIslandMig< EOT > syncMigration(
//!			<br/> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; MIG_FREQ, migSelect, migReplace, migTopology,
//!			<br/> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; population, population
//!			<br/> ); &nbsp; </td>
//!			<td>// synchronous migration object - the emigrant individuals are selected from the same from population in which the immigrant individuals are being integrated </td></tr>
//!		</table>
//!		</li>
//!
//!		<li> creation of a checkpoint object as part of the definition of an evolutionary algoritm (details of th EA not given as being out of scope): <br/>
//!		<br/>
//!		<table style="border:none; border-spacing:0px;text-align:left; vertical-align:top; font-size:8pt;" border="0">
//!		<tr><td>... &nbsp;</td> <td> &nbsp; </td></tr>
//!		<tr><td>eoGenContinue< EOT > eaCont( NUM_GEN ); &nbsp;</td> <td>// the evolutionary algorithm will stop after NUM_GEN generations</td></tr>
//!		<tr><td>eoCheckPoint< EOT > eaCheckpointContinue( eaCont ); &nbsp;</td> <td>// number of individuals to be selected using the specified strategy</td></tr>
//!		<tr><td>... &nbsp;</td> <td> &nbsp; </td></tr>
//!		<tr><td>eaCheckpointContinue.add( syncMigration ); &nbsp;</td> <td>// adding the migration operator as checkpoint element</td></tr>
//!		<tr><td>... &nbsp;</td> <td> &nbsp; </td></tr>
//!		</table>
//!		</li>
//!
//!		<li> definition of an owner evolutionary algorithm (an object inheriting the <b>Runner</b> class): <br/>
//!		<br/>
//!		<table style="border:none; border-spacing:0px;text-align:left; vertical-align:top; font-size:8pt;" border="0">
//!		<tr><td>peoEA< EOT > eaAlg( eaCheckpointContinue, eaPopEval, eaSelect, eaTransform, eaReplace); &nbsp;</td> <td>// evolutionary algorithm having as checkpoint the eaCheckpointContinue object defined above </td></tr>
//!		<tr><td>syncMigration.setOwner( eaAlg ); &nbsp;</td> <td>// setting the evolutionary algorithm as owner of the migration object </td></tr>
//!		<tr><td>eaAlg( population ); &nbsp;</td> <td>// applying the evolutionary algorithm on a given population </td></tr>
//!		</table>
//!		</li>
//!	</ol>
//!
//! The source and the destination population for the migration object were specified as being the same, in step no. 2,
//! as we are usually interested in selecting the emigrants and integrating the immigrant individuals from and in, respectively, one unique
//! population, iteratively evolved by an evolutionary algorithm. There is no restriction in having two distinct populations
//! as source and destination for the emigrant and immigrant individuals respectively.
//!
//! The above steps only create a synchronous migration object associated to an evolutionary algorithm. The creation of several
//! islands requires the reiteration of the steps 2 through 4 for creating distinct algorithms, with distinct populations and
//! the associated distinctly parametrized migration objects. The interconnecting element is the underlying topology, defined at step 1
//! (the same C++ migTopology object has to be passed as parameter for all the migration objects, in order to interconnect them).
template< class EOT > class peoSyncIslandMig : public Cooperative, public eoUpdater {

public:

	//! Constructor for the peoSyncIslandMig class; the characteristics of the migration model are defined
	//! through the specified parameters - out of the box objects provided in EO, etc., or custom, derived objects may be passed as parameters.
	//!
	//! @param unsigned __frequency - frequency of the migrations - the migrations occur periodically;
	//! @param eoSelect< EOT >& __select - selection strategy to be applied for constructing a list of emigrant individuals out of the source population;
	//! @param eoReplacement< EOT >& __replace - replacement strategy used for integrating the immigrant individuals in the destination population;
	//! @param Topology& __topology - topological model to be followed when performing migrations;
	//! @param eoPop< EOT >& __source - source population from which the emigrant individuals are selected;
	//! @param eoPop< EOT >& __destination - destination population in which the immigrant population are integrated.
	peoSyncIslandMig(
				unsigned __frequency,
				eoSelect< EOT >& __select,
				eoReplacement< EOT >& __replace,
				Topology& __topology,
				eoPop< EOT >& __source,
				eoPop< EOT >& __destination
	);

	//! Function operator to be called as checkpoint for performing the migration step. The emigrant individuals are selected
	//! from the source population and sent to the next island (defined by the topology object) while the immigrant 
	//! individuals are integrated in the destination population. There is no need to explicitly call the function - the
	//! wrapper checkpoint object (please refer to the above example) will perform the call when required.
	void operator()();

	//! Auxiliary function dealing with sending the emigrant individuals. There is no need to explicitly call the function.
	void pack();
	//! Auxiliary function dealing with receiving immigrant individuals. There is no need to explicitly call the function.
	void unpack();

	//! Auxiliary function dealing with migration notifications. There is no need to explicitly call the function.
	void notifySending();


private:

	void emigrate();
	void immigrate();


private:

	eoPeriodicContinue< EOT > cont;
	eoSelect< EOT >& select; 	// selection strategy
	eoReplacement< EOT >& replace;	// replacement strategy
	Topology& topology; 		// neighboring topology

	// source and target populations
	eoPop< EOT >& source;
	eoPop< EOT >& destination;

	// immigrants & emigrants in the queue
	std :: queue< eoPop< EOT > > imm;
	std :: queue< eoPop< EOT > > em;

	std :: queue< Cooperative* > coop_em;

	sem_t sync;
};


template< class EOT > peoSyncIslandMig< EOT > :: peoSyncIslandMig(

		unsigned __frequency,
		eoSelect< EOT >& __select,
		eoReplacement< EOT >& __replace,
		Topology& __topology,
		eoPop< EOT >& __source,
		eoPop< EOT >& __destination

	) : cont( __frequency ), select( __select ), replace( __replace ), topology( __topology ), source( __source ), destination( __destination ) 
{

	__topology.add( *this );
	sem_init( &sync, 0, 0 );
}


template< class EOT > void peoSyncIslandMig< EOT > :: pack() {

	lock(); {

		 :: pack( coop_em.front()->getKey() );
		 :: pack( em.front() );
		coop_em.pop();
		em.pop();
	}
	unlock();
}


template< class EOT > void peoSyncIslandMig< EOT > :: unpack() {

	lock(); {

		eoPop< EOT > mig;
		 :: unpack( mig );
		imm.push( mig );
	}
	unlock();

	sem_post( &sync );
}


template< class EOT > void peoSyncIslandMig< EOT > :: emigrate() {

	std :: vector< Cooperative* > in, out;
	topology.setNeighbors( this, in, out );
	
	for ( unsigned i = 0; i < out.size(); i ++ ) {

		eoPop< EOT > mig;
		select( source, mig );
		em.push( mig );
		coop_em.push( out[ i ] );
		send( out[ i ] );
		printDebugMessage( "sending some emigrants." );
	}
}


template< class EOT > void peoSyncIslandMig< EOT > :: immigrate() {

	lock(); {

		assert( imm.size() );
		replace( destination, imm.front() ) ;
		imm.pop();
		printDebugMessage( "receiving some immigrants." );
	}
	unlock();
}


template< class EOT > void peoSyncIslandMig< EOT > :: operator()() {

	if ( !cont( source ) ) {
	
		// sending emigrants
		emigrate();
		stop();

		// synchronizing
		sem_wait( &sync );
		getOwner()->setActive();

		// receiving immigrants
		immigrate();
	}
}


template< class EOT > void peoSyncIslandMig< EOT > :: notifySending() {

	lock(); {

		if ( imm.empty() ) {

			printDebugMessage( "entering pasive mode\n" );
			getOwner()->setPassive();
		}
	}
	unlock();

	resume();
}


#endif