/**
* SAMOA - PROTOCOL FRAMEWORK
* Copyright (C) 2005 Olivier Rütti (EPFL) (olivier.rutti@a3.epfl.ch)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
package seqSamoa.protocols.fd;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import seqSamoa.Message;
import seqSamoa.ProtocolModule;
import seqSamoa.ProtocolStack;
import seqSamoa.Service;
import seqSamoa.ServiceCallOrResponse;
import seqSamoa.AtomicTask;
import seqSamoa.exceptions.AlreadyExistingProtocolModuleException;
import seqSamoa.exceptions.NotScheduledTaskException;
import seqSamoa.services.fd.FD;
import seqSamoa.services.fd.FDCallParameters;
import seqSamoa.services.fd.FDResponseParameters;
import seqSamoa.services.udp.UDP;
import seqSamoa.services.udp.UDPCallParameters;
import uka.transport.Transportable;
import framework.Constants;
import framework.GroupCommEventArgs;
import framework.GroupCommException;
import framework.PID;
import framework.libraries.Timer;
import framework.libraries.Trigger;
import framework.libraries.serialization.TSet;
import groupcomm.common.fd.FDHandler;
/**
* This class implement a Protocol that detect distant process failure. It
* implement the failure detector needed by the consensus protocol described by
* Chandra and Toueg.
*
* This Protocol need a Protocol that implements UDP transport.
*
* The service implemented is FD (described in util/Services.java)
*/
public class ProtocolPing extends ProtocolModule implements Trigger, Timer {
final static int MAX_PROCESSES = 7;
// Service provided
private FD fd;
// Service required
private Service<UDPCallParameters, Object> udp;
// The object containig the FD algorithm
private FDHandler handlers = null;
// Timers scheduled
private Map<Transportable, AtomicTask> timers = null;
// The Executer
// It start to monitor the processes in parameters
protected FD.Executer fdExecuter;
// The Listener
// It wait for UDP message
protected UDP.Listener udpListener;
// The fd call COR
private ServiceCallOrResponse fdCallCOR;
/**
* Constructor. <br>
*
* @param name
* Name of the layer
* @param stack
* The stack in which the module will be
* @param timeout
* The timeout for ping messages
* @param retries
* The number of retries before suspecting
*/
@SuppressWarnings("unchecked")
public ProtocolPing(String name, ProtocolStack stack, int timeout, int retries,
FD fd, Service<? extends UDPCallParameters, ? extends Object> udp) throws AlreadyExistingProtocolModuleException {
super(name, stack);
handlers = new FDHandler(this, this, stack.getPID(), timeout, retries);
timers = new HashMap<Transportable, AtomicTask>();
this.fd = fd;
this.udp = (Service<UDPCallParameters, Object>) udp;
this.fdCallCOR = ServiceCallOrResponse.createServiceCallOrResponse(this.fd, true);
LinkedList<ServiceCallOrResponse> initiatedFD = new LinkedList<ServiceCallOrResponse>();
for (int i=0;i<MAX_PROCESSES;i++)
initiatedFD.add(ServiceCallOrResponse.createServiceCallOrResponse(udp, true));
initiatedFD.add(ServiceCallOrResponse.createServiceCallOrResponse(fd, false));
fdExecuter = fd.new Executer(this, initiatedFD) {
public void evaluate(FDCallParameters params, Message dmessage) {
synchronized (this.parent) {
GroupCommEventArgs ga = new GroupCommEventArgs();
ga.addLast(params.startMonitoring);
ga.addLast(params.stopMonitoring);
try {
handlers.handleStartStopMonitor(ga);
} catch (GroupCommException ex) {
throw new RuntimeException("ProtocolPing: fdExecuter: "
+ ex.getMessage());
}
}
}
};
LinkedList<ServiceCallOrResponse> initiatedUdp = new LinkedList<ServiceCallOrResponse>();
initiatedUdp.add(ServiceCallOrResponse.createServiceCallOrResponse(udp, true));
initiatedUdp.add(ServiceCallOrResponse.createServiceCallOrResponse(fd, false));
udpListener = this.udp.new Listener(this, initiatedUdp) {
public void evaluate(Object infos, Transportable response) {
synchronized (this.parent) {
GroupCommEventArgs ga = new GroupCommEventArgs();
ga.addLast(response);
handlers.handleAlive(ga);
}
}
};
}
synchronized public void dump(OutputStream stream) {
handlers.dump(stream);
}
/**
* Manage the triggering of the events
*/
public void trigger(int type, GroupCommEventArgs e) {
switch (type) {
case Constants.ALIVE:
Transportable message = e.remove(0);
UDPCallParameters params = new UDPCallParameters((PID) e.remove(0));
udp.call(params, new Message(message, udpListener));
break;
case Constants.SUSPECT:
FDResponseParameters infos = new FDResponseParameters((TSet) e
.remove(0));
fd.response(infos, null);
break;
default:
// This shouldn't ever happen
throw new RuntimeException("ProtocolPing: trigger: "
+ "Unexpected event type");
}
}
// Interface for the timers
synchronized public void schedule(final Transportable key, boolean periodic,
int time) {
if (!periodic)
throw new RuntimeException("ProtocolPing: schedule: Non-periodic "
+ "timers not supported. Discarding it.");
if (!timers.containsKey(key)) {
// There is no entry in the map
// Create the entry and start the timer
AtomicTask trigger = new AtomicTask() {
public void execute() {
timeout(key);
}
public ServiceCallOrResponse getCOR() {
return fdCallCOR;
}
};
timers.put(key, trigger);
stack.getScheduler().schedule(trigger, periodic, time);
} else {
throw new RuntimeException("ProtocolPing:schedule: Suspect "
+ "Task already scheduled!");
}
}
synchronized public void cancel(Transportable key) {
try{
stack.getScheduler().cancel(timers.remove(key));
} catch (NotScheduledTaskException ex){
throw new RuntimeException("ProtocolPing: cancel: The task is not"
+ " currently scheduled");
}
}
synchronized public void reset(Transportable key) {
try {
stack.getScheduler().reset(timers.get(key));
} catch (NotScheduledTaskException ex) {
throw new RuntimeException("ProtocolPing: reset: The task is not"
+ " currently scheduled");
}
}
synchronized private void timeout(Object o) {
GroupCommEventArgs ga = new GroupCommEventArgs();
final Transportable key = (Transportable) o;
if (!timers.containsKey(key))
// Timer already canceled
return;
ga.add(key);
handlers.handleTimeOut(ga);
}
}