How to use

VERIFY_SUSPECT

in

org.jgroups.protocols

/**
 * Sends ARE_YOU_DEAD message to suspected_mbr, wait for return or timeout
 */
protected void verifySuspect(Collection<Address> mbrs) {
  if(mbrs == null || mbrs.isEmpty())
    return;
  if(addSuspects(mbrs)) {
    startTimer(); // start timer before we send out are you dead messages
    log.trace("verifying that %s %s dead", mbrs, mbrs.size() == 1? "is" : "are");
  }
  for(Address mbr: mbrs) {
    for(int i=0; i < num_msgs; i++) {
      Message msg=new Message(mbr).setFlag(Message.Flag.INTERNAL)
       .putHeader(this.id, new VerifyHeader(VerifyHeader.ARE_YOU_DEAD, local_addr));
      down_prot.down(msg);
    }
  }
}

public Object up(Event evt) {
  switch(evt.getType()) {
    case Event.SUSPECT:  // it all starts here ...
      // todo: change to collections in 4.1
      Collection<Address> s=evt.arg() instanceof Address? Collections.singletonList(evt.arg()) : evt.arg();
      if(s == null)
        return null;
      s.remove(local_addr); // ignoring suspect of self
      if(use_icmp)
        s.forEach(this::verifySuspectWithICMP);
      else
        verifySuspect(s);
      return null;  // don't pass up; we will decide later (after verification) whether to pass it up
    case Event.CONFIG:
      if(bind_addr == null) {
        Map<String,Object> config=evt.getArg();
        bind_addr=(InetAddress)config.get("bind_addr");
      }
  }
  return up_prot.up(evt);
}

public Object down(Event evt) {
  switch(evt.getType()) {
    case Event.SET_LOCAL_ADDRESS:
      local_addr=evt.getArg();
      break;
    case Event.VIEW_CHANGE:
      View v=evt.getArg();
      adjustSuspectedMembers(v.getMembers());
      break;
  }
  return down_prot.down(evt);
}

protected void verifySuspectWithICMP(Address suspected_mbr) {
  InetAddress host=suspected_mbr instanceof IpAddress? ((IpAddress)suspected_mbr).getIpAddress() : null;
  if(host == null)
    throw new IllegalArgumentException("suspected_mbr is not of type IpAddress - FD_ICMP only works with these");
  try {
    if(log.isTraceEnabled())
      log.trace("pinging host " + suspected_mbr + " using interface " + intf);
    long start=getCurrentTimeMillis(), stop;
    boolean rc=host.isReachable(intf, 0, (int)timeout);
    stop=getCurrentTimeMillis();
    if(rc) // success
      log.trace("successfully received response from " + host + " (after " + (stop-start) + "ms)");
    else { // failure
      log.debug("failed pinging " + suspected_mbr + " after " + (stop-start) + "ms; passing up SUSPECT event");
      removeSuspect(suspected_mbr);
      up_prot.up(new Event(Event.SUSPECT, Collections.singletonList(suspected_mbr)));
    }
  }
  catch(Exception ex) {
    log.error(Util.getMessage("FailedPinging"),suspected_mbr, ex);
  }
}

  verifySuspect(suspected_mbr);
else
  verifySuspectWithICMP(suspected_mbr);
return null;  // don't pass up; we will decide later (after verification) whether to pass it up
      return null;
    unsuspect(hdr.from);
    return null;

public Object up(Message msg) {
  VerifyHeader hdr=msg.getHeader(this.id);
  if(hdr == null)
    return up_prot.up(msg);
  switch(hdr.type) {
    case VerifyHeader.ARE_YOU_DEAD:
      if(hdr.from == null) {
        log.error(Util.getMessage("AREYOUDEADHdrFromIsNull"));
        return null;
      }
      Address target=use_mcast_rsps? null : hdr.from;
      for(int i=0; i < num_msgs; i++) {
        Message rsp=new Message(target).setFlag(Message.Flag.INTERNAL)
         .putHeader(this.id, new VerifyHeader(VerifyHeader.I_AM_NOT_DEAD, local_addr));
        down_prot.down(rsp);
      }
      return null;
    case VerifyHeader.I_AM_NOT_DEAD:
      if(hdr.from == null) {
        log.error(Util.getMessage("IAMNOTDEADHdrFromIsNull"));
        return null;
      }
      unsuspect(hdr.from);
      return null;
  }
  return null;
}

public void unsuspect(Address mbr) {
  boolean removed=mbr != null && removeSuspect(mbr);
  if(removed) {
    log.trace("member " + mbr + " was unsuspected");
    down_prot.down(new Event(Event.UNSUSPECT, mbr));
    up_prot.up(new Event(Event.UNSUSPECT, mbr));
  }
}

/**
 * Sends ARE_YOU_DEAD message to suspected_mbr, wait for return or timeout
 */
void verifySuspect(Address mbr) {
  Message msg;
  if(mbr == null) return;
  synchronized(suspects) {
    if(suspects.containsKey(mbr))
      return;
    suspects.put(mbr, new Long(System.currentTimeMillis()));
  }
  // moved out of synchronized statement (bela): http://jira.jboss.com/jira/browse/JGRP-302
  if(log.isTraceEnabled()) log.trace("verifying that " + mbr + " is dead");
  for(int i=0; i < num_msgs; i++) {
    msg=new Message(mbr, null, null);
    msg.setFlag(Message.OOB);
    msg.putHeader(name, new VerifyHeader(VerifyHeader.ARE_YOU_DEAD, local_addr));
    down_prot.down(new Event(Event.MSG, msg));
  }
  if(timer == null)
    startTimer();
}

protected synchronized void startTimer() {
  timer=getThreadFactory().newThread(this,"VERIFY_SUSPECT.TimerThread");
  timer.setDaemon(true);
  timer.start();
}

new FD_SOCK(),
new FD_ALL(),
new VERIFY_SUSPECT(),
new BARRIER(),
new NAKACK2(),

public synchronized void stop() {
  clearSuspects();
  running=false;
  if(timer != null && timer.isAlive()) {
    Thread tmp=timer;
    timer=null;
    tmp.interrupt();
  }
  timer=null;
}

public Object up(Message msg) {
  VerifyHeader hdr=msg.getHeader(this.id);
  if(hdr == null)
    return up_prot.up(msg);
  switch(hdr.type) {
    case VerifyHeader.ARE_YOU_DEAD:
      if(hdr.from == null) {
        log.error(Util.getMessage("AREYOUDEADHdrFromIsNull"));
        return null;
      }
      Address target=use_mcast_rsps? null : hdr.from;
      for(int i=0; i < num_msgs; i++) {
        Message rsp=new Message(target).setFlag(Message.Flag.INTERNAL)
         .putHeader(this.id, new VerifyHeader(VerifyHeader.I_AM_NOT_DEAD, local_addr));
        down_prot.down(rsp);
      }
      return null;
    case VerifyHeader.I_AM_NOT_DEAD:
      if(hdr.from == null) {
        log.error(Util.getMessage("IAMNOTDEADHdrFromIsNull"));
        return null;
      }
      unsuspect(hdr.from);
      return null;
  }
  return null;
}

public void unsuspect(Address mbr) {
  boolean removed=mbr != null && removeSuspect(mbr);
  if(removed) {
    log.trace("member " + mbr + " was unsuspected");
    down_prot.down(new Event(Event.UNSUSPECT, mbr));
    up_prot.up(new Event(Event.UNSUSPECT, mbr));
  }
}

protected synchronized void startTimer() {
  if(timer == null || !timer.isAlive()) {            
    timer=getThreadFactory().newThread(this,"VERIFY_SUSPECT.TimerThread");
    timer.setDaemon(true);
    timer.start();
  }
}

new FD_SOCK(),
new FD_ALL(),
new VERIFY_SUSPECT(),
new BARRIER(),
new NAKACK2(),

/**
 * Sends ARE_YOU_DEAD message to suspected_mbr, wait for return or timeout
 */
void verifySuspect(Collection<Address> mbrs) {
  if(mbrs == null || mbrs.isEmpty())
    return;
  boolean added=addSuspects(mbrs);
  if(added) {
    startTimer(); // start timer before we send out are you dead messages
    log.trace("verifying that %s %s dead", mbrs, mbrs.size() == 1? "is" : "are");
  }
  for(Address mbr: mbrs) {
    for(int i=0; i < num_msgs; i++) {
      Message msg=new Message(mbr).setFlag(Message.Flag.INTERNAL)
       .putHeader(this.id, new VerifyHeader(VerifyHeader.ARE_YOU_DEAD, local_addr));
      down_prot.down(msg);
    }
  }
}

public Object up(Event evt) {
  switch(evt.getType()) {
    case Event.SUSPECT:  // it all starts here ...
      // todo: change to collections in 4.1
      Collection<Address> s=evt.arg() instanceof Address? Collections.singletonList(evt.arg()) : evt.arg();
      if(s == null)
        return null;
      s.remove(local_addr); // ignoring suspect of self
      if(!use_icmp)
        verifySuspect(s);
      else
        s.forEach(this::verifySuspectWithICMP);
      return null;  // don't pass up; we will decide later (after verification) whether to pass it up
    case Event.CONFIG:
      if(bind_addr == null) {
        Map<String,Object> config=evt.getArg();
        bind_addr=(InetAddress)config.get("bind_addr");
      }
  }
  return up_prot.up(evt);
}

void verifySuspectWithICMP(Address suspected_mbr) {
  InetAddress host=suspected_mbr instanceof IpAddress? ((IpAddress)suspected_mbr).getIpAddress() : null;
  if(host == null)
    throw new IllegalArgumentException("suspected_mbr is not of type IpAddress - FD_ICMP only works with these");
  try {
    if(log.isTraceEnabled())
      log.trace("pinging host " + suspected_mbr + " using interface " + intf);
    long start=System.currentTimeMillis(), stop;
    boolean rc=host.isReachable(intf, 0, (int)timeout);
    stop=System.currentTimeMillis();
    if(rc) // success
      log.trace("successfully received response from " + host + " (after " + (stop-start) + "ms)");
    else { // failure
      log.debug("failed pinging " + suspected_mbr + " after " + (stop-start) + "ms; passing up SUSPECT event");
      removeSuspect(suspected_mbr);
      up_prot.up(new Event(Event.SUSPECT, Collections.singletonList(suspected_mbr)));
    }
  }
  catch(Exception ex) {
    log.error(Util.getMessage("FailedPinging"),suspected_mbr, ex);
  }
}

public Object down(Event evt) {
  switch(evt.getType()) {
    case Event.SET_LOCAL_ADDRESS:
      local_addr=evt.getArg();
      break;
    case Event.VIEW_CHANGE:
      View v=evt.getArg();
      adjustSuspectedMembers(v.getMembers());
      break;
  }
  return down_prot.down(evt);
}