package org.jgroups.protocols;
import org.jgroups.Address;
import org.jgroups.Event;
import org.jgroups.Message;
import org.jgroups.PhysicalAddress;
import org.jgroups.util.Responses;
import org.jgroups.util.UUID;
import java.io.InterruptedIOException;
import java.util.List;
/**
* The PING protocol retrieves the initial membership by mcasting a discovery request (via the multicast capable
* transport) to all current cluster members<p/>
* The responses should allow us to determine the coordinator which we have to contact, e.g. in case we want to join
* the group. When we are a server (after having received the BECOME_SERVER event), we'll respond to discovery requests
* with a discovery response.
* @author Bela Ban
*/
public class PING extends Discovery {
public boolean isDynamic() {
return true;
}
public void findMembers(List<Address> members, boolean initial_discovery, Responses responses) {
try {
sendDiscoveryRequest(cluster_name, members);
}
catch(InterruptedIOException ie) {
;
}
catch(InterruptedException ex) {
;
}
catch(Throwable ex) {
log.error("failed sending discovery request", ex);
}
}
protected void sendDiscoveryRequest(String cluster_name, List<Address> members_to_find) throws Exception {
PhysicalAddress physical_addr=(PhysicalAddress)down(new Event(Event.GET_PHYSICAL_ADDRESS, local_addr));
// https://issues.jboss.org/browse/JGRP-1670
PingData data=new PingData(local_addr, false, UUID.get(local_addr), physical_addr);
PingHeader hdr=new PingHeader(PingHeader.GET_MBRS_REQ).clusterName(cluster_name);
if(members_to_find != null && members_to_find.size() <= max_members_in_discovery_request)
data.mbrs(members_to_find);
// message needs to have DONT_BUNDLE flag: if A sends message M to B, and we need to fetch B's physical
// address, then the bundler thread blocks until the discovery request has returned. However, we cannot send
// the discovery *request* until the bundler thread has returned from sending M
Message msg=new Message(null).putHeader(getId(),hdr).setBuffer(marshal(data))
.setFlag(Message.Flag.INTERNAL,Message.Flag.DONT_BUNDLE,Message.Flag.OOB)
.setTransientFlag(Message.TransientFlag.DONT_LOOPBACK);
sendMcastDiscoveryRequest(msg);
}
protected void sendMcastDiscoveryRequest(Message msg) {
down_prot.down(new Event(Event.MSG, msg));
}
}