package org.jgroups.protocols;
import org.jgroups.*;
import org.jgroups.stack.Protocol;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Vector;
/**
* The coordinator attaches a small header to each (or every nth) message. If another coordinator <em>in the
* same group</em> sees the message, it will initiate the merge protocol immediately by sending a MERGE
* event up the stack.
* @author Bela Ban, Aug 25 2003
*/
public class MERGEFAST extends Protocol {
Address local_addr=null;
boolean is_coord=false;
static final String name="MERGEFAST";
public String getName() {
return name;
}
public Object down(Event evt) {
if(is_coord == true && evt.getType() == Event.MSG && local_addr != null) {
Message msg=(Message)evt.getArg();
Address dest=msg.getDest();
if(dest == null || dest.isMulticastAddress()) {
msg.putHeader(getName(), new MergefastHeader(local_addr));
}
}
if(evt.getType() == Event.VIEW_CHANGE) {
handleViewChange((View)evt.getArg());
}
return down_prot.down(evt);
}
public Object up(Event evt) {
switch(evt.getType()) {
case Event.SET_LOCAL_ADDRESS:
local_addr=(Address)evt.getArg();
break;
case Event.MSG:
if(is_coord == false) // only handle message if we are coordinator
break;
Message msg=(Message)evt.getArg();
MergefastHeader hdr=(MergefastHeader)msg.getHeader(name);
up_prot.up(evt);
if(hdr != null && local_addr != null) {
Address other_coord=hdr.coord;
if(!local_addr.equals(other_coord)) {
sendUpMerge(new Address[]{local_addr, other_coord});
}
}
return null; // event was already passed up
case Event.VIEW_CHANGE:
handleViewChange((View)evt.getArg());
break;
}
return up_prot.up(evt);
}
void handleViewChange(View v) {
Vector mbrs;
if(local_addr == null)
return;
mbrs=v.getMembers();
is_coord=mbrs != null && !mbrs.isEmpty() && local_addr.equals(mbrs.firstElement());
}
/**
* @todo avoid sending up too many MERGE events.
*/
void sendUpMerge(Address[] addresses) {
Vector v=new Vector(11);
for(int i=0; i < addresses.length; i++) {
Address addr=addresses[i];
v.add(addr);
}
up_prot.up(new Event(Event.MERGE, v));
}
public static class MergefastHeader extends Header {
Address coord=null;
public MergefastHeader() {
}
public MergefastHeader(Address coord) {
this.coord=coord;
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(coord);
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
coord=(Address)in.readObject();
}
}
}