org.jgroups.protocols.SEQUENCER2 Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
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package org.jgroups.protocols;
import org.jgroups.*;
import org.jgroups.annotations.Experimental;
import org.jgroups.annotations.MBean;
import org.jgroups.annotations.ManagedAttribute;
import org.jgroups.annotations.ManagedOperation;
import org.jgroups.stack.Protocol;
import org.jgroups.util.Bits;
import org.jgroups.util.MessageBatch;
import org.jgroups.util.Table;
import org.jgroups.util.Util;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.BiConsumer;
import java.util.function.Supplier;
/**
* Implementation of total order protocol using a sequencer_uum.
*
* Todo 1: on a sequencer change, the new coordinator needs to determine the highest seqno from all members
* Todo 2: on a sequencer change, if a member has pendindg messages in the forward-queue, they need to be resent
* Todo 3: this protocol is currently broken, as a new member doesn't get the highest seqno and thus creates its table
* at offset=0, which means it will queue all messages higher than 0, and eventually run out of memory!!!
*
* @author Bela Ban
* @edited Andrei Palade
*/
@Experimental
@MBean(description="Implementation of total order protocol using a sequencer (unicast-unicast-multicast)")
public class SEQUENCER2 extends Protocol {
protected volatile Address coord;
protected volatile View view;
protected volatile boolean is_coord=false;
protected final AtomicLong seqno=new AtomicLong(0); // only used by the sequencer
// messages to be multicast are added to this queue; when seqnos are received from the sequencer, we remove and
// send messages from the queue
protected final BlockingQueue fwd_queue=new LinkedBlockingQueue<>(20000); // make this configurable
// the number of seqno requests sent to the sequencer
protected final AtomicInteger seqno_reqs=new AtomicInteger(0);
protected volatile boolean running=true;
protected static final BiConsumer BATCH_ACCUMULATOR=MessageBatch::add;
@ManagedAttribute protected long request_msgs;
@ManagedAttribute protected long response_msgs;
@ManagedAttribute protected long bcasts_sent;
@ManagedAttribute protected long bcasts_received;
@ManagedAttribute protected long bcasts_delivered;
@ManagedAttribute protected long sent_requests;
@ManagedAttribute protected long received_requests;
@ManagedAttribute protected long sent_responses;
@ManagedAttribute protected long received_responses;
protected Table received_msgs = new Table<>();
@ManagedAttribute
public boolean isCoordinator() {return is_coord;}
public Address getCoordinator() {return coord;}
@ManagedAttribute(description="Number of messages in the forward-queue")
public int getFwdQueueSize() {return fwd_queue.size();}
@ManagedOperation
public void resetStats() {
request_msgs=response_msgs=bcasts_sent=bcasts_received=bcasts_delivered=0L;
sent_requests=received_requests=sent_responses=received_responses=0L; // reset number of sent and received requests and responses
}
public void start() throws Exception {
super.start();
running = true;
}
public void stop() {
running=false;
super.stop();
}
public Object down(Event evt) {
switch(evt.getType()) {
case Event.VIEW_CHANGE:
handleViewChange(evt.getArg());
break;
case Event.TMP_VIEW:
handleTmpView(evt.getArg());
break;
}
return down_prot.down(evt);
}
public Object down(Message msg) {
if(msg.getDest() != null || msg.isFlagSet(Message.Flag.NO_TOTAL_ORDER) || msg.isFlagSet(Message.Flag.OOB))
return down_prot.down(msg);
if(msg.getSrc() == null)
msg.setSrc(local_addr);
try {
fwd_queue.put(msg);
if(seqno_reqs.getAndIncrement() == 0) {
int num_reqs=seqno_reqs.get();
sendSeqnoRequest(num_reqs);
}
}
catch(InterruptedException e) {
if(!running)
return null;
throw new RuntimeException(e);
}
return null; // don't pass down
}
public Object up(Event evt) {
switch(evt.getType()) {
case Event.VIEW_CHANGE:
Object retval=up_prot.up(evt);
handleViewChange(evt.getArg());
return retval;
case Event.TMP_VIEW:
handleTmpView(evt.getArg());
break;
}
return up_prot.up(evt);
}
public Object up(Message msg) {
SequencerHeader hdr;
if(msg.isFlagSet(Message.Flag.NO_TOTAL_ORDER) || msg.isFlagSet(Message.Flag.OOB))
return up_prot.up(msg);
hdr=msg.getHeader(this.id);
if(hdr == null)
return up_prot.up(msg); // pass up
switch(hdr.type) {
case SequencerHeader.REQUEST:
if(!is_coord) {
log.error("%s: non-coord; dropping REQUEST request from %s", local_addr, msg.getSrc());
return null;
}
Address sender=msg.getSrc();
if(view != null && !view.containsMember(sender)) {
log.error("%s : dropping REQUEST from non-member %s; view=%s" + view, local_addr, sender, view);
return null;
}
long new_seqno=seqno.getAndAdd(hdr.num_seqnos) +1;
sendSeqnoResponse(sender, new_seqno, hdr.num_seqnos);
received_requests++;
break;
case SequencerHeader.RESPONSE:
Address coordinator=msg.getSrc();
if(view != null && !view.containsMember(coordinator)) {
log.error(local_addr + "%s: dropping RESPONSE from non-coordinator %s; view=%s", local_addr, coordinator, view);
return null;
}
long send_seqno=hdr.seqno;
for(int i=0; i < hdr.num_seqnos; i++) {
Message bcast_msg=fwd_queue.poll();
if(bcast_msg == null) {
log.error(Util.getMessage("Received%DSeqnosButFwdqueueIsEmpty"), hdr.num_seqnos);
break;
}
if(log.isTraceEnabled())
log.trace("%s: broadcasting %d", local_addr, send_seqno);
broadcast(bcast_msg, send_seqno++);
}
int num_reqs=0;
if((num_reqs=seqno_reqs.addAndGet(-hdr.num_seqnos)) > 0 && num_reqs > 0)
sendSeqnoRequest(num_reqs);
break;
case SequencerHeader.BCAST:
deliver(msg, hdr);
bcasts_received++;
break;
}
return null;
}
/* public void up(MessageBatch batch) { // todo: better impl: add seq messages into the table in 1 op
List> msgs=null;
for(Iterator it=batch.iterator(); it.hasNext();) {
final Message msg=it.next();
if(msg == null || msg.isFlagSet(Message.Flag.NO_TOTAL_ORDER) || msg.isFlagSet(Message.Flag.OOB))
continue;
SequencerHeader hdr=(SequencerHeader)msg.getHeader(id);
if(hdr == null)
continue;
it.remove(); // we have a header; remove the message from the batch, so it won't be passed up the stack
switch(hdr.type) {
case SequencerHeader.REQUEST:
case SequencerHeader.RESPONSE:
up(msg);
break;
case SequencerHeader.BCAST:
if(msgs == null)
msgs=new ArrayList>(batch.size());
msgs.add(new Tuple(hdr.seqno, msg));
break;
default:
log.error(Util.getMessage("HeaderTypeNotKnown"), local_addr, hdr.type);
}
}
if(msgs != null) {
Address sender=batch.sender();
if(sender == null) {
log.error(local_addr + ": sender is null, cannot deliver batch " + "::" + batch);
return;
}
final Table win=received_msgs;
System.out.println("<--B " + batch.sender() + "::" + batch);
win.add(msgs);
final AtomicBoolean processing=win.getProcessing();
if(processing.compareAndSet(false, true))
removeAndDeliver(processing, win, sender);
}
if(!batch.isEmpty())
up_prot.up(batch);
}*/
public void up(MessageBatch batch) {
Iterator it=batch.iterator();
while(it.hasNext()) {
Message msg=it.next();
if(msg.isFlagSet(Message.Flag.NO_TOTAL_ORDER) || msg.isFlagSet(Message.Flag.OOB) || msg.getHeader(id) == null)
continue;
it.remove();
// simplistic implementation
try {
up(msg);
}
catch(Throwable t) {
log.error(Util.getMessage("FailedPassingUpMessage"), t);
}
}
if(!batch.isEmpty())
up_prot.up(batch);
}
/* --------------------------------- Private Methods ----------------------------------- */
protected void handleViewChange(View v) {
List mbrs=v.getMembers();
if(mbrs.isEmpty()) return;
if(view == null || view.compareTo(v) < 0)
view=v;
else
return;
Address existing_coord=coord, new_coord=mbrs.get(0);
boolean coord_changed=!Objects.equals(existing_coord, new_coord);
if(coord_changed && new_coord != null) {
coord=new_coord;
// todo: if I'm the new coord, get the highest seqno from all members. If not, re-send my pending seqno reqs
}
if(new_coord != null)
is_coord=new_coord.equals(local_addr);
}
// If we're becoming coordinator, we need to handle TMP_VIEW as
// an immediate change of view. See JGRP-1452.
private void handleTmpView(View v) {
Address new_coord=v.getCoord();
if(new_coord != null && !new_coord.equals(coord) && local_addr != null && local_addr.equals(new_coord))
handleViewChange(v);
}
protected void sendSeqnoRequest(int num_seqnos) {
Address target=coord;
if(target == null)
return;
SequencerHeader hdr=new SequencerHeader(SequencerHeader.REQUEST, 0, num_seqnos);
Message forward_msg=new EmptyMessage(target).putHeader(this.id, hdr);
down_prot.down(forward_msg);
sent_requests++;
}
protected void sendSeqnoResponse(Address original_sender,long seqno, int num_seqnos) {
SequencerHeader hdr = new SequencerHeader(SequencerHeader.RESPONSE, seqno, num_seqnos);
Message ucast_msg = new EmptyMessage(original_sender).putHeader(this.id, hdr);
if (log.isTraceEnabled())
log.trace(local_addr + ": sending seqno response to " + original_sender + ":: new_seqno=" + seqno + ", num_seqnos=" + num_seqnos);
down_prot.down(ucast_msg);
sent_responses++;
}
protected void broadcast(final Message msg, long seqno) {
msg.putHeader(this.id, new SequencerHeader(SequencerHeader.BCAST, seqno));
if(log.isTraceEnabled())
log.trace(local_addr + ": broadcasting ::" + seqno);
down_prot.down(msg);
bcasts_sent++;
}
protected void deliver(Message msg, SequencerHeader hdr) {
Address sender=msg.getSrc();
if(sender == null) {
if(log.isErrorEnabled())
log.error(local_addr + ": sender is null, cannot deliver " + "::" + hdr.getSeqno());
return;
}
final Table win=received_msgs;
win.add(hdr.seqno, msg);
removeAndDeliver(win, sender);
}
protected void removeAndDeliver(Table win, Address sender) {
AtomicInteger adders=win.getAdders();
if(adders.getAndIncrement() != 0)
return;
final MessageBatch batch=new MessageBatch(win.size()).dest(local_addr).sender(sender).multicast(false);
Supplier batch_creator=() -> batch;
do {
try {
batch.reset();
win.removeMany(true, 0, null, batch_creator, BATCH_ACCUMULATOR);
}
catch(Throwable t) {
log.error("failed removing messages from table for " + sender, t);
}
if(!batch.isEmpty()) {
// batch is guaranteed to NOT contain any OOB messages as the drop_oob_msgs_filter removed them
deliverBatch(batch);
}
}
while(adders.decrementAndGet() != 0);
}
protected void deliverBatch(MessageBatch batch) {
try {
if(batch.isEmpty())
return;
if(log.isTraceEnabled()) {
Message first=batch.first(), last=batch.last();
StringBuilder sb=new StringBuilder(local_addr + ": delivering");
if(first != null && last != null) {
SequencerHeader hdr1=first.getHeader(id), hdr2=last.getHeader(id);
sb.append(" #").append(hdr1.seqno).append(" - #").append(hdr2.seqno);
}
sb.append(" (" + batch.size()).append(" messages)");
log.trace(sb);
}
up_prot.up(batch);
}
catch(Throwable t) {
log.error(Util.getMessage("FailedToDeliverMsg"), local_addr, "batch", batch, t);
}
}
/* ----------------------------- End of Private Methods -------------------------------- */
public static class SequencerHeader extends Header {
protected static final byte REQUEST = 1;
protected static final byte BCAST = 2;
protected static final byte RESPONSE = 3;
protected byte type;
protected long seqno;
protected int num_seqnos=1; // the number of seqnos requested (REQUEST) or returned (on a RESPONSE)
public SequencerHeader() {}
public SequencerHeader(byte type) {this.type=type;}
public SequencerHeader(byte type, long seqno) {
this(type, seqno, 1);
}
public SequencerHeader(byte type, long seqno, int num_seqnos) {
this(type);
this.seqno=seqno;
this.num_seqnos=num_seqnos;
}
public short getMagicId() {return 86;}
public Supplier create() {
return SequencerHeader::new;
}
public long getSeqno() {return seqno;}
public String toString() {
StringBuilder sb=new StringBuilder(64);
sb.append(printType());
if(seqno >= 0)
sb.append(" seqno=" + seqno);
if(num_seqnos > 1)
sb.append(", num_seqnos=" + num_seqnos);
return sb.toString();
}
protected final String printType() {
switch(type) {
case REQUEST: return "REQUEST";
case BCAST: return "BCAST";
case RESPONSE: return "RESPONSE";
default: return "n/a";
}
}
@Override
public void writeTo(DataOutput out) throws IOException {
out.writeByte(type);
Bits.writeLongCompressed(seqno, out);
out.writeShort(num_seqnos);
}
@Override
public void readFrom(DataInput in) throws IOException {
type=in.readByte();
seqno=Bits.readLongCompressed(in);
num_seqnos=in.readUnsignedShort();
}
// type + seqno + localSeqno + flush_ack
@Override
public int serializedSize() {
return Global.BYTE_SIZE + Bits.size(seqno) + Global.SHORT_SIZE;
}
}
}