package org.jgroups.tests;
import org.jgroups.Global;
import org.jgroups.JChannel;
import org.jgroups.Message;
import org.jgroups.ReceiverAdapter;
import org.jgroups.conf.ClassConfigurator;
import org.jgroups.protocols.DISCARD;
import org.jgroups.protocols.pbcast.NAKACK2;
import org.jgroups.protocols.pbcast.NakAckHeader2;
import org.jgroups.protocols.pbcast.STABLE;
import org.jgroups.stack.Protocol;
import org.jgroups.stack.ProtocolStack;
import org.jgroups.util.Util;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;
import java.util.ArrayList;
import java.util.List;
/**
* Tests the last message dropped problem in NAKACK (see doc/design/varia2.txt)
* @author Bela Ban
*/
@Test(groups=Global.STACK_DEPENDENT,singleThreaded=true)
public class LastMessageDroppedTest extends ChannelTestBase {
protected JChannel a, b;
protected static final short NAKACK2_ID;
static {
NAKACK2_ID=ClassConfigurator.getProtocolId(NAKACK2.class);
}
@BeforeMethod void init() throws Exception {
a=createChannel(true, 2).name("A");
b=createChannel(a).name("B");
changeNAKACK2(a,b);
// it should take between 0 and 6s to retransmit the last missing msg. if dropped, may have to run multiple times
changeDesiredGossipTime(3000, a,b);
a.connect("LastMessageDroppedTest");
b.connect("LastMessageDroppedTest");
Util.waitUntilAllChannelsHaveSameView(10000, 500, a, b);
}
@AfterMethod void cleanup() {
Util.close(b,a);
}
public void testLastMessageDropped() throws Exception {
DISCARD discard=new DISCARD();
a.getProtocolStack().insertProtocol(discard,ProtocolStack.Position.BELOW,NAKACK2.class);
MyReceiver receiver=new MyReceiver();
b.setReceiver(receiver);
a.send(null, 1);
a.send(null, 2);
discard.setDropDownMulticasts(1); // drop the next multicast
a.send(null, 3);
List<Integer> list=receiver.getMsgs();
for(int i=0; i < 20 && list.size() < 3; i++) {
System.out.println("list=" + list);
Util.sleep(1000);
}
System.out.println("list=" + list);
assert list.size() == 3 : "list=" + list;
}
/**
* Tests the case where the last message is dropped, and the ensuing LAST_SEQNO message is also dropped. STABLE with
* a timeout of 5s should make sure that B eventually does get message 3.
*/
public void testLastMessageAndLastSeqnoDropped() throws Exception {
DISCARD discard=new DISCARD();
ProtocolStack stack=a.getProtocolStack();
stack.insertProtocol(discard,ProtocolStack.Position.BELOW,NAKACK2.class);
MyReceiver receiver=new MyReceiver();
b.setReceiver(receiver);
a.send(null, 1);
a.send(null, 2);
discard.setDropDownMulticasts(1); // drop the next multicast
stack.insertProtocol(new LastSeqnoDropper(1), ProtocolStack.Position.BELOW, NAKACK2.class);
a.send(null, 3);
List<Integer> list=receiver.getMsgs();
for(int i=0; i < 20 && list.size() < 3; i++) {
System.out.println("list=" + list);
Util.sleep(1000);
}
System.out.println("list=" + list);
assert list.size() == 3 : "list=" + list;
}
protected static void changeNAKACK2(JChannel ... channels) {
for(JChannel ch: channels) {
NAKACK2 nak=ch.getProtocolStack().findProtocol(NAKACK2.class);
nak.setResendLastSeqno(true);
nak.setResendLastSeqnoMaxTimes(1);
}
}
protected static void changeDesiredGossipTime(long avg_desired_gossip, JChannel ... channels) {
for(JChannel ch: channels) {
STABLE stable=ch.getProtocolStack().findProtocol(STABLE.class);
stable.setDesiredAverageGossip(avg_desired_gossip);
}
}
/** Drop {@link org.jgroups.protocols.pbcast.NakAckHeader2#HIGHEST_SEQNO} headers, needs to be inserted below NAKACK2 */
protected static class LastSeqnoDropper extends Protocol {
protected final int num_times; // how many times should we drop HIGHEST_SEQNO messages
protected int count;
public LastSeqnoDropper(int num_times) {
this.num_times=num_times;
}
public Object down(Message msg) {
NakAckHeader2 hdr=msg.getHeader(NAKACK2_ID);
if(hdr != null && count < num_times) {
count++;
return null;
}
return down_prot.down(msg);
}
}
protected static class MyReceiver extends ReceiverAdapter {
private final List<Integer> msgs=new ArrayList<>(3);
public List<Integer> getMsgs() {
return msgs;
}
public void receive(Message msg) {
msgs.add(msg.getObject());
}
}
}