org.jgroups.protocols.VERIFY_SUSPECT2 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.GuardedBy;
import org.jgroups.annotations.MBean;
import org.jgroups.annotations.ManagedAttribute;
import org.jgroups.annotations.Property;
import org.jgroups.conf.AttributeType;
import org.jgroups.stack.Protocol;
import org.jgroups.util.DefaultThreadFactory;
import org.jgroups.util.MessageBatch;
import org.jgroups.util.Util;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.locks.LockSupport;
import java.util.function.Supplier;
import java.util.stream.Collectors;
/**
* Double-checks that a suspected member is really dead.
* Details: https://issues.redhat.com/browse/JGRP-2558
* Design: https://github.com/belaban/JGroups/blob/master/doc/design/VERIFY_SUSPECT2.txt
* @author Bela Ban
*/
@MBean(description="Double-checks suspicions reports")
public class VERIFY_SUSPECT2 extends Protocol implements Runnable {
@Property(description="Number of millis to wait for verification that a suspect is really dead (approximation)",
type=AttributeType.TIME)
protected long timeout=1000;
@Property(description="Number of verify heartbeats sent to a suspected member")
protected int num_msgs=1;
@Property(description="Send the I_AM_NOT_DEAD message back as a multicast rather than as multiple unicasts " +
"(default is false)")
protected boolean use_mcast_rsps;
protected final Set suspects=new HashSet<>(); // for suspects (no duplicates)
@ManagedAttribute(description="Is the verifying task is running?")
protected boolean running;
protected ExecutorService thread_pool; // single-threaded+queue, runs the task when suspects are added
@ManagedAttribute(description = "List of currently suspected members")
public synchronized String getSuspects() {return suspects.toString();}
public VERIFY_SUSPECT2() {
}
/* ------------------------------------------ Builder-like methods ------------------------------------------ */
public VERIFY_SUSPECT2 setTimeout(long timeout) {
this.timeout = timeout;
return this;
}
public long getTimeout() {
return timeout;
}
public Object down(Event evt) {
switch(evt.getType()) {
case Event.VIEW_CHANGE:
View v=evt.getArg();
synchronized(this) {
suspects.removeIf(e -> !v.containsMember(e.suspect));
}
break;
}
return down_prot.down(evt);
}
public Object up(Event evt) {
switch(evt.getType()) {
case Event.SUSPECT: // it all starts here ...
if(evt.arg() == null)
return null;
// need to copy if we get an unmodifiable collection (we do modify the collection)
Collection s=new ArrayList<>(evt.arg());
s.remove(local_addr); // ignoring suspect of self
verifySuspect(s);
return null; // don't pass up; we will decide later (after verification) whether to pass it up
}
return up_prot.up(evt);
}
public Object up(Message msg) {
VerifyHeader hdr=msg.getHeader(this.id);
if(hdr == null)
return up_prot.up(msg);
return handle(hdr);
}
public void up(MessageBatch batch) {
for(Iterator it=batch.iterator(); it.hasNext();) {
Message msg=it.next();
VerifyHeader hdr=msg.getHeader(id);
if(hdr != null) {
it.remove();
handle(hdr);
}
}
if(!batch.isEmpty())
up_prot.up(batch);
}
/**
* Started when a suspected member is added to suspects. Clears the bucket and sends the contents up the stack as
* SUSPECT events, then moves suspects from the queue to the bucket. Runs until the queue and bucket are both empty.
*/
public void run() {
List suspected_mbrs=new ArrayList<>();
while(running) {
long target_time=System.currentTimeMillis() + timeout;
do {
LockSupport.parkUntil(target_time);
}
while(System.currentTimeMillis() < target_time);
suspected_mbrs.clear();
synchronized(this) {
suspects.forEach(e -> {
if(e.target_time <= target_time)
suspected_mbrs.add(e.suspect);
});
suspects.removeIf(e -> e.target_time <= target_time);
}
if(!suspected_mbrs.isEmpty()) {
log.debug("%s: sending up SUSPECT(%s)", local_addr, suspected_mbrs);
up_prot.up(new Event(Event.SUSPECT, suspected_mbrs));
}
else {
synchronized(this) {
if(suspects.isEmpty()) {
running=false;
break;
}
}
}
}
}
/* --------------------------------- Private Methods ----------------------------------- */
protected Object handle(VerifyHeader hdr) {
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 EmptyMessage(target)
.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;
}
/**
* Sends ARE_YOU_DEAD message to suspected_mbr, wait for return or timeout
*/
protected void verifySuspect(Collection mbrs) {
if(mbrs == null || mbrs.isEmpty())
return;
if(addSuspects(mbrs)) {
startTask(); // 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 EmptyMessage(mbr)
.putHeader(this.id, new VerifyHeader(VerifyHeader.ARE_YOU_DEAD, local_addr));
down_prot.down(msg);
}
}
}
/**
* Adds suspected members to the suspect list. Returns true if a member is not present and the timer is not running.
* @param list The list of suspected members
* @return true if the timer needs to be started, or false otherwise
*/
protected synchronized boolean addSuspects(Collection list) {
if(list == null || list.isEmpty())
return false;
long target_time=getCurrentTimeMillis();
List tmp=list.stream().map(a -> new Entry(a, target_time)).collect(Collectors.toList());
return suspects.addAll(tmp);
}
protected synchronized boolean removeSuspect(Address suspect) {
return suspects.removeIf(e -> Objects.equals(e.suspect, suspect));
}
public void unsuspect(Address mbr) {
boolean removed=mbr != null && removeSuspect(mbr);
if(removed) {
log.trace("member %s was unsuspected", mbr);
down_prot.down(new Event(Event.UNSUSPECT, mbr));
up_prot.up(new Event(Event.UNSUSPECT, mbr));
}
}
protected synchronized void startTask() {
if(!running) {
running=true;
thread_pool.execute(this);
}
}
@GuardedBy("lock")
protected void stopThreadPool() {
if(thread_pool != null)
thread_pool.shutdown();
}
public void init() throws Exception {
super.init();
ThreadFactory f=new DefaultThreadFactory(this.getClass().getSimpleName() + ".Runner", true, true);
thread_pool=new ThreadPoolExecutor(0, 1, // max 1 thread, started each time a suspect is added
0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(), f);
}
public synchronized void stop() {
suspects.clear();
}
public void destroy() {
stopThreadPool();
synchronized(this) {
running=false;
}
super.destroy();
}
private static long getCurrentTimeMillis() {
return TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
}
/* ----------------------------- End of Private Methods -------------------------------- */
protected static class Entry implements Comparable {
protected final Address suspect;
protected final long target_time; // millis
public Entry(Address suspect, long target_time) {
this.suspect=suspect;
this.target_time=target_time;
}
public boolean equals(Object obj) {
if(!(obj instanceof Entry))
return false;
Entry other=(Entry)obj;
return Objects.equals(suspect, other.suspect);
}
public int hashCode() {
return suspect.hashCode();
}
public String toString() {
return String.format("%s (expires in %d ms)", suspect, expiry());
}
protected long expiry() {
return target_time - getCurrentTimeMillis();
}
public int compareTo(Entry o) {
return suspect.compareTo(o.suspect);
}
}
public static class VerifyHeader extends Header {
static final short ARE_YOU_DEAD=1; // 'from' is sender of verify msg
static final short I_AM_NOT_DEAD=2; // 'from' is suspected member
short type=ARE_YOU_DEAD;
Address from; // member who wants to verify that suspected_mbr is dead
public VerifyHeader() {
} // used for externalization
VerifyHeader(short type) {
this.type=type;
}
VerifyHeader(short type, Address from) {
this(type);
this.from=from;
}
public short getMagicId() {return 94;}
public Supplier create() {return VerifyHeader::new;}
public String toString() {
switch(type) {
case ARE_YOU_DEAD:
return "[ARE_YOU_DEAD]";
case I_AM_NOT_DEAD:
return "[I_AM_NOT_DEAD]";
default:
return "[unknown type (" + type + ")]";
}
}
@Override
public void writeTo(DataOutput out) throws IOException {
out.writeShort(type);
Util.writeAddress(from, out);
}
@Override
public void readFrom(DataInput in) throws IOException, ClassNotFoundException {
type=in.readShort();
from=Util.readAddress(in);
}
@Override
public int serializedSize() {
return Global.SHORT_SIZE + Util.size(from);
}
}
}