org.jgroups.protocols.pbcast.ClientGmsImpl 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).
package org.jgroups.protocols.pbcast;
import org.jgroups.Address;
import org.jgroups.Event;
import org.jgroups.Message;
import org.jgroups.View;
import org.jgroups.protocols.PingData;
import org.jgroups.util.Digest;
import org.jgroups.util.Promise;
import org.jgroups.util.Responses;
import org.jgroups.util.Util;
import java.util.*;
/**
* Client part of GMS. Whenever a new member wants to join a group, it starts in the CLIENT role.
* No multicasts to the group will be received and processed until the member has been joined and
* turned into a SERVER (either coordinator or participant, mostly just participant). This class
* only implements Join (called by clients who want to join a certain group, and
* ViewChange which is called by the coordinator that was contacted by this client, to
* tell the client what its initial membership is.
* @author Bela Ban
* @version $Revision: 1.78 $
*/
public class ClientGmsImpl extends GmsImpl {
protected final Promise join_promise=new Promise<>();
public ClientGmsImpl(GMS g) {
super(g);
}
public void init() throws Exception {
super.init();
join_promise.reset();
}
public void join(Address address,boolean useFlushIfPresent) {
joinInternal(address, false,useFlushIfPresent);
}
public void joinWithStateTransfer(Address local_addr, boolean useFlushIfPresent) {
joinInternal(local_addr,true,useFlushIfPresent);
}
/**
* Joins this process to a group. Determines the coordinator and sends a
* unicast handleJoin() message to it. The coordinator returns a JoinRsp and
* then broadcasts the new view, which contains a message digest and the
* current membership (including the joiner). The joiner is then supposed to
* install the new view and the digest and starts accepting mcast messages.
* Previous mcast messages were discarded (this is done in PBCAST).
*
* If successful, impl is changed to an instance of ParticipantGmsImpl.
* Otherwise, we continue trying to send join() messages to the coordinator,
* until we succeed (or there is no member in the group. In this case, we
* create our own singleton group).
*
* When GMS.disable_initial_coord is set to true, then we won't become
* coordinator on receiving an initial membership of 0, but instead will
* retry (forever) until we get an initial membership of > 0.
*
* @param mbr Our own address (assigned through SET_LOCAL_ADDRESS)
*/
protected void joinInternal(Address mbr, boolean joinWithStateTransfer, boolean useFlushIfPresent) {
long join_attempts=0;
leaving=false;
join_promise.reset();
while(!leaving) {
if(installViewIfValidJoinRsp(join_promise, false))
return;
long start=System.currentTimeMillis();
Responses responses=(Responses)gms.getDownProtocol().down(Event.FIND_INITIAL_MBRS_EVT);
// Sept 2008 (bela): break if we got a belated JoinRsp (https://jira.jboss.org/jira/browse/JGRP-687)
if(installViewIfValidJoinRsp(join_promise, false))
return;
responses.waitFor(gms.join_timeout);
responses.done();
long diff=System.currentTimeMillis() - start;
if(responses.isEmpty()) {
log.trace("%s: no members discovered after %d ms: creating cluster as first member", gms.local_addr, diff);
becomeSingletonMember(mbr);
return;
}
log.trace("%s: discovery took %d ms, members: %s", gms.local_addr, diff, responses);
List
coords=getCoords(responses);
// We didn't get any coord responses; all responses were clients. If I'm the first of the sorted clients
// I'll become coordinator. The others will wait and then retry the discovery and join process
if(coords == null) { // e.g. because we have all clients only
if(firstOfAllClients(mbr, responses))
return;
continue;
}
if(coords.size() > 1) {
log.debug("%s: found multiple coords: %s", gms.local_addr, coords);
Collections.shuffle(coords); // so the code below doesn't always pick the same coord
}
join_attempts++;
for(Address coord: coords) {
log.debug("%s: sending JOIN(%s) to %s", gms.local_addr, mbr, coord);
sendJoinMessage(coord, mbr, joinWithStateTransfer, useFlushIfPresent);
if(installViewIfValidJoinRsp(join_promise, true))
return;
log.warn("%s: JOIN(%s) sent to %s timed out (after %d ms), on try %d",
gms.local_addr, mbr, coord, gms.join_timeout, join_attempts);
}
if(gms.max_join_attempts != 0 && join_attempts >= gms.max_join_attempts) {
log.warn("%s: too many JOIN attempts (%d): becoming singleton", gms.local_addr, join_attempts);
becomeSingletonMember(mbr);
return;
}
}
}
public void leave(Address mbr) {
leaving=true;
wrongMethod("leave");
}
public void handleJoinResponse(JoinRsp join_rsp) {
join_promise.setResult(join_rsp); // will wake up join() method
}
/* --------------------------- Private Methods ------------------------------------ */
// Installs a new view and sends an ack if (1) the join rsp is not null, (2) it is valid and (3) the view
// installation is successful. If true is returned, the JOIN process can be terminated, else it needs to
// go through discovery and JOIN-REQ again in a next iteration
protected boolean installViewIfValidJoinRsp(final Promise join_promise, boolean block_for_rsp) {
boolean success=false;
JoinRsp rsp=null;
try {
if(join_promise.hasResult())
rsp=join_promise.getResult(1, true);
else if(block_for_rsp)
rsp=join_promise.getResult(gms.join_timeout, true);
return success=rsp != null && isJoinResponseValid(rsp) && installView(rsp.getView(), rsp.getDigest());
}
finally {
if(success)
sendViewAck(rsp.getView().getCreator());
}
}
/** Handles the case where no coord responses were received. Returns true if we became the coord
* (caller needs to terminate the join() call), or false when the caller needs to continue */
protected boolean firstOfAllClients(final Address joiner, final Responses rsps) {
log.trace("%s: could not determine coordinator from rsps %s", gms.local_addr, rsps);
// so the member to become singleton member (and thus coord) is the first of all clients
SortedSet clients=new TreeSet<>();
clients.add(joiner); // add myself again (was removed by findInitialMembers())
for(PingData response: rsps)
clients.add(response.getAddress());
log.trace("%s: nodes to choose new coord from are: %s", gms.local_addr, clients);
Address new_coord=clients.first();
if(new_coord.equals(joiner)) {
log.trace("%s: I (%s) am the first of the nodes, will become coordinator", gms.local_addr, joiner);
becomeSingletonMember(joiner);
return true;
}
log.trace("%s: I (%s) am not the first of the nodes, waiting for another client to become coordinator",
gms.local_addr, joiner);
Util.sleep(500);
return false;
}
protected boolean isJoinResponseValid(final JoinRsp rsp) {
if(rsp.getFailReason() != null)
throw new SecurityException(rsp.getFailReason());
Digest tmp_digest=rsp.getDigest();
if(tmp_digest == null || tmp_digest.capacity() == 0) {
log.warn("%s: digest is empty: digest=%s", gms.local_addr, rsp.getDigest());
return false;
}
if(!tmp_digest.contains(gms.local_addr)) {
log.error("%s: digest in JOIN_RSP does not contain myself; join response: %s", gms.local_addr, rsp);
return false;
}
if(rsp.getView() == null) {
log.error("%s: JoinRsp has a null view, skipping it", gms.local_addr);
return false;
}
return true;
}
/**
* Called by join(). Installs the view returned by calling Coord.handleJoin() and becomes coordinator.
*/
private boolean installView(View new_view, Digest digest) {
if(!new_view.containsMember(gms.local_addr)) {
log.error("%s: I'm not member of %s, will not install view", gms.local_addr, new_view);
return false;
}
gms.installView(new_view, digest);
if(gms.impl == null || gms.impl instanceof ClientGmsImpl) // installView() should have set the role (impl)
gms.becomeParticipant();
gms.getUpProtocol().up(new Event(Event.BECOME_SERVER));
gms.getDownProtocol().down(new Event(Event.BECOME_SERVER));
return true;
}
protected static String print(List rsps) {
StringBuilder sb=new StringBuilder();
for(PingData rsp: rsps)
sb.append(rsp.getAddress() + " ");
return sb.toString();
}
protected static String print(Responses rsps) {
StringBuilder sb=new StringBuilder();
for(PingData rsp: rsps)
sb.append(rsp.getAddress() + " ");
return sb.toString();
}
void sendJoinMessage(Address coord, Address mbr,boolean joinWithTransfer, boolean useFlushIfPresent) {
Message msg=new Message(coord).setFlag(Message.Flag.OOB, Message.Flag.INTERNAL);
GMS.GmsHeader hdr=joinWithTransfer? new GMS.GmsHeader(GMS.GmsHeader.JOIN_REQ_WITH_STATE_TRANSFER, mbr,useFlushIfPresent)
: new GMS.GmsHeader(GMS.GmsHeader.JOIN_REQ, mbr,useFlushIfPresent);
msg.putHeader(gms.getId(), hdr);
gms.getDownProtocol().down(new Event(Event.MSG, msg));
}
void sendViewAck(Address coord) {
Message view_ack=new Message(coord).setFlag(Message.Flag.OOB, Message.Flag.INTERNAL)
.putHeader(gms.getId(), new GMS.GmsHeader(GMS.GmsHeader.VIEW_ACK));
gms.getDownProtocol().down(new Event(Event.MSG, view_ack)); // send VIEW_ACK to sender of view
}
/** Returns all members whose PingData is flagged as coordinator */
private static List getCoords(Iterable mbrs) {
if(mbrs == null)
return null;
List coords=null;
for(PingData mbr: mbrs) {
if(mbr.isCoord()) {
if(coords == null)
coords=new ArrayList<>();
if(!coords.contains(mbr.getAddress()))
coords.add(mbr.getAddress());
}
}
return coords;
}
void becomeSingletonMember(Address mbr) {
View new_view=View.create(mbr, 0, mbr); // create singleton view with mbr as only member
// set the initial digest (since I'm the first member)
Digest initial_digest=new Digest(mbr, 0, 0);
gms.installView(new_view, initial_digest);
gms.becomeCoordinator(); // not really necessary - installView() should do it
gms.getUpProtocol().up(new Event(Event.BECOME_SERVER));
gms.getDownProtocol().down(new Event(Event.BECOME_SERVER));
log.debug("%s: created cluster (first member). My view is %s, impl is %s",
gms.getLocalAddress(), gms.getViewId(), gms.getImpl().getClass().getName());
}
}