org.jgroups.protocols.pbcast.ParticipantGmsImpl 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.pbcast;

import org.jgroups.*;
import org.jgroups.util.Digest;

import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;


/**
 * @author Bela Ban
 */
public class ParticipantGmsImpl extends ServerGmsImpl {
    private final Collection suspected_mbrs=new LinkedHashSet<>();


    public ParticipantGmsImpl(GMS g) {
        super(g);
    }


    public void init() throws Exception {
        super.init();
        suspected_mbrs.clear();
    }

    public void join(Address mbr, boolean useFlushIfPresent) {
        wrongMethod("join");
    }

    public void joinWithStateTransfer(Address mbr,boolean useFlushIfPresent) {
        wrongMethod("join");
    }


    public void leave() {
        try {
            leaver.leave();
        }
        finally {
            gms.initState();
        }
    }


    /** In case we get a different JOIN_RSP from a previous JOIN_REQ sent by us (as a client), we simply apply the
     * new view if it is greater than ours
     */
    @Override
    public void handleJoinResponse(JoinRsp join_rsp) {
        View v=join_rsp.getView();
        ViewId tmp_vid=v != null? v.getViewId() : null;
        ViewId my_view=gms.getViewId();
        if(tmp_vid != null && my_view != null && tmp_vid.compareToIDs(my_view) > 0) {
            Digest d=join_rsp.getDigest();
            gms.installView(v, d);
        }
    }



    public void suspect(Address mbr) {
        Collection suspected=new LinkedHashSet<>(1);
        suspected.add(new Request(Request.SUSPECT, mbr));
        handleMembershipChange(suspected);
    }


    /** Removes previously suspected member from list of currently suspected members */
    public void unsuspect(Address mbr) {
        if(mbr != null)
            suspected_mbrs.remove(mbr);
    }


    public void handleMembershipChange(Collection requests) {
        Collection leaving_mbrs=new LinkedHashSet<>(requests.size());
        requests.forEach(r -> {
            if(r.type == Request.SUSPECT)
                suspected_mbrs.add(r.mbr);
            else if(r.type == Request.LEAVE)
                leaving_mbrs.add(r.mbr);
        });

        if(suspected_mbrs.isEmpty() && leaving_mbrs.isEmpty())
            return;

        if(wouldIBeCoordinator(leaving_mbrs)) {
            log.debug("%s: members are %s, coord=%s: I'm the new coordinator", gms.getAddress(), gms.members, gms.getAddress());
            gms.becomeCoordinator();
            Collection leavingOrSuspectedMembers=new LinkedHashSet<>();
            leaving_mbrs.forEach(mbr -> leavingOrSuspectedMembers.add(new Request(Request.LEAVE, mbr)));
            suspected_mbrs.forEach(mbr -> {
                leavingOrSuspectedMembers.add(new Request(Request.SUSPECT, mbr));
                gms.ack_collector.suspect(mbr);
            });
            suspected_mbrs.clear();
            if(gms.isLeaving())
                leavingOrSuspectedMembers.add(new Request(Request.COORD_LEAVE));
            gms.getViewHandler().add(leavingOrSuspectedMembers);
        }
        else
            log.warn("%s: I'm not the coordinator (or next-in-line); dropping LEAVE request by %s",
                     gms.getAddress(), leaving_mbrs);
    }


    public void handleViewChange(View view, Digest digest) {
        suspected_mbrs.clear();
        super.handleViewChange(view, digest);
    }

    @Override protected void coordChanged(Address from, Address to) {
        super.coordChanged(from, to);
        leaver.coordChanged(to);
    }

    /* ---------------------------------- Private Methods --------------------------------------- */

    /**
     * Determines whether this member is the new coordinator given a list of suspected members.  This is
     * computed as follows: the list of currently suspected members (suspected_mbrs) is removed from the current
     * membership. If the first member of the resulting list is equals to the local_addr, then it is true,
     * otherwise false. Example: own address is B, current membership is {A, B, C, D}, suspected members are {A,
     * D}. The resulting list is {B, C}. The first member of {B, C} is B, which is equal to the
     * local_addr. Therefore, true is returned.
     */
    protected boolean wouldIBeCoordinator(Collection leaving_mbrs) {
        List mbrs=gms.computeNewMembership(gms.members.getMembers(), null, leaving_mbrs, suspected_mbrs);
        if(mbrs.isEmpty()) return false;
        Address new_coord=mbrs.get(0);
        return gms.getAddress().equals(new_coord);
    }


   /* protected void sendLeaveMessage(Address coord, Address mbr) {
        Message msg=new EmptyMessage(coord).setFlag(Message.Flag.OOB)
          .putHeader(gms.getId(), new GMS.GmsHeader(GMS.GmsHeader.LEAVE_REQ, mbr));
        gms.getDownProtocol().down(msg);
    }*/
    /* ------------------------------ End of Private Methods ------------------------------------ */

}