package org.jgroups.protocols.pbcast;
import org.jgroups.*;
import org.jgroups.util.Digest;
import org.jgroups.util.Promise;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
/**
* @author Bela Ban
*/
public class ParticipantGmsImpl extends ServerGmsImpl {
private final List<Address> suspected_mbrs=new ArrayList<Address>(11);
private final Promise<Boolean> leave_promise=new Promise<Boolean>();
public ParticipantGmsImpl(GMS g) {
super(g);
}
public void init() throws Exception {
super.init();
suspected_mbrs.clear();
leave_promise.reset();
}
public void join(Address mbr, boolean useFlushIfPresent) {
wrongMethod("join");
}
public void joinWithStateTransfer(Address mbr,boolean useFlushIfPresent) {
wrongMethod("join");
}
/**
* Loop: determine coord. If coord is me --> handleLeave().
* Else send handleLeave() to coord until success
*/
public void leave(Address mbr) {
Address coord;
int max_tries=3;
leave_promise.reset();
if(mbr.equals(gms.local_addr))
leaving=true;
while((coord=gms.determineCoordinator()) != null && max_tries-- > 0) {
if(gms.local_addr.equals(coord)) { // I'm the coordinator
gms.becomeCoordinator();
// gms.getImpl().handleLeave(mbr, false); // regular leave
gms.getImpl().leave(mbr); // regular leave
return;
}
log.trace("%s: sending LEAVE request to %s", gms.local_addr, coord);
sendLeaveMessage(coord, mbr);
Boolean result=leave_promise.getResult(gms.leave_timeout);
if(result != null) {
log.trace("%s: got LEAVE response from %s", gms.local_addr, coord);
break;
}
}
gms.becomeClient();
}
/** 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
*
* @param join_rsp
*/
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 handleLeaveResponse() {
leave_promise.setResult(true); // unblocks thread waiting in leave()
}
public void suspect(Address mbr) {
Collection<Request> suspected=new LinkedHashSet<Request>(1);
suspected.add(new Request(Request.SUSPECT,mbr,true));
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<Request> requests) {
Collection<Address> suspectedMembers=new LinkedHashSet<Address>(requests.size());
for(Request req: requests)
if(req.type == Request.SUSPECT)
suspectedMembers.add(req.mbr);
if(suspectedMembers.isEmpty())
return;
for(Address mbr: suspectedMembers)
if(!suspected_mbrs.contains(mbr))
suspected_mbrs.add(mbr);
if(wouldIBeCoordinator()) {
log.debug("%s: members are %s, coord=%s: I'm the new coord !", gms.local_addr, gms.members, gms.local_addr);
gms.becomeCoordinator();
for(Address mbr: suspected_mbrs) {
gms.getViewHandler().add(new Request(Request.SUSPECT, mbr, true));
gms.ack_collector.suspect(mbr);
}
suspected_mbrs.clear();
}
}
/**
* If we are leaving, we have to wait for the view change (last msg in the current view) that
* excludes us before we can leave.
* @param new_view The view to be installed
* @param digest If view is a MergeView, digest contains the seqno digest of all members and has to
* be set by GMS
*/
public void handleViewChange(View new_view, Digest digest) {
suspected_mbrs.clear();
if(leaving && !new_view.containsMember(gms.local_addr)) // received a view in which I'm not member: ignore
return;
gms.installView(new_view, digest);
}
/* ---------------------------------- 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.
*/
boolean wouldIBeCoordinator() {
List<Address> mbrs=gms.computeNewMembership(gms.members.getMembers(), null, null, suspected_mbrs);
if(mbrs.size() < 1) return false;
Address new_coord=mbrs.get(0);
return gms.local_addr.equals(new_coord);
}
void sendLeaveMessage(Address coord, Address mbr) {
Message msg=new Message(coord).setFlag(Message.Flag.OOB)
.putHeader(gms.getId(), new GMS.GmsHeader(GMS.GmsHeader.LEAVE_REQ, mbr));
gms.getDownProtocol().down(new Event(Event.MSG, msg));
}
/* ------------------------------ End of Private Methods ------------------------------------ */
}