org.jgroups.protocols.INJECT_VIEW 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.Address;
import org.jgroups.View;
import org.jgroups.annotations.MBean;
import org.jgroups.annotations.ManagedOperation;
import org.jgroups.protocols.pbcast.GMS;
import org.jgroups.stack.Protocol;
import org.jgroups.util.NameCache;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Simple protocol to inject an arbitrary view on one or more cluster nodes.
 * INJECT_VIEW exposes a managed operation (injectView) capable of injecting a view by parsing the view state from a string.
 * The string format is A=A/B/C;B=B/C;C=C (where A,B,C are node names), this would inject view [A,B,C] with A as leader in node A,
 * view [B,C] with B as leader in node B and view [C] in node C.
 * In order to leverage the injection on multiple nodes at once use a tool like probe.sh
 * (https://github.com/belaban/JGroups/blob/master/tests/other/org/jgroups/tests/Probe.java)
 * @author Andrea Tarocchi
 * @author Ugo Landini
 * @since 4.0.10
 * @see GMS
 */
@MBean(description="Protocol to inject an arbitrary view in nodes")
public class INJECT_VIEW extends Protocol {

    public static final String NODE_VIEWS_SEPARATOR = ";";
    public static final String VIEW_SEPARATOR = "=";
    public static final String NAMES_SEPARATOR = "/";

    @ManagedOperation(description="Inject a view (example of view string format: A=A/B/C;B=B/C;C=C)")
    public synchronized void injectView(String newView) {
        try {
            log.info("Received request to inject view %s", newView);
            String[] perNode = newView.split(NODE_VIEWS_SEPARATOR);
            String thisNodeAddress = getProtocolStack().getChannel().getAddressAsString();

            for( String nodeView : perNode ){
                if( nodeView.startsWith(thisNodeAddress) ) {
                    log.info("[channel: %s] Injecting a new view: %s", thisNodeAddress, nodeView);

                    long viewId = getProtocolStack().getChannel().getView().getViewId().getId()+1;
                    List nodes = new ArrayList<>();

                    for( String nodeName : nodeView.split(VIEW_SEPARATOR)[1].split(NAMES_SEPARATOR) ){
                        for( Map.Entry entry : NameCache.getContents().entrySet() ) {
                            if( nodeName.equals(entry.getValue()) ){
                                log.debug("[channel: %s] Found name: <%s> for address: <%s>", entry.getValue(), entry.getKey().toString());
                                nodes.add( entry.getKey() );
                                break;
                            }
                        }
                    }

                    View view = new View( nodes.get(0), viewId, nodes);

                    GMS gms = getProtocolStack().findProtocol(GMS.class);
                    gms.installView(view);
                    log.info("[channel: %s] Injection finished of view: %s", thisNodeAddress, nodeView);
                }
            }
        }
        catch(Exception e) {
            log.warn(e.getMessage(), e);
        }
    }
}