org.jgroups.protocols.relay.Topology Maven / Gradle / Ivy

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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging 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.relay;

import org.jgroups.Address;
import org.jgroups.EmptyMessage;
import org.jgroups.Message;
import org.jgroups.View;
import org.jgroups.annotations.ManagedOperation;
import org.jgroups.annotations.Property;

import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.BiConsumer;

/**
 * Provides a cache of all sites and their members (addresses, IP addresses, site masters etc) in a network of
 * autonomous sites. The cache is an approximation, and is refreshed on reception of {@link RelayHeader#SITES_UP}
 * or {@link RelayHeader#SITES_DOWN} notifications. A refresh can also be triggered programmatically.
 * 

 * Used as a component in {@link RELAY2} and {@link RELAY3}.
 * @author Bela Ban
 * @since  5.2.15
 */
public class Topology {
    protected final RELAY             relay;
    protected final Map  cache=new ConcurrentHashMap<>(); // cache of sites and members
    protected BiConsumer view_handler;
    @Property(description="When true, members joining or leaving any site in the network are triggering the " +
      "view handler callback")
    protected boolean                 global_views=true; // might be set to false by default in the future

    public Topology(RELAY relay) {
        this.relay=Objects.requireNonNull(relay);
    }

    public Map cache()                {return cache;}
    public boolean          globalViews()          {return global_views;}
    public Topology         globalViews(boolean b) {global_views=b; return this;}

    /**
     * Sets a view handler
     * @param c The view handler. Arguments are the site and the {@link View} of that site)
     */
    public Topology setViewHandler(BiConsumer c) {
        view_handler=c; return this;}


    @ManagedOperation(description="Fetches information (site, address, IP address) from all members")
    public Topology refresh() {
        return refresh(null);
    }

    /**
     * Refreshes the topology for a given site.
     * @param site The site. If null, all sites will be refreshed.
     */
    @ManagedOperation(description="Fetches information (site, address, IP address) from all members of a given site")
    public Topology refresh(String site) {
        return refresh(site, false);
    }

    @ManagedOperation(description="Fetches the topology information for a given site")
    public Topology refresh(String site, boolean return_entire_cache) {
        Address dest=new SiteMaster(site); // sent to all site masters if site == null
        RelayHeader hdr=new RelayHeader(RelayHeader.TOPO_REQ)
          .setFinalDestination(dest).setOriginalSender(relay.getAddress())
          .returnEntireCache(return_entire_cache);
        Message topo_req=new EmptyMessage(dest).putHeader(relay.getId(), hdr);
        relay.down(topo_req);
        return this;
    }

    @ManagedOperation(description="Prints the cache information about all members")
    public String print() {
        return print(null);
    }

    /**
     * Dumps the members for a given site, or all sites
     * @param site The site name. Dumps all sites if null
     * @return A string of all sites and their members
     */
    @ManagedOperation(description="Prints the cache information about all members")
    public String print(String site) {
        if(site != null)
            return dumpSite(site);
        StringBuilder sb=new StringBuilder();
        for(Map.Entry e: cache.entrySet()) {
            sb.append(dumpSite(e.getKey())).append("\n");
        }
        return sb.toString();
    }

    public Topology removeAll(Collection sites) {
        if(sites == null)
            cache.keySet().clear();
        else
            cache.keySet().removeAll(sites);
        return this;
    }

    @Override
    public String toString() {
        return String.format("%d sites", cache.size());
    }

    protected String dumpSite(String site) {
        View view=cache.get(site);
        if(view == null)
            return String.format("%s: no view found for site %s", relay.getAddress(), site);
        return String.format("%s: %s", site, view);
    }

    /** Called when a response has been received. Updates the internal cache */
    protected void put(String site, View v) {
        View existing=cache.get(site);
        if(!Objects.equals(existing, v)) {
            cache.put(site, v);
            if(view_handler != null)
                view_handler.accept(site, v);
        }
    }

}