org.jgroups.protocols.relay.StickySiteMasterPicker 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 java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Picks a local site master or a route based on the sender and caches the decision. Next time, the same local site
 * master or route will be returned. If no route exists yet, a random local site master or route is picked.
 * @author Bela Ban
 * @since  5.3.1
 */
public class StickySiteMasterPicker extends RandomSiteMasterPicker {
    protected Map local_sm_cache=new ConcurrentHashMap<>();
    protected Map   route_cache=new ConcurrentHashMap<>();

    @Override
    public Address pickSiteMaster(List site_masters, Address original_sender) {
        if(original_sender == null)
            return super.pickSiteMaster(site_masters, original_sender);
        Address local_sm=local_sm_cache.get(original_sender);
        if(local_sm != null) {
            if(site_masters.contains(local_sm))
                return local_sm;
            local_sm_cache.remove(original_sender);
            local_sm=null;
        }

        // cache has no entry to original_sender or entry is stale
        local_sm=super.pickSiteMaster(site_masters, original_sender);
        Address existing=local_sm_cache.putIfAbsent(original_sender, local_sm);
        return existing != null? existing : local_sm;
    }

    @Override
    public Route pickRoute(String site, List routes, Address original_sender) {
        if(original_sender == null)
            return super.pickRoute(site, routes, original_sender);

        Route route=route_cache.get(original_sender);
        if(route != null) {
            if(routes.contains(route))
                return route;
            route_cache.remove(original_sender);
            route=null;
        }

        // cache has no entry to original_sender or entry is stale
        route=super.pickRoute(site, routes, original_sender);
        Route existing=route_cache.putIfAbsent(original_sender, route);
        return existing != null? existing : route;
    }
}