java source code of DiscoveryEnabledPredicate

/**
 * Copyright (c) 2015 the original author or authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.jmnarloch.spring.cloud.ribbon.predicate;

import com.netflix.loadbalancer.AbstractServerPredicate;
import com.netflix.loadbalancer.PredicateKey;
import com.netflix.niws.loadbalancer.DiscoveryEnabledServer;

import javax.annotation.Nullable;

/**
 * A template method predicate to be applied to service discovered server instances. The concreate implementation of
 * this class need to implement the {@link #apply(DiscoveryEnabledServer)} method.
 *
 * @author Jakub Narloch
 */
public abstract class DiscoveryEnabledPredicate extends AbstractServerPredicate {

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean apply(@Nullable PredicateKey input) {
        return input != null
                && input.getServer() instanceof DiscoveryEnabledServer
                && apply((DiscoveryEnabledServer) input.getServer());
    }

    /**
     * Returns whether the specific {@link DiscoveryEnabledServer} matches this predicate.
     *
     * @param server the discovered server
     * @return whether the server matches the predicate
     */
    protected abstract boolean apply(DiscoveryEnabledServer server);
}