org.zodiac.loadbalancer.ribbon.rule.DiscoveryEnabledRule Maven / Gradle / Ivy

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package org.zodiac.loadbalancer.ribbon.rule;

import org.zodiac.loadbalancer.ribbon.predicate.DiscoveryEnabledPredicate;
import org.zodiac.sdk.toolkit.util.AssertUtil;

import com.netflix.loadbalancer.AvailabilityPredicate;
import com.netflix.loadbalancer.CompositePredicate;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.PredicateBasedRule;
import com.netflix.loadbalancer.Server;

import java.util.List;

public abstract class DiscoveryEnabledRule extends PredicateBasedRule {

    private final CompositePredicate predicate;

    public DiscoveryEnabledRule(DiscoveryEnabledPredicate discoveryEnabledPredicate) {
        AssertUtil.notNull(discoveryEnabledPredicate, "Parameter 'discoveryEnabledPredicate' can't be null");
        this.predicate = createCompositePredicate(discoveryEnabledPredicate, new AvailabilityPredicate(this, null));
    }

    @Override
    public CompositePredicate getPredicate() {
        return predicate;
    }

    @Override
    public Server choose(Object key) {
        ILoadBalancer lb = getLoadBalancer();

        List allServers = lb.getAllServers();
        /*过滤服务列表。*/
        List serverList = filterServers(allServers);

        return getPredicate().chooseRoundRobinAfterFiltering(serverList, key).orNull();
    }

    /**
     * 过滤服务。
     *
     * @param serverList 服务列表
     * @return 服务列表
     */
    public abstract List filterServers(List serverList);

    private CompositePredicate createCompositePredicate(DiscoveryEnabledPredicate discoveryEnabledPredicate,
        AvailabilityPredicate availabilityPredicate) {
        CompositePredicate.Builder builder =
            CompositePredicate.withPredicates(discoveryEnabledPredicate, availabilityPredicate);
        return builder.build();
    }

}