OrElseEndpointGroup.java

/*
 * Copyright 2016 LINE Corporation
 *
 * LINE Corporation licenses this file to you 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 com.linecorp.armeria.client.endpoint;

import static java.util.Objects.requireNonNull;

import java.util.List;

import com.linecorp.armeria.client.Endpoint;
import com.linecorp.armeria.common.util.AbstractListenable;

final class OrElseEndpointGroup extends AbstractListenable<List<Endpoint>> implements EndpointGroup {
    private final EndpointGroup first;
    private final EndpointGroup second;

    OrElseEndpointGroup(EndpointGroup first, EndpointGroup second) {
        this.first = requireNonNull(first, "first");
        this.second = requireNonNull(second, "second");
        first.addListener(unused -> notifyListeners(endpoints()));
        second.addListener(unused -> notifyListeners(endpoints()));
    }

    @Override
    public List<Endpoint> endpoints() {
        List<Endpoint> endpoints = first.endpoints();
        if (!endpoints.isEmpty()) {
            return endpoints;
        }
        return second.endpoints();
    }
}