/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.dubbo.rpc.protocol;

import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.rpc.Exporter;
import org.apache.dubbo.rpc.Invoker;

/**
 * AbstractExporter.
 */
public abstract class AbstractExporter<T> implements Exporter<T> {

    protected final Logger logger = LoggerFactory.getLogger(getClass());

    private final Invoker<T> invoker;

    private volatile boolean unexported = false;

    public AbstractExporter(Invoker<T> invoker) {
        if (invoker == null) {
            throw new IllegalStateException("service invoker == null");
        }
        if (invoker.getInterface() == null) {
            throw new IllegalStateException("service type == null");
        }
        if (invoker.getUrl() == null) {
            throw new IllegalStateException("service url == null");
        }
        this.invoker = invoker;
    }

    @Override
    public Invoker<T> getInvoker() {
        return invoker;
    }

    @Override
    final public void unexport() {
        if (unexported) {
            return;
        }
        unexported = true;
        getInvoker().destroy();
        afterUnExport();
    }

    /**
     * subclasses need to override this method to destroy resources.
     */
    public void afterUnExport() {
    }

    @Override
    public String toString() {
        return getInvoker().toString();
    }

}
