Java example source code file (DnsCacheEntry.java)

This example Java source code file (DnsCacheEntry.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

dnscacheentry, inetaddress, net, network, override, runnable, scheduledfuture, string, threading, threads, throwable, timeunit, unstableapi

The DnsCacheEntry.java Java example source code

/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project 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 io.netty.resolver.dns;

import static io.netty.util.internal.ObjectUtil.checkNotNull;

import io.netty.channel.EventLoop;
import io.netty.util.concurrent.ScheduledFuture;
import io.netty.util.internal.UnstableApi;

import java.net.InetAddress;
import java.util.concurrent.TimeUnit;

/**
 * Entry in {@link DnsCache}.
 */
@UnstableApi
public final class DnsCacheEntry {

    private final String hostname;
    private final InetAddress address;
    private final Throwable cause;
    private volatile ScheduledFuture<?> expirationFuture;

    public DnsCacheEntry(String hostname, InetAddress address) {
        this.hostname = checkNotNull(hostname, "hostname");
        this.address = checkNotNull(address, "address");
        cause = null;
    }

    public DnsCacheEntry(String hostname, Throwable cause) {
        this.hostname = checkNotNull(hostname, "hostname");
        this.cause = checkNotNull(cause, "cause");
        address = null;
    }

    public String hostname() {
        return hostname;
    }

    public InetAddress address() {
        return address;
    }

    public Throwable cause() {
        return cause;
    }

    void scheduleExpiration(EventLoop loop, Runnable task, long delay, TimeUnit unit) {
        assert expirationFuture == null: "expiration task scheduled already";
        expirationFuture = loop.schedule(task, delay, unit);
    }

    void cancelExpiration() {
        ScheduledFuture<?> expirationFuture = this.expirationFuture;
        if (expirationFuture != null) {
            expirationFuture.cancel(false);
        }
    }

    @Override
    public String toString() {
        if (cause != null) {
            return hostname + '/' + cause;
        } else {
            return address.toString();
        }
    }
}