com.github.cm.heclouds.adapter.mqttadapter.mqtt.MqttPacketId Maven / Gradle / Ivy

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/*
 * Copyright (C) 2018 Issey Yamakoshi
 *
 * 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 com.github.cm.heclouds.adapter.mqttadapter.mqtt;

import java.io.Serializable;
import java.util.concurrent.atomic.AtomicInteger;

public final class MqttPacketId implements Serializable {

    private static final long serialVersionUID = -1608711409506773103L;

    public static final int MIN_VALUE = 1;
    public static final int MAX_VALUE = 65535;

    private final AtomicInteger id;

    public MqttPacketId() {
        this(MIN_VALUE);
    }

    public MqttPacketId(int initialValue) {
        this.id = new AtomicInteger(requireValidPacketId(initialValue, "initialValue"));
    }

    public int get() {
        return id.get();
    }

    public int getAndIncrement() {
        int prev;
        int next;
        do {
            next = (prev = id.get()) >= MAX_VALUE ? MIN_VALUE : prev + 1;
        } while (!id.compareAndSet(prev, next));
        return prev;
    }

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

    public static boolean isValidPacketId(int id) {
        return id >= MIN_VALUE && id <= MAX_VALUE;
    }

    public static int requireValidPacketId(int id, String name) throws IllegalArgumentException {
        if (!isValidPacketId(id)) {
            throw new IllegalArgumentException(name + ": " + id + " (expected: 1–65535)");
        }
        return id;
    }
}