apps/vtn/sfcmgr/src/main/java/org/onosproject/sfc/manager/NshSpiIdGenerators.java

/*
 * Copyright 2015 Open Networking Laboratory
 *
 * 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 org.onosproject.sfc.manager;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Unique NSH SPI Id generator for NSH header.
 */
public final class NshSpiIdGenerators {

    private static final AtomicInteger NSH_SPI_ID_GEN = new AtomicInteger();
    private static final int MAX_NSH_SPI_ID = 0x7FFFFFFF;
    private static int nshSpiId;

    /**
     * Default constructor.
     */
    private NshSpiIdGenerators() {
    }

    /**
     * Get the next NSH SPI id.
     *
     * @return NSH SPI id
     */
    public static int create() {
        do {
            if (nshSpiId >= MAX_NSH_SPI_ID) {
                if (NSH_SPI_ID_GEN.get() >= MAX_NSH_SPI_ID) {
                    NSH_SPI_ID_GEN.set(0);
                }
            }
            nshSpiId = NSH_SPI_ID_GEN.incrementAndGet();
        } while (nshSpiId > MAX_NSH_SPI_ID);
        return nshSpiId;
    }
}