/*
 * Copyright 2013 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.util;

/**
 * Collection of method to handle objects that may implement {@link ReferenceCounted}.
 */
public final class ReferenceCountUtil {

    /**
     * Try to call {@link ReferenceCounted#retain()} if the specified message implements {@link ReferenceCounted}.
     * If the specified message doesn't implement {@link ReferenceCounted}, this method does nothing.
     */
    @SuppressWarnings("unchecked")
    public static <T> T retain(T msg) {
        if (msg instanceof ReferenceCounted) {
            return (T) ((ReferenceCounted) msg).retain();
        }
        return msg;
    }

    /**
     * Try to call {@link ReferenceCounted#retain()} if the specified message implements {@link ReferenceCounted}.
     * If the specified message doesn't implement {@link ReferenceCounted}, this method does nothing.
     */
    @SuppressWarnings("unchecked")
    public static <T> T retain(T msg, int increment) {
        if (msg instanceof ReferenceCounted) {
            return (T) ((ReferenceCounted) msg).retain(increment);
        }
        return msg;
    }

    /**
     * Try to call {@link ReferenceCounted#release()} if the specified message implements {@link ReferenceCounted}.
     * If the specified message doesn't implement {@link ReferenceCounted}, this method does nothing.
     */
    public static boolean release(Object msg) {
        if (msg instanceof ReferenceCounted) {
            return ((ReferenceCounted) msg).release();
        }
        return false;
    }

    /**
     * Try to call {@link ReferenceCounted#release()} if the specified message implements {@link ReferenceCounted}.
     * If the specified message doesn't implement {@link ReferenceCounted}, this method does nothing.
     */
    public static boolean release(Object msg, int decrement) {
        if (msg instanceof ReferenceCounted) {
            return ((ReferenceCounted) msg).release(decrement);
        }
        return false;
    }

    private ReferenceCountUtil() { }
}