/*
 * Copyright (c) 2008-2014 MongoDB, Inc.
 *
 * 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.mongodb.binding;

/**
 * An interface for reference-counted objects.
 *
 * @since 3.0
 */
public interface ReferenceCounted {
    /**
     * Gets the current reference count, which starts at 0.
     *
     * @return the current count, which must be greater than or equal to 0
     */
    int getCount();

    /**
     * Retain an additional reference to this object.  All retained references must be released, or there will be a leak.
     *
     * @return this
     */
    ReferenceCounted retain();

    /**
     * Release a reference to this object.
     * @throws java.lang.IllegalStateException if the reference count is already 0
     */
    void release();
}