001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.core.write;
021
022import org.apache.mina.core.session.IoSession;
023
024/**
025 * Stores {@link WriteRequest}s which are queued to an {@link IoSession}.
026 * 
027 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
028 */
029public interface WriteRequestQueue {
030
031    /**
032     * Get the first request available in the queue for a session.
033     * @param session The session
034     * @return The first available request, if any.
035     */
036    WriteRequest poll(IoSession session);
037
038    /**
039     * Add a new WriteRequest to the session write's queue
040     * @param session The session
041     * @param writeRequest The writeRequest to add
042     */
043    void offer(IoSession session, WriteRequest writeRequest);
044
045    /**
046     * Tells if the WriteRequest queue is empty or not for a session
047     * @param session The session to check
048     * @return <tt>true</tt> if the writeRequest is empty
049     */
050    boolean isEmpty(IoSession session);
051
052    /**
053     * Removes all the requests from this session's queue.
054     * @param session The associated session
055     */
056    void clear(IoSession session);
057
058    /**
059     * Disposes any releases associated with the specified session.
060     * This method is invoked on disconnection.
061     * @param session The associated session
062     */
063    void dispose(IoSession session);
064
065    /**
066     * @return the number of objects currently stored in the queue.
067     */
068    int size();
069}