001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.nio.reactor;
029
030import java.io.IOException;
031
032/**
033 * HttpCore NIO is based on the Reactor pattern as described by Doug Lea.
034 * The purpose of I/O reactors is to react to I/O events and to dispatch event
035 * notifications to individual I/O sessions. The main idea of I/O reactor
036 * pattern is to break away from the one thread per connection model imposed
037 * by the classic blocking I/O model.
038 * <p>
039 * The IOReactor interface represents an abstract object implementing
040 * the Reactor pattern.
041 * <p>
042 * I/O reactors usually employ a small number of dispatch threads (often as
043 * few as one) to dispatch I/O event notifications to a much greater number
044 * (often as many as several thousands) of I/O sessions or connections. It is
045 * generally recommended to have one dispatch thread per CPU core.
046 *
047 * @since 4.0
048 */
049public interface IOReactor {
050
051    /**
052     * Returns the current status of the reactor.
053     *
054     * @return reactor status.
055     */
056    IOReactorStatus getStatus();
057
058    /**
059     * Starts the reactor and initiates the dispatch of I/O event notifications
060     * to the given {@link IOEventDispatch}.
061     *
062     * @param eventDispatch the I/O event dispatch.
063     * @throws IOException in case of an I/O error.
064     */
065    void execute(IOEventDispatch eventDispatch)
066        throws IOException;
067
068    /**
069     * Initiates shutdown of the reactor and blocks approximately for the given
070     * period of time in milliseconds waiting for the reactor to terminate all
071     * active connections, to shut down itself and to release system resources
072     * it currently holds.
073     *
074     * @param waitMs wait time in milliseconds.
075     * @throws IOException in case of an I/O error.
076     */
077    void shutdown(long waitMs)
078        throws IOException;
079
080    /**
081     * Initiates shutdown of the reactor and blocks for a default period of
082     * time waiting for the reactor to terminate all active connections, to shut
083     * down itself and to release system resources it currently holds. It is
084     * up to individual implementations to decide for how long this method can
085     * remain blocked.
086     *
087     * @throws IOException in case of an I/O error.
088     */
089    void shutdown()
090        throws IOException;
091
092}