httpcore5/src/main/java/org/apache/hc/core5/reactor/IOReactor.java

/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
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 * <http://www.apache.org/>.
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package org.apache.hc.core5.reactor;

import org.apache.hc.core5.io.CloseMode;
import org.apache.hc.core5.io.ModalCloseable;
import org.apache.hc.core5.util.TimeValue;

/**
 * HttpCore NIO is based on the Reactor pattern as described by Doug Lea.
 * The purpose of I/O reactors is to react to I/O events and to dispatch event
 * notifications to individual I/O sessions. The main idea of I/O reactor
 * pattern is to break away from the one thread per connection model imposed
 * by the classic blocking I/O model.
 * <p>
 * The IOReactor interface represents an abstract object implementing
 * the Reactor pattern.
 * <p>
 * I/O reactors usually employ a small number of dispatch threads (often as
 * few as one) to dispatch I/O event notifications to a much greater number
 * (often as many as several thousands) of I/O sessions or connections. It is
 * generally recommended to have one dispatch thread per CPU core.
 *
 * @since 4.0
 */
public interface IOReactor extends ModalCloseable {

    /**
     * Shuts down the I/O reactor either gracefully or immediately.
     * During graceful shutdown individual I/O sessions should be
     * informed about imminent termination and be given a grace period
     * to complete the ongoing I/O sessions. During immediate shutdown
     * all ongoing I/O sessions get aborted immediately.
     */
    @Override
    void close(CloseMode closeMode);

    /**
     * Returns the current status of the reactor.
     *
     * @return reactor status.
     */
    IOReactorStatus getStatus();

    /**
     * Initiates shutdown of the reactor without blocking. The reactor is expected
     * to terminate all active connections, to shut down itself and to release
     * system resources it currently holds
     *
     * @since 5.0
     */
    void initiateShutdown();

    /**
     * Blocks for the given period of time in milliseconds awaiting
     * the completion of the reactor shutdown.
     *
     * @param waitTime wait time.
     *
     * @since 5.0
     */
    void awaitShutdown(TimeValue waitTime) throws InterruptedException;

}