/*
 * Reactor.java February 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * 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 org.simpleframework.transport.reactor;

import java.io.IOException;

/**
 * The <code>Reactor</code> interface is used to describe an object that is used
 * to schedule asynchronous I/O operations. An operation is performed by handing
 * it to the reactor, which will determine if an interested event has occurred.
 * This allows the operation to perform the task in a manner that does not
 * block.
 * <p>
 * Implementing an <code>Operation</code> object requires that the operation
 * itself is aware of the I/O task it is performing. For example, if the
 * operation is concerned with reading data from the underlying channel then the
 * operation should perform the read, if there is more data required then that
 * operation to register with the reactor again to receive further
 * notifications.
 * 
 * @author Niall Gallagher
 * 
 * @see org.simpleframework.transport.reactor.Operation
 */
public interface Reactor {

    /**
     * This method is used to execute the provided operation without the need to
     * specifically check for I/O events. This is used if the operation knows
     * that the <code>SelectableChannel</code> is ready, or if the I/O operation
     * can be performed without knowing if the channel is ready. Typically this
     * is an efficient means to perform a poll rather than a select on the
     * channel.
     * 
     * @param task
     *            this is the task to execute immediately
     */
    void process(Operation task) throws IOException;

    /**
     * This method is used to execute the provided operation when there is an
     * I/O event that task is interested in. This will used the operations
     * <code>SelectableChannel</code> object to determine the events that are
     * ready on the channel. If this reactor is interested in any of the ready
     * events then the task is executed.
     * 
     * @param task
     *            this is the task to execute on interested events
     * @param require
     *            this is the bitmask value for interested events
     */
    void process(Operation task, int require) throws IOException;

    /**
     * This is used to stop the reactor so that further requests to execute
     * operations does nothing. This will clean up all of the reactors resources
     * and unregister any operations that are currently awaiting execution. This
     * should be used to ensure any threads used by the reactor gracefully stop.
     */
    void stop() throws IOException;
}