/*
 * Distributor.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>Distributor</code> object is used to execute operations that have
 * an interested I/O event ready. This acts much like a scheduler would in that
 * it delays the execution of the operations until such time as the associated
 * <code>SelectableChannel</code> has an interested I/O event ready.
 * <p>
 * This distributor has two modes, one mode is used to cancel the channel once
 * an I/O event has occurred. This means that the channel is removed from the
 * <code>Selector</code> so that the selector does not break when asked to
 * select again. Canceling the channel is useful when the operation execution
 * may not fully read the payload or when the operation takes a significant
 * amount of time.
 * 
 * @see org.simpleframework.transport.reactor.ActionDistributor
 */
interface Distributor {

    /**
     * This is used to process the <code>Operation</code> object. This will wake
     * up the selector if it is currently blocked selecting and register the
     * operations associated channel. Once the selector is awake it will acquire
     * the operation from the queue and register the associated
     * <code>SelectableChannel</code> for selection. The operation will then be
     * executed when the channel is ready for the interested I/O events.
     * 
     * @param task
     *            this is the task that is scheduled for distribution
     * @param require
     *            this is the bit-mask value for interested events
     */
    void process(Operation task, int require) throws IOException;

    /**
     * This is used to close the distributor such that it cancels all of the
     * registered channels and closes down the selector. This is used when the
     * distributor is no longer required, after the close further attempts to
     * process operations will fail.
     */
    void close() throws IOException;
}