DirectReactor.java

/*
 * DirectReactor.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;
import java.util.concurrent.Executor;

import org.simpleframework.util.thread.DirectExecutor;

/**
 * The <code>DirectReactor</code> object is used to execute the ready operations
 * of within a single synchronous thread. This is used when the I/O operations
 * to be performed do not require much time to execute and so will not block the
 * execution thread.
 * 
 * @author Niall Gallagher
 */
public class DirectReactor implements Reactor {

    /**
     * This is used to distribute the ready operations for execution.
     */
    private final Distributor exchange;

    /**
     * This is used to execute the operations that ready to run.
     */
    private final Executor executor;

    /**
     * Constructor for the <code>DirectReactor</code> object. This is used to
     * create a reactor that does not require thread pooling to execute the
     * ready operations. All I/O operations are run in the selection thread and
     * should complete quickly.
     */
    public DirectReactor() throws IOException {
        this(false);
    }

    /**
     * Constructor for the <code>DirectReactor</code> object. This is used to
     * create a reactor that does not require thread pooling to execute the
     * ready operations. All I/O operations are run in the selection thread and
     * should complete quickly.
     * 
     * @param cancel
     *            determines the selection key should be canceled
     */
    public DirectReactor(boolean cancel) throws IOException {
        this.executor = new DirectExecutor();
        this.exchange = new ActionDistributor(this.executor, cancel);
    }

    /**
     * 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
     */
    @Override
    public void process(Operation task) throws IOException {
        this.executor.execute(task);
    }

    /**
     * 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 bit-mask value for interested events
     */
    @Override
    public void process(Operation task, int require) throws IOException {
        this.exchange.process(task, require);
    }

    /**
     * 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 graceful stop.
     */
    @Override
    public void stop() throws IOException {
        this.exchange.close();
    }
}