oz.hadoop.yarn.api.net.ContainerDelegateImpl.java Source code

Introduction

Here is the source code for oz.hadoop.yarn.api.net.ContainerDelegateImpl.java

Source

/*
 * Copyright 2014 the original author or authors.
 *
 * 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 oz.hadoop.yarn.api.net;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.util.concurrent.Semaphore;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import oz.hadoop.yarn.api.YarnApplication;

/**
 * ContainerDelegate is a local proxy to the remote Application Container. 
 * It is created and returned in a form of an array during the invocation of {@link YarnApplication#launch()}
 * method essentially signifying that the Yarn application have been deployed successfully 
 * and interaction with Application Containers through simple messaging 
 * method can commence (see {@link #process(ByteBuffer, ReplyPostProcessor)).
 * 
 * @author Oleg Zhurakousky
 */
class ContainerDelegateImpl implements ContainerDelegate {
    private final Log logger = LogFactory.getLog(ContainerDelegateImpl.class);

    private final SelectionKey selectionKey;

    private final ApplicationContainerServerImpl clientServer;

    private final Semaphore executionGovernor;

    private final InetSocketAddress applicationContainerAddress;

    private volatile boolean suspended;

    /**
     * 
     * @param selectionKey
     * @param clientServer
     */
    ContainerDelegateImpl(SelectionKey selectionKey, ApplicationContainerServerImpl clientServer) {
        this.selectionKey = selectionKey;
        this.clientServer = clientServer;
        this.executionGovernor = new Semaphore(1);
        try {
            this.applicationContainerAddress = (InetSocketAddress) ((SocketChannel) this.selectionKey.channel())
                    .getLocalAddress();
        } catch (Exception e) {
            throw new IllegalArgumentException("Failed to get Applicatioin Container's address", e);
        }
    }

    /* (non-Javadoc)
     * @see oz.hadoop.yarn.api.net.ContainerDelegate#getHost()
     */
    @Override
    public InetSocketAddress getHost() {
        return this.applicationContainerAddress;
    }

    /* (non-Javadoc)
     * @see oz.hadoop.yarn.api.net.ContainerDelegate#exchange(java.nio.ByteBuffer)
     */
    @Override
    public void process(ByteBuffer data, ReplyPostProcessor replyPostProcessor) {
        try {
            if (!this.suspended) {
                this.executionGovernor.acquire();
                replyPostProcessor.setContainerDelegate(this);
                this.clientServer.process(selectionKey, data, replyPostProcessor);
            } else {
                logger.warn(
                        "This ContainerDelegate is suspended due to its imenent shutdown. No more processes would be accepted");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            logger.error("Interrupted while waiting for aquiring execution permit for " + this);
        }
    }

    /**
     * 
     */
    public void release() {
        this.executionGovernor.release();
    }

    /**
     * 
     */
    @Override
    public boolean available() {
        return this.executionGovernor.availablePermits() == 1;
    }

    /**
     * 
     */
    @Override
    public String toString() {
        return "CD:[" + this.getHost().getAddress().getHostAddress() + "]";
    }

    /**
     * 
     */
    @Override
    public void suspend() {
        this.suspended = true;
    }
}