org.trpr.platform.runtime.impl.event.BootstrapProgressMonitor.java Source code

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Here is the source code for org.trpr.platform.runtime.impl.event.BootstrapProgressMonitor.java

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/*
 * Copyright 2012-2015, 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 org.trpr.platform.runtime.impl.event;

import org.trpr.platform.core.impl.event.PlatformApplicationEvent;
import org.trpr.platform.core.impl.logging.LogFactory;
import org.trpr.platform.core.spi.event.PlatformEventConsumer;
import org.trpr.platform.core.spi.logging.Logger;
import org.trpr.platform.model.event.PlatformEvent;
import org.trpr.platform.runtime.common.RuntimeConstants;
import org.springframework.context.ApplicationEvent;

/**
 * The <code>BootstrapProgressMonitor</code> is an implementation of the {@link PlatformEventConsumer} interface that listens and processes 
 * {@link PlatformEvent} that is of type {@link RuntimeConstants#BOOTSTRAPMONITOREDEVENT}. This class provides blocking semantics on the invoking 
 * thread if the bootstrap process is not completed. 
 * 
 * @author Regunath B
 * @version 1.0, 06/06/2012
 */

public class BootstrapProgressMonitor implements PlatformEventConsumer {

    /**
     * The Logger instance for this class
     */
    private static final Logger LOGGER = LogFactory.getLogger(BootstrapProgressMonitor.class);

    /** Constants to indicate possible states of this progress monitor*/
    private static final int BOOTSTRAP_IN_PROGRESS = 0;
    private static final int BOOTSTRAP_COMPLETE = 1;

    /** Place holder for storing the current state of bootstrap progress*/
    private volatile static int bootstrapState = BOOTSTRAP_IN_PROGRESS;

    /**
     * Checks the runtime state and makes the calling thread wait for bootstrap to complete.
     */
    public void waitForBootstrapComplete() {
        while (BootstrapProgressMonitor.bootstrapState == BootstrapProgressMonitor.BOOTSTRAP_IN_PROGRESS) {
            synchronized (BootstrapProgressMonitor.class) {
                try {
                    LOGGER.info(
                            "Bootstrap in progress. BootstrapProgressMonitor waiting to be notified on completion for thread : "
                                    + Thread.currentThread());
                    BootstrapProgressMonitor.class.wait();
                    LOGGER.info("Bootstrap completed. BootstrapProgressMonitor allowing thread to continue : "
                            + Thread.currentThread());
                } catch (InterruptedException e) {
                    // ignore this exception
                }
            }
        }
    }

    /**
     * Interface method implementation. Handles ApplicationEvent only of type {@link PlatformApplicationEvent} where the source is
     * {@link PlatformEvent} and of type {@link ServerConstants#BOOTSTRAPMONITOREDEVENT}. Wakes up any waiting threads that are awaiting
     * bootstrap completion. Also updates the internal bootstrap progress state maintained by this class
     * @see org.springframework.context.ApplicationListener#onApplicationEvent(org.springframework.context.ApplicationEvent)
     */
    public void onApplicationEvent(ApplicationEvent event) {
        if (event.getSource() instanceof PlatformEvent) {
            PlatformEvent platformEvent = (PlatformEvent) event.getSource();
            if (platformEvent.getEventType() != null
                    && platformEvent.getEventType().equalsIgnoreCase(RuntimeConstants.BOOTSTRAPMONITOREDEVENT)) {
                synchronized (BootstrapProgressMonitor.class) {
                    if (platformEvent.getEventStatus() != null && platformEvent.getEventStatus()
                            .equalsIgnoreCase(RuntimeConstants.BOOTSTRAP_START_STATE)) {
                        BootstrapProgressMonitor.bootstrapState = BootstrapProgressMonitor.BOOTSTRAP_COMPLETE;
                        BootstrapProgressMonitor.class.notifyAll();
                    } else if (platformEvent.getEventStatus() != null && platformEvent.getEventStatus()
                            .equalsIgnoreCase(RuntimeConstants.BOOTSTRAP_STOP_STATE)) {
                        BootstrapProgressMonitor.bootstrapState = BootstrapProgressMonitor.BOOTSTRAP_IN_PROGRESS;
                    }
                }

            }
        }
    }

}