com.almende.eve.instantiation.HibernationHandler.java Source code

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Here is the source code for com.almende.eve.instantiation.HibernationHandler.java

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/*
 * Copyright: Almende B.V. (2014), Rotterdam, The Netherlands
 * License: The Apache Software License, Version 2.0
 */
package com.almende.eve.instantiation;

import java.lang.ref.WeakReference;

import com.almende.eve.capabilities.handler.Handler;
import com.fasterxml.jackson.annotation.JsonIgnore;

/**
 * The Class WakeHandler.
 * 
 * @param <T>
 *            the generic type
 */
public class HibernationHandler<T> implements Handler<T> {
    private WeakReference<T> referent = null;
    private final Object wakeLock = new Object();
    private String wakeKey = null;
    private InstantiationService service = null;

    /**
     * Instantiates a new wake handler.
     */
    public HibernationHandler() {
    }

    /**
     * Instantiates a new wake handler.
     * 
     * @param referent
     *            the referent
     * @param wakeKey
     *            the wake key
     * @param service
     *            the wake service where this referent is registered.
     */
    public HibernationHandler(final T referent, final String wakeKey, final InstantiationService service) {
        this.referent = new WeakReference<T>(referent);
        this.setWakeKey(wakeKey);
        this.service = service;
    }

    /*
     * (non-Javadoc)
     * @see com.almende.eve.capabilities.handler.Handler#get()
     */
    @Override
    @JsonIgnore
    public T get() {
        if (referent.get() == null) {
            service.init(getWakeKey());
        }
        while (referent.get() == null) {
            synchronized (wakeLock) {
                try {
                    wakeLock.wait();
                } catch (final InterruptedException e) {
                }
            }
        }
        return referent.get();
    }

    /**
     * Gets the no wait.
     *
     * @return the no wait
     */
    @JsonIgnore
    public T getNoWait() {
        return this.referent.get();
    }

    /*
     * (non-Javadoc)
     * @see com.almende.eve.capabilities.handler.Handler#update(com.almende.eve.
     * capabilities.handler.Handler)
     */
    @Override
    public void update(final Handler<T> newHandler) {
        this.referent = new WeakReference<T>(newHandler.get());

        // Can this be done in a cleaner way?
        if (newHandler instanceof HibernationHandler) {
            final HibernationHandler<T> other = (HibernationHandler<T>) newHandler;
            this.wakeKey = other.getWakeKey();
            synchronized (wakeLock) {
                wakeLock.notifyAll();
            }
        }
    }

    /**
     * Gets the wake key.
     * 
     * @return the wake key
     */
    public String getWakeKey() {
        return wakeKey;
    }

    /**
     * Sets the wake key.
     * 
     * @param wakeKey
     *            the new wake key
     */
    public void setWakeKey(final String wakeKey) {
        this.wakeKey = wakeKey;
    }

    /*
     * (non-Javadoc)
     * @see com.almende.eve.capabilities.handler.Handler#getKey()
     */
    @Override
    public String getKey() {
        return wakeKey;
    }

}