org.pascani.dsl.lib.Event.java Source code

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Here is the source code for org.pascani.dsl.lib.Event.java

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/*
 * Copyright  2015 Universidad Icesi
 * 
 * This file is part of the Pascani project.
 * 
 * The Pascani project is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * The Pascani project is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with The Pascani project. If not, see <http://www.gnu.org/licenses/>.
 */
package org.pascani.dsl.lib;

import java.io.Serializable;
import java.util.UUID;

import com.google.common.collect.Range;

/**
 * Standard abstract implementation for simple events
 * 
 * @author Miguel Jimnez - Initial contribution and API
 */
public abstract class Event<T> implements Comparable<Event<T>>, Serializable {

    /**
     * Serial version UID
     */
    private static final long serialVersionUID = 4932084076805806298L;

    /**
     * The universally unique identifier of this event
     */
    protected final UUID identifier;

    /**
     * The universally unique identifier of the transaction of which this event
     * is part
     */
    protected final UUID transactionId;

    /**
     * The timestamp when this event is raised, in nanoseconds
     */
    protected final long timestamp;

    public Event(final UUID transactionId) {
        this.timestamp = System.currentTimeMillis();
        this.identifier = UUID.randomUUID();
        this.transactionId = transactionId;
    }

    /**
     * @return the universal unique identifier of this event
     */
    public UUID identifier() {
        return this.identifier;
    }

    /**
     * @return The universally unique identifier of the transaction of which
     *         this event is part
     */
    public UUID transactionId() {
        return this.transactionId;
    }

    /**
     * @return the timestamp when this event is raised, in nanoseconds
     */
    public long timestamp() {
        return this.timestamp;
    }

    /**
     * @return the value of this event
     */
    public abstract T value();

    /**
     * Checks whether this {@link Event} was raised within a given time window,
     * i.e., {@code this.timestamp} is contained in [ {@code start} ,
     * {@code end}].
     * 
     * @param start
     *            The initial timestamp of the time window
     * @param end
     *            The final timestamp of the time window
     * @return Whether the range [{@code start}, {@code end}] contains the final
     *         timestamp this object
     */
    public boolean isInTimeWindow(long start, long end) {
        return Range.closed(start, end).contains(this.timestamp);
    }

    /*
     * (non-Javadoc)
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((this.identifier == null) ? 0 : this.identifier.hashCode());
        return result;
    }

    /**
     * The result is {@code true} if and only if the argument is not
     * {@code null}, is an {@link Event} object with the same identifier
     * as {@code this} instance.
     */
    @Override
    public boolean equals(final Object obj) {
        if (this == obj)
            return true;
        else if ((null == obj) || (obj.getClass() != this.getClass()))
            return false;

        @SuppressWarnings("unchecked")
        Event<T> other = (Event<T>) obj;
        return this.compareTo(other) == 0;
    }

    protected int compareInt(long i1, long i2) {
        if (i1 < i2) {
            return -1;
        } else if (i1 > i2) {
            return +1;
        } else {
            return 0;
        }
    }

    /*
     * (non-Javadoc)
     * @see pascani.lang.Event#compareTo(pascani.lang.Event)
     */
    public int compareTo(final Event<T> o) {
        int v = 0;

        v = compareInt(this.timestamp, o.timestamp);
        if (v != 0)
            return v;

        v = this.identifier.compareTo(o.identifier);
        if (v != 0)
            return v;

        return v;
    }

}