os/dtrace/ProcessEvent.java

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * ident    "%Z%%M% %I% %E% SMI"
 */
package org.opensolaris.os.dtrace;

import java.io.*;
import java.util.EventObject;

/**
 * Notification that the state of a target process designated by {@link
 * Consumer#createProcess(String command)} or {@link
 * Consumer#grabProcess(int pid)} has changed.
 *
 * @see ConsumerListener#processStateChanged(ProcessEvent e)
 *
 * @author Tom Erickson
 */
public class ProcessEvent extends EventObject {
    static final long serialVersionUID = -3779443761929558702L;

    /** @serial */
    private ProcessState processState;

    /**
     * Creates a {@link ConsumerListener#processStateChanged(ProcessEvent e)
     * processStateChanged()} event to notify listeners of a process
     * state change.
     *
     * @param source the {@link Consumer} that is the source of this event
     * @throws NullPointerException if the given process state is {@code
     * null}
     */
    public
    ProcessEvent(Object source, ProcessState p)
    {
    super(source);
    processState = p;
    validate();
    }

    private final void
    validate()
    {
    if (processState == null) {
        throw new NullPointerException("process state is null");
    }
    }

    /**
     * Gets the process state.
     *
     * @return non-null process state
     */
    public ProcessState
    getProcessState()
    {
    return processState;
    }

    private void
    readObject(ObjectInputStream s)
            throws IOException, ClassNotFoundException
    {
    s.defaultReadObject();
    // check invariants
    try {
        validate();
    } catch (Exception e) {
        InvalidObjectException x = new InvalidObjectException(
            e.getMessage());
        x.initCause(e);
        throw x;
    }
    }

    /**
     * Gets a string representation of this event useful for logging and
     * not intended for display.  The exact details of the
     * representation are unspecified and subject to change, but the
     * following format may be regarded as typical:
     * <pre><code>
     * class-name[property1 = value1, property2 = value2]
     * </code></pre>
     */
    public String
    toString()
    {
    StringBuilder buf = new StringBuilder();
    buf.append(ProcessEvent.class.getName());
    buf.append("[source = ");
    buf.append(getSource());
    buf.append(", processState = ");
    buf.append(processState);
    buf.append(']');
    return buf.toString();
    }
}