/*

 * Copyright 2002-2008 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.misc;

import java.util.Vector;

import java.io.FileWriter;

import java.io.File;

import java.io.OutputStreamWriter;

import java.io.Writer;

/**

 * This class is intended to be a central place for the jdk to

 * log timing events of interest.  There is pre-defined event

 * of startTime, as well as a general

 * mechanism of setting aribtrary times in an array.

 * All unreserved times in the array can be used by callers

 * in application-defined situations.  The caller is responsible

 * for setting and getting all times and for doing whatever

 * analysis is interesting; this class is merely a central container

 * for those timing values.

 * Note that, due to the variables in this class being static,

 * use of particular time values by multiple applets will cause

 * confusing results.  For example, if plugin runs two applets

 * simultaneously, the initTime for those applets will collide

 * and the results may be undefined.

 * <P>

 * To automatically track startup performance in an app or applet,

 * use the command-line parameter sun.perflog as follows:<BR>

 *     -Dsun.perflog[=file:<filename>]

 * <BR>

 * where simply using the parameter with no value will enable output

 * to the console and a value of "file:<filename>" will cause

 * that given filename to be created and used for all output.

 * <P>

 * By default, times are measured using System.currentTimeMillis().  To use

 * System.nanoTime() instead, add the command-line parameter:<BR>

       -Dsun.perflog.nano=true

 * <BR>

 * <P>

 * <B>Warning: Use at your own risk!</B>

 * This class is intended for internal testing

 * purposes only and may be removed at any time.  More

 * permanent monitoring and profiling APIs are expected to be

 * developed for future releases and this class will cease to

 * exist once those APIs are in place.

 * @author Chet Haase

 */

public class PerformanceLogger {

    // Timing values of global interest

    private static final int START_INDEX    = 0;    // VM start

    private static final int LAST_RESERVED  = START_INDEX;

    private static boolean perfLoggingOn = false;

    private static boolean useNanoTime = false;

    private static Vector<TimeData> times;

    private static String logFileName = null;

    private static Writer logWriter = null;

    static {

        String perfLoggingProp =

            java.security.AccessController.doPrivileged(

            new sun.security.action.GetPropertyAction("sun.perflog"));

        if (perfLoggingProp != null) {

            perfLoggingOn = true;

            // Check if we should use nanoTime

            String perfNanoProp =

                java.security.AccessController.doPrivileged(

                new sun.security.action.GetPropertyAction("sun.perflog.nano"));

            if (perfNanoProp != null) {

                useNanoTime = true;

            }

            // Now, figure out what the user wants to do with the data

            if (perfLoggingProp.regionMatches(true, 0, "file:", 0, 5)) {

                logFileName = perfLoggingProp.substring(5);

            }

            if (logFileName != null) {

                if (logWriter == null) {

                    java.security.AccessController.doPrivileged(

                    new java.security.PrivilegedAction<Void>() {

                        public Void run() {

                            try {

                                File logFile = new File(logFileName);

                                logFile.createNewFile();

                                logWriter = new FileWriter(logFile);

                            } catch (Exception e) {

                                System.out.println(e + ": Creating logfile " +

                                                   logFileName +

                                                   ".  Log to console");

                            }

                            return null;

                        }

                    });

                }

            }

            if (logWriter == null) {

                logWriter = new OutputStreamWriter(System.out);

            }

        }

        times = new Vector<TimeData>(10);

        // Reserve predefined slots

        for (int i = 0; i <= LAST_RESERVED; ++i) {

            times.add(new TimeData("Time " + i + " not set", 0));

        }

    }

    /**

     * Returns status of whether logging is enabled or not.  This is

     * provided as a convenience method so that users do not have to

     * perform the same GetPropertyAction check as above to determine whether

     * to enable performance logging.

     */

    public static boolean loggingEnabled() {

        return perfLoggingOn;

    }

    /**

     * Internal class used to store time/message data together.

     */

    static class TimeData {

        String message;

        long time;

        TimeData(String message, long time) {

            this.message = message;

            this.time = time;

        }

        String getMessage() {

            return message;

        }

        long getTime() {

            return time;

        }

    }

    /**

     * Return the current time, in millis or nanos as appropriate

     */

    private static long getCurrentTime() {

        if (useNanoTime) {

            return System.nanoTime();

        } else {

            return System.currentTimeMillis();

        }

    }

    /**

     * Sets the start time.  Ideally, this is the earliest time available

     * during the startup of a Java applet or application.  This time is

     * later used to analyze the difference between the initial startup

     * time and other events in the system (such as an applet's init time).

     */

    public static void setStartTime(String message) {

        if (loggingEnabled()) {

            long nowTime = getCurrentTime();

            setStartTime(message, nowTime);

        }

    }

    /**

     * Sets the start time.

     * This version of the method is

     * given the time to log, instead of expecting this method to

     * get the time itself.  This is done in case the time was

     * recorded much earlier than this method was called.

     */

    public static void setStartTime(String message, long time) {

        if (loggingEnabled()) {

            times.set(START_INDEX, new TimeData(message, time));

        }

    }

    /**

     * Gets the start time, which should be the time when

     * the java process started, prior to the VM actually being

     * loaded.

     */

    public static long getStartTime() {

        if (loggingEnabled()) {

            return times.get(START_INDEX).getTime();

        } else {

            return 0;

        }

    }

    /**

     * Sets the value of a given time and returns the index of the

     * slot that that time was stored in.

     */

    public static int setTime(String message) {

        if (loggingEnabled()) {

            long nowTime = getCurrentTime();

            return setTime(message, nowTime);

        } else {

            return 0;

        }

    }

    /**

     * Sets the value of a given time and returns the index of the

     * slot that that time was stored in.

     * This version of the method is

     * given the time to log, instead of expecting this method to

     * get the time itself.  This is done in case the time was

     * recorded much earlier than this method was called.

     */

    public static int setTime(String message, long time) {

        if (loggingEnabled()) {

            // times is already synchronized, but we need to ensure that

            // the size used in times.set() is the same used when returning

            // the index of that operation.

            synchronized (times) {

                times.add(new TimeData(message, time));

                return (times.size() - 1);

            }

        } else {

            return 0;

        }

    }

    /**

     * Returns time at given index.

     */

    public static long getTimeAtIndex(int index) {

        if (loggingEnabled()) {

            return times.get(index).getTime();

        } else {

            return 0;

        }

    }

    /**

     * Returns message at given index.

     */

    public static String getMessageAtIndex(int index) {

        if (loggingEnabled()) {

            return times.get(index).getMessage();

        } else {

            return null;

        }

    }

    /**

     * Outputs all data to parameter-specified Writer object

     */

    public static void outputLog(Writer writer) {

        if (loggingEnabled()) {

            try {

                synchronized(times) {

                    for (int i = 0; i < times.size(); ++i) {

                        TimeData td = times.get(i);

                        if (td != null) {

                            writer.write(i + " " + td.getMessage() + ": " +

                        }

                    }

                }

                writer.flush();

            } catch (Exception e) {

                System.out.println(e + ": Writing performance log to " +

                                   writer);

            }

        }

    }

    /**

     * Outputs all data to whatever location the user specified

     * via sun.perflog command-line parameter.

     */

    public static void outputLog() {

        outputLog(logWriter);

    }

}