8046902: Remove sun.misc.Timer
authorchegar
Tue, 17 Jun 2014 10:47:07 +0100
changeset 24979 b7bbc918ad4b
parent 24978 fd94ec11f272
child 24980 dbf4ae2cafa4
8046902: Remove sun.misc.Timer Reviewed-by: rriggs, mduigou, iris
jdk/src/share/classes/sun/misc/Timeable.java
jdk/src/share/classes/sun/misc/Timer.java
--- a/jdk/src/share/classes/sun/misc/Timeable.java	Mon Jun 09 17:18:14 2014 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,45 +0,0 @@
-/*
- * Copyright (c) 1995, Oracle and/or its affiliates. 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.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package sun.misc;
-
-/**
- * This interface is used by the Timer class.  A class that uses
- * Timer objects must implement this interface.
- *
- * @see Timer
- * @author Patrick Chan
- */
-public interface Timeable {
-    /**
-     * This method is executed every time a timer owned by this
-     * object ticks.  An object can own more than one timer but
-     * all timers call this method when they tick;
-     * you can use the supplied timer parameter to determine
-     * which timer has ticked.
-     * @param timer a handle to the timer that has just ticked.
-     */
-    public void tick(Timer timer);
-}
--- a/jdk/src/share/classes/sun/misc/Timer.java	Mon Jun 09 17:18:14 2014 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,647 +0,0 @@
-/*
- * Copyright (c) 1995, Oracle and/or its affiliates. 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.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package sun.misc;
-
-/**
-    A Timer object is used by algorithms that require timed events.
-    For example, in an animation loop, a timer would help in
-    determining when to change frames.
-
-    A timer has an interval which determines when it "ticks";
-    that is, a timer delays for the specified interval and then
-    it calls the owner's tick() method.
-
-    Here's an example of creating a timer with a 5 sec interval:
-
-    <pre>
-    class Main implements Timeable {
-        public void tick(Timer timer) {
-            System.out.println("tick");
-        }
-        public static void main(String args[]) {
-            (new Timer(this, 5000)).cont();
-        }
-    }
-    </pre>
-
-    A timer can be stopped, continued, or reset at any time.
-    A timer's state is not stopped while it's calling the
-    owner's tick() method.
-
-    A timer can be regular or irregular.  If in regular mode,
-    a timer ticks at the specified interval, regardless of
-    how long the owner's tick() method takes.  While the timer
-    is running, no ticks are ever discarded.  That means that if
-    the owner's tick() method takes longer than the interval,
-    the ticks that would have occurred are delivered immediately.
-
-    In irregular mode, a timer starts delaying for exactly
-    the specified interval only after the tick() method returns.
-
-    Synchronization issues: do not hold the timer's monitor
-    while calling any of the Timer operations below otherwise
-    the Timer class will deadlock.
-
-    @author     Patrick Chan
-*/
-
-/*
-    Synchronization issues:  there are two data structures that
-    require locking.  A Timer object and the Timer queue
-    (described in the TimerThread class).  To avoid deadlock,
-    the timer queue monitor is always acquired before the timer
-    object's monitor.  However, the timer queue monitor is acquired
-    only if the timer operation will make use of the timer
-    queue, e.g. stop().
-
-    The class monitor on the class TimerThread severs as the monitor
-    to the timer queue.
-
-    Possible feature: perhaps a timer should have an associated
-    thread priority.  The thread that makes the callback temporarily
-    takes on that priority before calling the owner's tick() method.
-*/
-
-public class Timer {
-    /**
-     * This is the owner of the timer.  Its tick method is
-     * called when the timer ticks.
-     */
-    public Timeable owner;
-
-    /*
-     * This is the interval of time in ms.
-     */
-    long interval;
-
-    /*
-     * This variable is used for two different purposes.
-     * This is done in order to save space.
-     * If 'stopped' is true, this variable holds the time
-     * that the timer was stopped; otherwise, this variable
-     * is used by the TimerThread to determine when the timer
-     * should tick.
-     */
-    long sleepUntil;
-
-    /*
-     * This is the time remaining before the timer ticks.  It
-     * is only valid if 'stopped' is true.  If the timer is
-     * continued, the next tick will happen remaingTime
-     * milliseconds later.
-     */
-    long remainingTime;
-
-    /*
-     * True iff the timer is in regular mode.
-     */
-    boolean regular;
-
-    /*
-     * True iff the timer has been stopped.
-     */
-    boolean stopped;
-
-    /* **************************************************************
-     * Timer queue-related variables
-     * ************************************************************** */
-
-    /*
-     * A link to another timer object.  This is used while the
-     * timer object is enqueued in the timer queue.
-     */
-    Timer next;
-
-    /* **************************************************************
-     * Timer methods
-     * ************************************************************** */
-
-    /*
-     * This variable holds a handle to the TimerThread class for
-     * the purpose of getting at the class monitor.  The reason
-     * why Class.forName("TimerThread") is not used is because it
-     * doesn't appear to work when loaded via a net class loader.
-     */
-    static TimerThread timerThread = null;
-
-    /**
-     * Creates a timer object that is owned by 'owner' and
-     * with the interval 'interval' milliseconds.  The new timer
-     * object is stopped and is regular.  getRemainingTime()
-     * return 'interval' at this point.  getStopTime() returns
-     * the time this object was created.
-     * @param owner    owner of the timer object
-     * @param interval interval of the timer in milliseconds
-     */
-    public Timer(Timeable owner, long interval) {
-        this.owner = owner;
-        this.interval = interval;
-        remainingTime = interval;
-        regular = true;
-        sleepUntil = System.currentTimeMillis();
-        stopped = true;
-        synchronized (getClass()) {
-            if (timerThread == null) {
-                timerThread = new TimerThread();
-            }
-        }
-    }
-
-    /**
-     * Returns true if this timer is stopped.
-     */
-    public synchronized boolean isStopped() {
-        return stopped;
-    }
-
-    /**
-     * Stops the timer.  The amount of time the timer has already
-     * delayed is saved so if the timer is continued, it will only
-     * delay for the amount of time remaining.
-     * Note that even after stopping a timer, one more tick may
-     * still occur.
-     * This method is MT-safe; i.e. it is synchronized but for
-     * implementation reasons, the synchronized modifier cannot
-     * be included in the method declaration.
-     */
-    public void stop() {
-        long now = System.currentTimeMillis();
-
-        synchronized (timerThread) {
-            synchronized (this) {
-                if (!stopped) {
-                    TimerThread.dequeue(this);
-                    remainingTime = Math.max(0, sleepUntil - now);
-                    sleepUntil = now;        // stop time
-                    stopped = true;
-                }
-            }
-        }
-    }
-
-    /**
-     * Continue the timer.  The next tick will come at getRemainingTime()
-     * milliseconds later.  If the timer is not stopped, this
-     * call will be a no-op.
-     * This method is MT-safe; i.e. it is synchronized but for
-     * implementation reasons, the synchronized modifier cannot
-     * be included in the method declaration.
-     */
-    public void cont() {
-        synchronized (timerThread) {
-            synchronized (this) {
-                if (stopped) {
-                    // The TimerTickThread avoids requeuing the
-                    // timer only if the sleepUntil value has changed.
-                    // The following guarantees that the sleepUntil
-                    // value will be different; without this guarantee,
-                    // it's theoretically possible for the timer to be
-                    // inserted twice.
-                    sleepUntil = Math.max(sleepUntil + 1,
-                        System.currentTimeMillis() + remainingTime);
-                    TimerThread.enqueue(this);
-                    stopped = false;
-                }
-            }
-        }
-    }
-
-    /**
-     * Resets the timer's remaining time to the timer's interval.
-     * If the timer's running state is not altered.
-     */
-    public void reset() {
-        synchronized (timerThread) {
-            synchronized (this) {
-                setRemainingTime(interval);
-            }
-        }
-    }
-
-    /**
-     * Returns the time at which the timer was last stopped.  The
-     * return value is valid only if the timer is stopped.
-     */
-    public synchronized long getStopTime() {
-        return sleepUntil;
-    }
-
-    /**
-     * Returns the timer's interval.
-     */
-    public synchronized long getInterval() {
-        return interval;
-    }
-
-    /**
-     * Changes the timer's interval.  The new interval setting
-     * does not take effect until after the next tick.
-     * This method does not alter the remaining time or the
-     * running state of the timer.
-     * @param interval new interval of the timer in milliseconds
-     */
-    public synchronized void setInterval(long interval) {
-        this.interval = interval;
-    }
-
-    /**
-     * Returns the remaining time before the timer's next tick.
-     * The return value is valid only if timer is stopped.
-     */
-    public synchronized long getRemainingTime() {
-        return remainingTime;
-    }
-
-    /**
-     * Sets the remaining time before the timer's next tick.
-     * This method does not alter the timer's running state.
-     * This method is MT-safe; i.e. it is synchronized but for
-     * implementation reasons, the synchronized modifier cannot
-     * be included in the method declaration.
-     * @param time new remaining time in milliseconds.
-     */
-    public void setRemainingTime(long time) {
-        synchronized (timerThread) {
-            synchronized (this) {
-                if (stopped) {
-                    remainingTime = time;
-                } else {
-                    stop();
-                    remainingTime = time;
-                    cont();
-                }
-            }
-        }
-    }
-
-    /**
-     * In regular mode, a timer ticks at the specified interval,
-     * regardless of how long the owner's tick() method takes.
-     * While the timer is running, no ticks are ever discarded.
-     * That means that if the owner's tick() method takes longer
-     * than the interval, the ticks that would have occurred are
-     * delivered immediately.
-     *
-     * In irregular mode, a timer starts delaying for exactly
-     * the specified interval only after the tick() method returns.
-     */
-    public synchronized void setRegular(boolean regular) {
-        this.regular = regular;
-    }
-
-    /*
-     * This method is used only for testing purposes.
-     */
-    protected Thread getTimerThread() {
-        return TimerThread.timerThread;
-    }
-}
-
-
-/*
-
-This class implements the timer queue and is exclusively used by the
-Timer class.  There are only two methods exported to the Timer class -
-enqueue, for inserting a timer into queue and dequeue, for removing
-a timer from the queue.
-
-A timer in the timer queue is awaiting a tick.  When a timer is to be
-ticked, it is removed from the timer queue before the owner's tick()
-method is called.
-
-A single timer thread manages the timer queue.  This timer thread
-looks at the head of the timer queue and delays until it's time for
-the timer to tick.  When the time comes, the timer thread creates a
-callback thread to call the timer owner's tick() method.  The timer
-thread then processes the next timer in the queue.
-
-When a timer is inserted at the head of the queue, the timer thread is
-notified.  This causes the timer thread to prematurely wake up and
-process the new head of the queue.
-
-*/
-
-class TimerThread extends Thread {
-    /*
-     * Set to true to get debugging output.
-     */
-    public static boolean debug = false;
-
-    /*
-     * This is a handle to the thread managing the thread queue.
-     */
-    static TimerThread timerThread;
-
-    /*
-     * This flag is set if the timer thread has been notified
-     * while it was in the timed wait.  This flag allows the
-     * timer thread to tell whether or not the wait completed.
-     */
-    static boolean notified = false;
-
-    protected TimerThread() {
-        super("TimerThread");
-        timerThread = this;
-        start();
-    }
-
-    public synchronized void run() {
-        while (true) {
-            long delay;
-
-            while (timerQueue == null) {
-                try {
-                    wait();
-                } catch (InterruptedException ex) {
-                   // Just drop through and check timerQueue.
-                }
-            }
-            notified = false;
-            delay = timerQueue.sleepUntil - System.currentTimeMillis();
-            if (delay > 0) {
-                try {
-                    wait(delay);
-                } catch (InterruptedException ex) {
-                    // Just drop through.
-                }
-            }
-            // remove from timer queue.
-            if (!notified) {
-                Timer timer = timerQueue;
-                timerQueue = timerQueue.next;
-                TimerTickThread thr = TimerTickThread.call(
-                    timer, timer.sleepUntil);
-                if (debug) {
-                    long delta = (System.currentTimeMillis() - timer.sleepUntil);
-                    System.out.println("tick(" + thr.getName() + ","
-                        + timer.interval + ","+delta+ ")");
-                    if (delta > 250) {
-                        System.out.println("*** BIG DELAY ***");
-                    }
-                }
-            }
-        }
-    }
-
-    /* *******************************************************
-       Timer Queue
-       ******************************************************* */
-
-    /*
-     * The timer queue is a queue of timers waiting to tick.
-     */
-    static Timer timerQueue = null;
-
-    /*
-     * Uses timer.sleepUntil to determine where in the queue
-     * to insert the timer object.
-     * A new ticker thread is created only if the timer
-     * is inserted at the beginning of the queue.
-     * The timer must not already be in the queue.
-     * Assumes the caller has the TimerThread monitor.
-     */
-    static protected void enqueue(Timer timer) {
-        Timer prev = null;
-        Timer cur = timerQueue;
-
-        if (cur == null || timer.sleepUntil <= cur.sleepUntil) {
-            // insert at front of queue
-            timer.next = timerQueue;
-            timerQueue = timer;
-            notified = true;
-            timerThread.notify();
-        } else {
-            do {
-                prev = cur;
-                cur = cur.next;
-            } while (cur != null && timer.sleepUntil > cur.sleepUntil);
-            // insert or append to the timer queue
-            timer.next = cur;
-            prev.next = timer;
-        }
-        if (debug) {
-            long now = System.currentTimeMillis();
-
-            System.out.print(Thread.currentThread().getName()
-                + ": enqueue " + timer.interval + ": ");
-            cur = timerQueue;
-            while(cur != null) {
-                long delta = cur.sleepUntil - now;
-                System.out.print(cur.interval + "(" + delta + ") ");
-                cur = cur.next;
-            }
-            System.out.println();
-        }
-    }
-
-    /*
-     * If the timer is not in the queue, returns false;
-     * otherwise removes the timer from the timer queue and returns true.
-     * Assumes the caller has the TimerThread monitor.
-     */
-    static protected boolean dequeue(Timer timer) {
-        Timer prev = null;
-        Timer cur = timerQueue;
-
-        while (cur != null && cur != timer) {
-            prev = cur;
-            cur = cur.next;
-        }
-        if (cur == null) {
-            if (debug) {
-                System.out.println(Thread.currentThread().getName()
-                    + ": dequeue " + timer.interval + ": no-op");
-            }
-            return false;
-        }       if (prev == null) {
-            timerQueue = timer.next;
-            notified = true;
-            timerThread.notify();
-        } else {
-            prev.next = timer.next;
-        }
-        timer.next = null;
-        if (debug) {
-            long now = System.currentTimeMillis();
-
-            System.out.print(Thread.currentThread().getName()
-                + ": dequeue " + timer.interval + ": ");
-            cur = timerQueue;
-            while(cur != null) {
-                long delta = cur.sleepUntil - now;
-                System.out.print(cur.interval + "(" + delta + ") ");
-                cur = cur.next;
-            }
-            System.out.println();
-        }
-        return true;
-    }
-
-    /*
-     * Inserts the timer back into the queue.  This method
-     * is used by a callback thread after it has called the
-     * timer owner's tick() method.  This method recomputes
-     * the sleepUntil field.
-     * Assumes the caller has the TimerThread and Timer monitor.
-     */
-    protected static void requeue(Timer timer) {
-        if (!timer.stopped) {
-            long now = System.currentTimeMillis();
-            if (timer.regular) {
-                timer.sleepUntil += timer.interval;
-            } else {
-                timer.sleepUntil = now + timer.interval;
-            }
-            enqueue(timer);
-        } else if (debug) {
-            System.out.println(Thread.currentThread().getName()
-                + ": requeue " + timer.interval + ": no-op");
-        }
-    }
-}
-
-/*
-
-This class implements a simple thread whose only purpose is to call a
-timer owner's tick() method.  A small fixed-sized pool of threads is
-maintained and is protected by the class monitor.  If the pool is
-exhausted, a new thread is temporarily created and destroyed when
-done.
-
-A thread that's in the pool waits on it's own monitor.  When the
-thread is retrieved from the pool, the retriever notifies the thread's
-monitor.
-
-*/
-
-class TimerTickThread extends Thread {
-    /*
-     * Maximum size of the thread pool.
-     */
-    static final int MAX_POOL_SIZE = 3;
-
-    /*
-     * Number of threads in the pool.
-     */
-    static int curPoolSize = 0;
-
-    /*
-     * The pool of timer threads.
-     */
-    static TimerTickThread pool = null;
-
-    /*
-     * Is used when linked into the thread pool.
-     */
-    TimerTickThread next = null;
-
-    /*
-     * This is the handle to the timer whose owner's
-     * tick() method will be called.
-     */
-    Timer timer;
-
-    /*
-     * The value of a timer's sleepUntil value is captured here.
-     * This is used to determine whether or not the timer should
-     * be reinserted into the queue.  If the timer's sleepUntil
-     * value has changed, the timer is not reinserted.
-     */
-    long lastSleepUntil;
-
-    /*
-     * Creates a new callback thread to call the timer owner's
-     * tick() method.  A thread is taken from the pool if one
-     * is available, otherwise, a new thread is created.
-     * The thread handle is returned.
-     */
-    protected static synchronized TimerTickThread call(
-            Timer timer, long sleepUntil) {
-        TimerTickThread thread = pool;
-
-        if (thread == null) {
-            // create one.
-            thread = new TimerTickThread();
-            thread.timer = timer;
-            thread.lastSleepUntil = sleepUntil;
-            thread.start();
-        } else {
-            pool = pool.next;
-            thread.timer = timer;
-            thread.lastSleepUntil = sleepUntil;
-            synchronized (thread) {
-                thread.notify();
-            }
-        }
-        return thread;
-    }
-
-    /*
-     * Returns false if the thread should simply exit;
-     * otherwise the thread is returned the pool, where
-     * it waits to be notified.  (I did try to use the
-     * class monitor but the time between the notify
-     * and breaking out of the wait seemed to take
-     * significantly longer; need to look into this later.)
-     */
-    private boolean returnToPool() {
-        synchronized (getClass()) {
-            if (curPoolSize >= MAX_POOL_SIZE) {
-                return false;
-            }
-            next = pool;
-            pool = this;
-            curPoolSize++;
-            timer = null;
-        }
-        while (timer == null) {
-            synchronized (this) {
-                try {
-                    wait();
-                } catch (InterruptedException ex) {
-                   // Just drop through and retest timer.
-                }
-            }
-        }
-        synchronized (getClass()) {
-            curPoolSize--;
-        }
-        return true;
-    }
-
-    public void run() {
-        do {
-            timer.owner.tick(timer);
-            synchronized (TimerThread.timerThread) {
-                synchronized (timer) {
-                    if (lastSleepUntil == timer.sleepUntil) {
-                        TimerThread.requeue(timer);
-                    }
-                }
-            }
-        } while (returnToPool());
-    }
-}