/*

  * 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

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 /*

  * This file is available under and governed by the GNU General Public

  * License version 2 only, as published by the Free Software Foundation.

  * However, the following notice accompanied the original version of this

  * file:

  *

  * Written by Doug Lea with assistance from members of JCP JSR-166

  * Expert Group and released to the public domain, as explained at

  * http://creativecommons.org/publicdomain/zero/1.0/

  */

 package java.util.concurrent;

 /**

  * A <tt>TimeUnit</tt> represents time durations at a given unit of

  * granularity and provides utility methods to convert across units,

  * and to perform timing and delay operations in these units.  A

  * <tt>TimeUnit</tt> does not maintain time information, but only

  * helps organize and use time representations that may be maintained

  * separately across various contexts.  A nanosecond is defined as one

  * thousandth of a microsecond, a microsecond as one thousandth of a

  * millisecond, a millisecond as one thousandth of a second, a minute

  * as sixty seconds, an hour as sixty minutes, and a day as twenty four

  * hours.

  *

  * <p>A <tt>TimeUnit</tt> is mainly used to inform time-based methods

  * how a given timing parameter should be interpreted. For example,

  * the following code will timeout in 50 milliseconds if the {@link

  * java.util.concurrent.locks.Lock lock} is not available:

  *

  * <pre>  Lock lock = ...;

  *  if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...

  * </pre>

  * while this code will timeout in 50 seconds:

  * <pre>

  *  Lock lock = ...;

  *  if (lock.tryLock(50L, TimeUnit.SECONDS)) ...

  * </pre>

  *

  * Note however, that there is no guarantee that a particular timeout

  * implementation will be able to notice the passage of time at the

  * same granularity as the given <tt>TimeUnit</tt>.

  *

  * @since 1.5

  * @author Doug Lea

  */

 public enum TimeUnit {

     NANOSECONDS {

         public long toNanos(long d)   { return d; }

         public long toMicros(long d)  { return d/(C1/C0); }

         public long toMillis(long d)  { return d/(C2/C0); }

         public long toSeconds(long d) { return d/(C3/C0); }

         public long toMinutes(long d) { return d/(C4/C0); }

         public long toHours(long d)   { return d/(C5/C0); }

         public long toDays(long d)    { return d/(C6/C0); }

         public long convert(long d, TimeUnit u) { return u.toNanos(d); }

         int excessNanos(long d, long m) { return (int)(d - (m*C2)); }

     },

     MICROSECONDS {

         public long toNanos(long d)   { return x(d, C1/C0, MAX/(C1/C0)); }

         public long toMicros(long d)  { return d; }

         public long toMillis(long d)  { return d/(C2/C1); }

         public long toSeconds(long d) { return d/(C3/C1); }

         public long toMinutes(long d) { return d/(C4/C1); }

         public long toHours(long d)   { return d/(C5/C1); }

         public long toDays(long d)    { return d/(C6/C1); }

         public long convert(long d, TimeUnit u) { return u.toMicros(d); }

         int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }

     },

     MILLISECONDS {

         public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }

         public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }

         public long toMillis(long d)  { return d; }

         public long toSeconds(long d) { return d/(C3/C2); }

         public long toMinutes(long d) { return d/(C4/C2); }

         public long toHours(long d)   { return d/(C5/C2); }

         public long toDays(long d)    { return d/(C6/C2); }

         public long convert(long d, TimeUnit u) { return u.toMillis(d); }

         int excessNanos(long d, long m) { return 0; }

     },

     SECONDS {

         public long toNanos(long d)   { return x(d, C3/C0, MAX/(C3/C0)); }

         public long toMicros(long d)  { return x(d, C3/C1, MAX/(C3/C1)); }

         public long toMillis(long d)  { return x(d, C3/C2, MAX/(C3/C2)); }

         public long toSeconds(long d) { return d; }

         public long toMinutes(long d) { return d/(C4/C3); }

         public long toHours(long d)   { return d/(C5/C3); }

         public long toDays(long d)    { return d/(C6/C3); }

         public long convert(long d, TimeUnit u) { return u.toSeconds(d); }

         int excessNanos(long d, long m) { return 0; }

     },

     MINUTES {

         public long toNanos(long d)   { return x(d, C4/C0, MAX/(C4/C0)); }

         public long toMicros(long d)  { return x(d, C4/C1, MAX/(C4/C1)); }

         public long toMillis(long d)  { return x(d, C4/C2, MAX/(C4/C2)); }

         public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }

         public long toMinutes(long d) { return d; }

         public long toHours(long d)   { return d/(C5/C4); }

         public long toDays(long d)    { return d/(C6/C4); }

         public long convert(long d, TimeUnit u) { return u.toMinutes(d); }

         int excessNanos(long d, long m) { return 0; }

     },

     HOURS {

         public long toNanos(long d)   { return x(d, C5/C0, MAX/(C5/C0)); }

         public long toMicros(long d)  { return x(d, C5/C1, MAX/(C5/C1)); }

         public long toMillis(long d)  { return x(d, C5/C2, MAX/(C5/C2)); }

         public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }

         public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }

         public long toHours(long d)   { return d; }

         public long toDays(long d)    { return d/(C6/C5); }

         public long convert(long d, TimeUnit u) { return u.toHours(d); }

         int excessNanos(long d, long m) { return 0; }

     },

     DAYS {

         public long toNanos(long d)   { return x(d, C6/C0, MAX/(C6/C0)); }

         public long toMicros(long d)  { return x(d, C6/C1, MAX/(C6/C1)); }

         public long toMillis(long d)  { return x(d, C6/C2, MAX/(C6/C2)); }

         public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }

         public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }

         public long toHours(long d)   { return x(d, C6/C5, MAX/(C6/C5)); }

         public long toDays(long d)    { return d; }

         public long convert(long d, TimeUnit u) { return u.toDays(d); }

         int excessNanos(long d, long m) { return 0; }

     };

     // Handy constants for conversion methods

     static final long C0 = 1L;

     static final long C1 = C0 * 1000L;

     static final long C2 = C1 * 1000L;

     static final long C3 = C2 * 1000L;

     static final long C4 = C3 * 60L;

     static final long C5 = C4 * 60L;

     static final long C6 = C5 * 24L;

     static final long MAX = Long.MAX_VALUE;

     /**

      * Scale d by m, checking for overflow.

      * This has a short name to make above code more readable.

      */

     static long x(long d, long m, long over) {

         if (d >  over) return Long.MAX_VALUE;

         if (d < -over) return Long.MIN_VALUE;

         return d * m;

     }

     // To maintain full signature compatibility with 1.5, and to improve the

     // clarity of the generated javadoc (see 6287639: Abstract methods in

     // enum classes should not be listed as abstract), method convert

     // etc. are not declared abstract but otherwise act as abstract methods.

     /**

      * Convert the given time duration in the given unit to this

      * unit.  Conversions from finer to coarser granularities

      * truncate, so lose precision. For example converting

      * <tt>999</tt> milliseconds to seconds results in

      * <tt>0</tt>. Conversions from coarser to finer granularities

      * with arguments that would numerically overflow saturate to

      * <tt>Long.MIN_VALUE</tt> if negative or <tt>Long.MAX_VALUE</tt>

      * if positive.

      *

      * <p>For example, to convert 10 minutes to milliseconds, use:

      * <tt>TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)</tt>

      *

      * @param sourceDuration the time duration in the given <tt>sourceUnit</tt>

      * @param sourceUnit the unit of the <tt>sourceDuration</tt> argument

      * @return the converted duration in this unit,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      */

     public long convert(long sourceDuration, TimeUnit sourceUnit) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>NANOSECONDS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      */

     public long toNanos(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>MICROSECONDS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      */

     public long toMicros(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>MILLISECONDS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      */

     public long toMillis(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>SECONDS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      */

     public long toSeconds(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>MINUTES.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      * @since 1.6

      */

     public long toMinutes(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>HOURS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration,

      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively

      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.

      * @see #convert

      * @since 1.6

      */

     public long toHours(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Equivalent to <tt>DAYS.convert(duration, this)</tt>.

      * @param duration the duration

      * @return the converted duration

      * @see #convert

      * @since 1.6

      */

     public long toDays(long duration) {

         throw new AbstractMethodError();

     }

     /**

      * Utility to compute the excess-nanosecond argument to wait,

      * sleep, join.

      * @param d the duration

      * @param m the number of milliseconds

      * @return the number of nanoseconds

      */

     abstract int excessNanos(long d, long m);

     /**

      * Performs a timed {@link Object#wait(long, int) Object.wait}

      * using this time unit.

      * This is a convenience method that converts timeout arguments

      * into the form required by the <tt>Object.wait</tt> method.

      *

      * <p>For example, you could implement a blocking <tt>poll</tt>

      * method (see {@link BlockingQueue#poll BlockingQueue.poll})

      * using:

      *

      *  <pre> {@code

      * public synchronized Object poll(long timeout, TimeUnit unit)

      *     throws InterruptedException {

      *   while (empty) {

      *     unit.timedWait(this, timeout);

      *     ...

      *   }

      * }}</pre>

      *

      * @param obj the object to wait on

      * @param timeout the maximum time to wait. If less than

      * or equal to zero, do not wait at all.

      * @throws InterruptedException if interrupted while waiting

      */

     public void timedWait(Object obj, long timeout)

             throws InterruptedException {

         if (timeout > 0) {

             long ms = toMillis(timeout);

             int ns = excessNanos(timeout, ms);

             obj.wait(ms, ns);

         }

     }

     /**

      * Performs a timed {@link Thread#join(long, int) Thread.join}

      * using this time unit.

      * This is a convenience method that converts time arguments into the

      * form required by the <tt>Thread.join</tt> method.

      *

      * @param thread the thread to wait for

      * @param timeout the maximum time to wait. If less than

      * or equal to zero, do not wait at all.

      * @throws InterruptedException if interrupted while waiting

      */

 //    public void timedJoin(Thread thread, long timeout)

 //            throws InterruptedException {

 //        if (timeout > 0) {

 //            long ms = toMillis(timeout);

 //            int ns = excessNanos(timeout, ms);

 //            thread.join(ms, ns);

 //        }

 //    }

     /**

      * Performs a {@link Thread#sleep(long, int) Thread.sleep} using

      * this time unit.

      * This is a convenience method that converts time arguments into the

      * form required by the <tt>Thread.sleep</tt> method.

      *

      * @param timeout the minimum time to sleep. If less than

      * or equal to zero, do not sleep at all.

      * @throws InterruptedException if interrupted while sleeping

      */

     public void sleep(long timeout) throws InterruptedException {

         if (timeout > 0) {

             long ms = toMillis(timeout);

             int ns = excessNanos(timeout, ms);

             Thread.sleep(ms, ns);

         }

     }

 }