mirror of git://gcc.gnu.org/git/gcc.git
332 lines
13 KiB
Java
332 lines
13 KiB
Java
/*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/licenses/publicdomain
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*/
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package java.util.concurrent;
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/**
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* A <tt>TimeUnit</tt> represents time durations at a given unit of
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* granularity and provides utility methods to convert across units,
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* and to perform timing and delay operations in these units. A
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* <tt>TimeUnit</tt> does not maintain time information, but only
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* helps organize and use time representations that may be maintained
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* separately across various contexts. A nanosecond is defined as one
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* thousandth of a microsecond, a microsecond as one thousandth of a
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* millisecond, a millisecond as one thousandth of a second, a minute
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* as sixty seconds, an hour as sixty minutes, and a day as twenty four
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* hours.
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*
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* <p>A <tt>TimeUnit</tt> is mainly used to inform time-based methods
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* how a given timing parameter should be interpreted. For example,
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* the following code will timeout in 50 milliseconds if the {@link
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* java.util.concurrent.locks.Lock lock} is not available:
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*
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* <pre> Lock lock = ...;
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* if ( lock.tryLock(50L, TimeUnit.MILLISECONDS) ) ...
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* </pre>
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* while this code will timeout in 50 seconds:
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* <pre>
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* Lock lock = ...;
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* if ( lock.tryLock(50L, TimeUnit.SECONDS) ) ...
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* </pre>
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*
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* Note however, that there is no guarantee that a particular timeout
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* implementation will be able to notice the passage of time at the
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* same granularity as the given <tt>TimeUnit</tt>.
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*
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* @since 1.5
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* @author Doug Lea
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*/
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public enum TimeUnit {
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NANOSECONDS {
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public long toNanos(long d) { return d; }
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public long toMicros(long d) { return d/(C1/C0); }
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public long toMillis(long d) { return d/(C2/C0); }
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public long toSeconds(long d) { return d/(C3/C0); }
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public long toMinutes(long d) { return d/(C4/C0); }
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public long toHours(long d) { return d/(C5/C0); }
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public long toDays(long d) { return d/(C6/C0); }
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public long convert(long d, TimeUnit u) { return u.toNanos(d); }
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int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
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},
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MICROSECONDS {
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public long toNanos(long d) { return x(d, C1/C0, MAX/(C1/C0)); }
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public long toMicros(long d) { return d; }
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public long toMillis(long d) { return d/(C2/C1); }
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public long toSeconds(long d) { return d/(C3/C1); }
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public long toMinutes(long d) { return d/(C4/C1); }
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public long toHours(long d) { return d/(C5/C1); }
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public long toDays(long d) { return d/(C6/C1); }
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public long convert(long d, TimeUnit u) { return u.toMicros(d); }
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int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
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},
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MILLISECONDS {
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public long toNanos(long d) { return x(d, C2/C0, MAX/(C2/C0)); }
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public long toMicros(long d) { return x(d, C2/C1, MAX/(C2/C1)); }
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public long toMillis(long d) { return d; }
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public long toSeconds(long d) { return d/(C3/C2); }
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public long toMinutes(long d) { return d/(C4/C2); }
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public long toHours(long d) { return d/(C5/C2); }
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public long toDays(long d) { return d/(C6/C2); }
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public long convert(long d, TimeUnit u) { return u.toMillis(d); }
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int excessNanos(long d, long m) { return 0; }
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},
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SECONDS {
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public long toNanos(long d) { return x(d, C3/C0, MAX/(C3/C0)); }
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public long toMicros(long d) { return x(d, C3/C1, MAX/(C3/C1)); }
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public long toMillis(long d) { return x(d, C3/C2, MAX/(C3/C2)); }
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public long toSeconds(long d) { return d; }
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public long toMinutes(long d) { return d/(C4/C3); }
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public long toHours(long d) { return d/(C5/C3); }
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public long toDays(long d) { return d/(C6/C3); }
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public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
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int excessNanos(long d, long m) { return 0; }
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},
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MINUTES {
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public long toNanos(long d) { return x(d, C4/C0, MAX/(C4/C0)); }
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public long toMicros(long d) { return x(d, C4/C1, MAX/(C4/C1)); }
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public long toMillis(long d) { return x(d, C4/C2, MAX/(C4/C2)); }
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public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
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public long toMinutes(long d) { return d; }
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public long toHours(long d) { return d/(C5/C4); }
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public long toDays(long d) { return d/(C6/C4); }
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public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
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int excessNanos(long d, long m) { return 0; }
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},
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HOURS {
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public long toNanos(long d) { return x(d, C5/C0, MAX/(C5/C0)); }
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public long toMicros(long d) { return x(d, C5/C1, MAX/(C5/C1)); }
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public long toMillis(long d) { return x(d, C5/C2, MAX/(C5/C2)); }
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public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
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public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
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public long toHours(long d) { return d; }
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public long toDays(long d) { return d/(C6/C5); }
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public long convert(long d, TimeUnit u) { return u.toHours(d); }
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int excessNanos(long d, long m) { return 0; }
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},
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DAYS {
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public long toNanos(long d) { return x(d, C6/C0, MAX/(C6/C0)); }
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public long toMicros(long d) { return x(d, C6/C1, MAX/(C6/C1)); }
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public long toMillis(long d) { return x(d, C6/C2, MAX/(C6/C2)); }
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public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
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public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
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public long toHours(long d) { return x(d, C6/C5, MAX/(C6/C5)); }
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public long toDays(long d) { return d; }
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public long convert(long d, TimeUnit u) { return u.toDays(d); }
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int excessNanos(long d, long m) { return 0; }
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};
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// Handy constants for conversion methods
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static final long C0 = 1L;
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static final long C1 = C0 * 1000L;
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static final long C2 = C1 * 1000L;
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static final long C3 = C2 * 1000L;
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static final long C4 = C3 * 60L;
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static final long C5 = C4 * 60L;
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static final long C6 = C5 * 24L;
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static final long MAX = Long.MAX_VALUE;
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/**
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* Scale d by m, checking for overflow.
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* This has a short name to make above code more readable.
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*/
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static long x(long d, long m, long over) {
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if (d > over) return Long.MAX_VALUE;
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if (d < -over) return Long.MIN_VALUE;
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return d * m;
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}
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// To maintain full signature compatibility with 1.5, and to improve the
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// clarity of the generated javadoc (see 6287639: Abstract methods in
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// enum classes should not be listed as abstract), method convert
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// etc. are not declared abstract but otherwise act as abstract methods.
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/**
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* Convert the given time duration in the given unit to this
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* unit. Conversions from finer to coarser granularities
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* truncate, so lose precision. For example converting
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* <tt>999</tt> milliseconds to seconds results in
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* <tt>0</tt>. Conversions from coarser to finer granularities
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* with arguments that would numerically overflow saturate to
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* <tt>Long.MIN_VALUE</tt> if negative or <tt>Long.MAX_VALUE</tt>
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* if positive.
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*
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* <p>For example, to convert 10 minutes to milliseconds, use:
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* <tt>TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)</tt>
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*
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* @param sourceDuration the time duration in the given <tt>sourceUnit</tt>
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* @param sourceUnit the unit of the <tt>sourceDuration</tt> argument
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* @return the converted duration in this unit,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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*/
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public long convert(long sourceDuration, TimeUnit sourceUnit) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>NANOSECONDS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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*/
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public long toNanos(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>MICROSECONDS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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*/
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public long toMicros(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>MILLISECONDS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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*/
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public long toMillis(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>SECONDS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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*/
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public long toSeconds(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>MINUTES.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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* @since 1.6
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*/
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public long toMinutes(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>HOURS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration,
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* or <tt>Long.MIN_VALUE</tt> if conversion would negatively
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* overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
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* @see #convert
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* @since 1.6
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*/
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public long toHours(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Equivalent to <tt>DAYS.convert(duration, this)</tt>.
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* @param duration the duration
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* @return the converted duration
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* @see #convert
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* @since 1.6
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*/
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public long toDays(long duration) {
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throw new AbstractMethodError();
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}
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/**
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* Utility to compute the excess-nanosecond argument to wait,
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* sleep, join.
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* @param d the duration
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* @param m the number of milliseconds
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* @return the number of nanoseconds
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*/
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abstract int excessNanos(long d, long m);
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/**
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* Performs a timed <tt>Object.wait</tt> using this time unit.
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* This is a convenience method that converts timeout arguments
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* into the form required by the <tt>Object.wait</tt> method.
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*
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* <p>For example, you could implement a blocking <tt>poll</tt>
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* method (see {@link BlockingQueue#poll BlockingQueue.poll})
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* using:
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*
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* <pre> public synchronized Object poll(long timeout, TimeUnit unit) throws InterruptedException {
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* while (empty) {
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* unit.timedWait(this, timeout);
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* ...
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* }
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* }</pre>
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*
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* @param obj the object to wait on
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* @param timeout the maximum time to wait. If less than
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* or equal to zero, do not wait at all.
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* @throws InterruptedException if interrupted while waiting.
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* @see Object#wait(long, int)
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*/
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public void timedWait(Object obj, long timeout)
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throws InterruptedException {
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if (timeout > 0) {
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long ms = toMillis(timeout);
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int ns = excessNanos(timeout, ms);
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obj.wait(ms, ns);
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}
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}
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/**
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* Performs a timed <tt>Thread.join</tt> using this time unit.
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* This is a convenience method that converts time arguments into the
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* form required by the <tt>Thread.join</tt> method.
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* @param thread the thread to wait for
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* @param timeout the maximum time to wait. If less than
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* or equal to zero, do not wait at all.
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* @throws InterruptedException if interrupted while waiting.
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* @see Thread#join(long, int)
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*/
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public void timedJoin(Thread thread, long timeout)
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throws InterruptedException {
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if (timeout > 0) {
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long ms = toMillis(timeout);
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int ns = excessNanos(timeout, ms);
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thread.join(ms, ns);
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}
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}
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/**
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* Performs a <tt>Thread.sleep</tt> using this unit.
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* This is a convenience method that converts time arguments into the
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* form required by the <tt>Thread.sleep</tt> method.
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* @param timeout the minimum time to sleep. If less than
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* or equal to zero, do not sleep at all.
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* @throws InterruptedException if interrupted while sleeping.
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* @see Thread#sleep
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*/
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public void sleep(long timeout) throws InterruptedException {
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if (timeout > 0) {
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long ms = toMillis(timeout);
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int ns = excessNanos(timeout, ms);
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Thread.sleep(ms, ns);
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}
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}
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}
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