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Utils (Drools 4.0.0.11754MR2 API) - JBoss RULES 4.0.0.11754MR2 API 英文版文档

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org.drools.util.concurrent.locks
Class Utils

java.lang.Object
  org.drools.util.concurrent.locks.Utils

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public final class Utils
extends Object

This class groups together the functionality of java.util.concurrent that cannot be fully and reliably implemented in backport, but for which some form of emulation is possible.

Currently, this class contains methods related to nanosecond-precision timing, particularly via the nanoTime() method. To measure time accurately, this method by default uses java.sun.Perf on JDK1.4.2 and it falls back to System.currentTimeMillis on earlier JDKs.

Version:

1.0

Author:

Dawid Kurzyniec

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Method Summary
static Object[]	collectionToArray(Collection c)
static Object[]	collectionToArray(Collection c, Object[] a)
static long	nanoTime()           Returns the current value of the most precise available system timer, in nanoseconds.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Method Detail

nanoTime

public static long nanoTime()

Returns the current value of the most precise available system timer, in nanoseconds. This method can only be used to measure elapsed time and is not related to any other notion of system or wall-clock time. The value returned represents nanoseconds since some fixed but arbitrary time (perhaps in the future, so values may be negative). This method provides nanosecond precision, but not necessarily nanosecond accuracy. No guarantees are made about how frequently values change. Differences in successive calls that span greater than approximately 292 years (2^63 nanoseconds) will not accurately compute elapsed time due to numerical overflow.

Implementation note:By default, this method uses sun.misc.Perf on Java 1.4.2, and falls back to System.currentTimeMillis() emulation on earlier JDKs. Custom timer can be provided via the system property edu.emory.mathcs.backport.java.util.concurrent.NanoTimerProvider. The value of the property should name a class implementing NanoTimer interface.

Note: on JDK 1.4.2, sun.misc.Perf timer seems to have resolution of the order of 1 microsecond, measured on Linux.

Returns:

The current value of the system timer, in nanoseconds.

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collectionToArray

public static Object[] collectionToArray(Collection c)

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collectionToArray

public static Object[] collectionToArray(Collection c,
                                         Object[] a)

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