net.openhft.chronicle.core.time

Enum SystemTimeProvider

java.lang.Object

java.lang.Enum<SystemTimeProvider>

net.openhft.chronicle.core.time.SystemTimeProvider

All Implemented Interfaces:

Serializable, Comparable<SystemTimeProvider>, TimeProvider

public enum SystemTimeProvider
extends Enum<SystemTimeProvider>
implements TimeProvider

Synthesises a nanosecond wall clock from the system clock.

This provider keeps a running delta between System.nanoTime() and System.currentTimeMillis(). The delta is adjusted whenever the calculated estimate falls behind the millisecond tick or drifts more than one millisecond ahead. This keeps the returned value monotonic and within roughly a millisecond of the wall clock.

 System.currentTimeMillis : |----|----|----|
 System.nanoTime          : --------->
                             ^
                             | delta
 currentTimeNanos()         : --------->
 

Typical call latency is about 40 ns on modern hardware.

Enum Constant Summary

Enum Constants

Enum Constant and Description
INSTANCE

Field Summary

Fields

Modifier and Type	Field and Description
static TimeProvider	CLOCK

Method Summary

Modifier and Type	Method and Description
long	currentTimeMicros() Returns the current wall-clock time in microseconds.
long	currentTimeMillis() Returns the current wall-clock time in milliseconds.
long	currentTimeNanos() Returns a nanosecond timestamp derived from System.nanoTime() and adjusted by delta.
static SystemTimeProvider	valueOf(String name) Returns the enum constant of this type with the specified name.
static SystemTimeProvider[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

INSTANCE

public static final SystemTimeProvider INSTANCE

Field Detail

CLOCK

public static TimeProvider CLOCK

Method Detail

values

public static SystemTimeProvider[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (SystemTimeProvider c : SystemTimeProvider.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static SystemTimeProvider valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

currentTimeMillis

public long currentTimeMillis()

Returns the current wall-clock time in milliseconds.

Specified by:

currentTimeMillis in interface TimeProvider

Returns:

milliseconds since the Unix epoch

currentTimeMicros

public long currentTimeMicros()

Returns the current wall-clock time in microseconds.

Specified by:

currentTimeMicros in interface TimeProvider

Returns:

microseconds since the Unix epoch

currentTimeNanos

public long currentTimeNanos()

Returns a nanosecond timestamp derived from System.nanoTime() and adjusted by delta. The result is monotonic and kept within one millisecond of System.currentTimeMillis().

Specified by:

currentTimeNanos in interface TimeProvider

Returns:

the current time in nanoseconds since the Unix epoch