net.openhft.chronicle.core.time

Class UniqueMicroTimeProvider

java.lang.Object

net.openhft.chronicle.core.time.UniqueMicroTimeProvider

All Implemented Interfaces:

TimeProvider

public class UniqueMicroTimeProvider
extends Object
implements TimeProvider

A TimeProvider implementation that ensures unique timestamps across threads within a single process. It provides time in milliseconds, microseconds, and nanoseconds while ensuring that the time value is unique even across rapid successive calls.

This implementation is particularly useful in environments where unique time stamps are critical and the application might request them at a high rate.

Each call spins in a compare-and-set loop. After a failed attempt the code invokes Jvm.nanoPause() as a short back-off before retrying. This reduces contention when multiple threads compete to update the timestamp.

See the white paper "Unique IDs at 10 M/s" at https://chronicle.software/wp-content/uploads/Unique-IDs-at-10M_s.pdf for background on the algorithm.

Field Summary

Fields

Modifier and Type	Field and Description
static UniqueMicroTimeProvider	INSTANCE

Constructor Summary

Constructors

Constructor and Description
UniqueMicroTimeProvider() Constructs a new UniqueMicroTimeProvider.

Method Summary

Modifier and Type	Method and Description
long	currentTimeMicros() Retrieves the current time in microseconds, ensuring uniqueness across threads.
long	currentTimeMillis() Retrieves the current time in milliseconds, ensuring uniqueness across threads.
long	currentTimeNanos() Retrieves the current time in nanoseconds, ensuring uniqueness across threads.
UniqueMicroTimeProvider	provider(TimeProvider provider) Sets the underlying time provider for this instance and initialises the last time value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

INSTANCE

public static final UniqueMicroTimeProvider INSTANCE

Constructor Detail

UniqueMicroTimeProvider

public UniqueMicroTimeProvider()

Constructs a new UniqueMicroTimeProvider.

This constructor initialises the provider with zero. Instances are typically used for testing as the class maintains the last issued time.

Method Detail

provider

public UniqueMicroTimeProvider provider(TimeProvider provider)

Sets the underlying time provider for this instance and initialises the last time value.

Parameters:

provider - delegate provider, not null

Returns:

this instance for chaining

currentTimeMillis

public long currentTimeMillis()

Retrieves the current time in milliseconds, ensuring uniqueness across threads.

Specified by:

currentTimeMillis in interface TimeProvider

Returns:

the current unique time in milliseconds since the epoch

currentTimeMicros

public long currentTimeMicros()

Retrieves the current time in microseconds, ensuring uniqueness across threads. It increments the time value by one microsecond if necessary to guarantee uniqueness.

Specified by:

currentTimeMicros in interface TimeProvider

Returns:

the current unique time in microseconds since the epoch

currentTimeNanos

public long currentTimeNanos()

Retrieves the current time in nanoseconds, ensuring uniqueness across threads. It adapts the nanosecond time based on the microsecond value to maintain unique timestamps.

Specified by:

currentTimeNanos in interface TimeProvider

Returns:

the current unique time in nanoseconds since the epoch