net.openhft.chronicle.bytes

Class DistributedUniqueTimeProvider

java.lang.Object

net.openhft.chronicle.core.io.SimpleCloseable

net.openhft.chronicle.bytes.DistributedUniqueTimeProvider

All Implemented Interfaces:

Closeable, AutoCloseable, net.openhft.chronicle.core.io.ManagedCloseable, net.openhft.chronicle.core.io.Monitorable, net.openhft.chronicle.core.io.QueryCloseable, net.openhft.chronicle.core.io.ReferenceOwner, net.openhft.chronicle.core.time.TimeProvider

public class DistributedUniqueTimeProvider
extends net.openhft.chronicle.core.io.SimpleCloseable
implements net.openhft.chronicle.core.time.TimeProvider, net.openhft.chronicle.core.io.Monitorable

Provides unique timestamps across multiple systems by incorporating a host identifier into the timestamp, for microsecond and nanosecond resolution timestamps. This class is particularly useful in distributed systems where clock synchronization and uniqueness across hosts are critical. It implements TimeProvider.

NOTE: currentTimeMillis() is not unique, it is just a call to the underlying provider as there isn't enough resolution to include the hostId.

Each timestamp generated is guaranteed to be unique across all hosts participating in the system. The class uses a file-based mechanism to ensure that timestamps are not only unique across restarts but also across different JVM instances.

Field Summary

Fields inherited from interface net.openhft.chronicle.core.io.ReferenceOwner

INIT, TMP

Method Summary

Modifier and Type	Method and Description
long	currentTimeMicros() This method returns a unique, monotonically increasing microsecond timestamp where the lowest two digits of the microseconds is the hostId, ensuring uniqueness across different hosts.
long	currentTimeMillis() NOTE: Calls to this method do not produce unique timestamps, rather just calls the underlying provider.
long	currentTimeNanos() This method returns a unique, monotonically increasing nanosecond timestamp.
static DistributedUniqueTimeProvider	forHostId(int hostId) Creates a new instance of DistributedUniqueTimeProvider for a specified hostId.
DistributedUniqueTimeProvider	hostId(int hostId) Sets the hostId of the DistributedUniqueTimeProvider.
static long	hostIdFor(long timestampWithHostId) Extract the hostId from the timestampWithHostId
static DistributedUniqueTimeProvider	instance() Provides a singleton instance of DistributedUniqueTimeProvider using the default hostId.
protected void	performClose()
DistributedUniqueTimeProvider	provider(net.openhft.chronicle.core.time.TimeProvider provider) Sets the TimeProvider of the DistributedUniqueTimeProvider.
static long	timestampFor(long timestampWithHostId) Extract the timestamp in nanoseconds from the timestampWithHostId
void	unmonitor()

Methods inherited from class net.openhft.chronicle.core.io.SimpleCloseable

close, isClosed

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.openhft.chronicle.core.io.Monitorable

unmonitor

Methods inherited from interface net.openhft.chronicle.core.io.ReferenceOwner

referenceId, referenceName, temporary

Methods inherited from interface net.openhft.chronicle.core.io.ManagedCloseable

createdHere, throwExceptionIfClosed, warnAndCloseIfNotClosed

Methods inherited from interface net.openhft.chronicle.core.io.Closeable

closeQuietly, closeQuietly

Methods inherited from interface net.openhft.chronicle.core.io.QueryCloseable

isClosing

Method Detail

instance

public static DistributedUniqueTimeProvider instance()

Provides a singleton instance of DistributedUniqueTimeProvider using the default hostId. This method is thread-safe and uses lazy initialization.

Returns:

the single, shared instance of DistributedUniqueTimeProvider

forHostId

public static DistributedUniqueTimeProvider forHostId(int hostId)

Creates a new instance of DistributedUniqueTimeProvider for a specified hostId. This is useful in scenarios where multiple instances are required, each with a different hostId.

Parameters:

hostId - the host identifier for which the time provider is to be created, must be non-negative

Returns:

a new instance of DistributedUniqueTimeProvider configured with the given hostId

timestampFor

public static long timestampFor(long timestampWithHostId)

Extract the timestamp in nanoseconds from the timestampWithHostId

Parameters:

timestampWithHostId - to extract from

Returns:

the timestamp

hostIdFor

public static long hostIdFor(long timestampWithHostId)

Extract the hostId from the timestampWithHostId

Parameters:

timestampWithHostId - to extract from

Returns:

the hostId

performClose

protected void performClose()

Overrides:

performClose in class net.openhft.chronicle.core.io.SimpleCloseable

hostId

public DistributedUniqueTimeProvider hostId(int hostId)

Sets the hostId of the DistributedUniqueTimeProvider. The hostId is used to create unique timestamps across different hosts.

Parameters:

hostId - The host identifier, must be non-negative.

Returns:

A reference to the current DistributedUniqueTimeProvider instance with the updated hostId.

Throws:

IllegalArgumentException - if the provided hostId is negative.

provider

public DistributedUniqueTimeProvider provider(net.openhft.chronicle.core.time.TimeProvider provider)

Sets the TimeProvider of the DistributedUniqueTimeProvider. The TimeProvider is responsible for providing the current time in nanoseconds.

Parameters:

provider - The TimeProvider instance to be used for fetching the current time.

Returns:

A reference to the current DistributedUniqueTimeProvider instance with the updated TimeProvider.

currentTimeMillis

public long currentTimeMillis()

NOTE: Calls to this method do not produce unique timestamps, rather just calls the underlying provider.

Use currentTimeMicros() or currentTimeNanos() to generate unique timestamps, or use UniqueMicroTimeProvider.currentTimeMillis() to generate unique timestamps.

Specified by:

currentTimeMillis in interface net.openhft.chronicle.core.time.TimeProvider

Returns:

Ordinary millisecond timestamp

currentTimeMicros

public long currentTimeMicros()
                       throws IllegalStateException

This method returns a unique, monotonically increasing microsecond timestamp where the lowest two digits of the microseconds is the hostId, ensuring uniqueness across different hosts.

Specified by:

currentTimeMicros in interface net.openhft.chronicle.core.time.TimeProvider

Returns:

the timestamps with hostId as a long

Throws:

IllegalStateException

currentTimeNanos

public long currentTimeNanos()
                      throws IllegalStateException

This method returns a unique, monotonically increasing nanosecond timestamp. The lowest two digits of the nanoseconds is the hostId, providing uniqueness across different hosts.

Specified by:

currentTimeNanos in interface net.openhft.chronicle.core.time.TimeProvider

Returns:

the timestamps with hostId as a long

Throws:

IllegalStateException

unmonitor

public void unmonitor()

Specified by:

unmonitor in interface net.openhft.chronicle.core.io.Monitorable