Package com.github.f4b6a3.uuid.strategy.timestamp

Class DefaultTimestampStrategy

java.lang.Object

com.github.f4b6a3.uuid.strategy.timestamp.DefaultTimestampStrategy

All Implemented Interfaces:

TimestampStrategy

public final class DefaultTimestampStrategy
extends Object
implements TimestampStrategy

Strategy that provides the current timestamp. This is an implementation of TimestampStrategy that provides millisecond resolution. The timestamp resolution is simulated by adding the next value of a counter that is incremented at every call to the method TimestampStrategy.getTimestamp(). The counter's range is from 0 to 9,999, that is, the number of 100-nanosecond intervals per millisecond. The counter is initialized with a random number between 0 and 255 to void duplicates in the case of multiple time-based generators running in parallel. ### RFC-4122 - 4.2.1.2. System Clock Resolution (P1) The timestamp is generated from the system time, whose resolution may be less than the resolution of the UUID timestamp. (P2) If UUIDs do not need to be frequently generated, the timestamp can simply be the system time multiplied by the number of 100-nanosecond intervals per system time interval. (P3) If a system overruns the generator by requesting too many UUIDs within a single system time interval, the UUID service MUST either return an error, or stall the UUID generator until the system clock catches up. (P4) A high resolution timestamp can be simulated by keeping a COUNT of the number of UUIDs that have been generated with the same value of the system time, and using it to construct the low order bits of the timestamp. The COUNT will range between zero and the number of 100-nanosecond intervals per system time interval. (P5) Note: If the processors overrun the UUID generation frequently, additional node identifiers can be allocated to the system, which will permit higher speed allocation by making multiple UUIDs potentially available for each time stamp value.

Field Summary

Fields

Modifier and Type	Field	Description
protected static int	COUNTER_MAX
protected static int	COUNTER_MIN

Constructor Summary

Constructors

Constructor	Description
DefaultTimestampStrategy()

Method Summary

Modifier and Type	Method	Description
protected long	getNextCounter(long timestamp)	Get the next counter value.
long	getTimestamp()	Get the next current timestamp.

Methods inherited from class java.lang.Object

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

Field Detail

COUNTER_MIN

protected static final int COUNTER_MIN

See Also:

Constant Field Values

COUNTER_MAX

protected static final int COUNTER_MAX

See Also:

Constant Field Values

Constructor Detail

DefaultTimestampStrategy

public DefaultTimestampStrategy()

Method Detail

getTimestamp

public long getTimestamp()

Get the next current timestamp. The timestamp has millisecond accuracy. An internal counter is added to the timestamp to simulate the resolution of 100-nanoseconds.

Specified by:

getTimestamp in interface TimestampStrategy

Returns:

the current timestamp

Throws:

UuidCreatorException - an overrun exception if more than 10 thousand UUIDs are requested within the same millisecond

getNextCounter

protected long getNextCounter(long timestamp)

Get the next counter value.

Parameters:

timestamp - a timestamp

Returns:

the next counter value

Throws:

UuidCreatorException - an overrun exception if more than 10 thousand UUIDs are requested within the same millisecond