org.glassfish.jersey.server.internal.monitoring

Class UniformTimeReservoir

java.lang.Object

org.glassfish.jersey.server.internal.monitoring.UniformTimeReservoir

All Implemented Interfaces:

TimeReservoir<java.lang.Long>

class UniformTimeReservoir
extends java.lang.Object
implements TimeReservoir<java.lang.Long>

A random sampling reservoir of a stream of longs. Uses Vitter's Algorithm R to produce a statistically representative sample.

See Also:

Random Sampling with a Reservoir, https://github.com/dropwizard/metrics

Field Summary

Fields

Modifier and Type	Field and Description
private static int	BITS_PER_LONG
private java.util.concurrent.atomic.AtomicLong	count
private static int	DEFAULT_SIZE
private long	startTime
private java.util.concurrent.TimeUnit	startTimeUnit
private java.util.concurrent.atomic.AtomicLongArray	values

Constructor Summary

Constructors

Constructor and Description
UniformTimeReservoir(int size, long startTime, java.util.concurrent.TimeUnit startTimeUnit) Creates a new UniformTimeReservoir instance.
UniformTimeReservoir(long startTime, java.util.concurrent.TimeUnit startTimeUnit) Creates a new UniformTimeReservoir instance of 1024 elements, which offers a 99.9% confidence level with a 5% margin of error assuming a normal distribution.

Method Summary

Modifier and Type	Method and Description
UniformTimeSnapshot	getSnapshot(long time, java.util.concurrent.TimeUnit timeUnit) Returns a snapshot of the reservoir's values at given time or newer.
long	interval(java.util.concurrent.TimeUnit timeUnit) The time interval this reservoir stores data of.
private static long	nextLong(long n) Get a pseudo-random long uniformly between 0 and n-1.
int	size(long time, java.util.concurrent.TimeUnit timeUnit) Returns the number of values recorded at given time or newer.
void	update(java.lang.Long value, long time, java.util.concurrent.TimeUnit timeUnit) Adds a new recorded value to the reservoir bound to a given time.

Methods inherited from class java.lang.Object

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

Field Detail

startTime

private final long startTime

startTimeUnit

private final java.util.concurrent.TimeUnit startTimeUnit

DEFAULT_SIZE

private static final int DEFAULT_SIZE

See Also:

Constant Field Values

BITS_PER_LONG

private static final int BITS_PER_LONG

See Also:

Constant Field Values

count

private final java.util.concurrent.atomic.AtomicLong count

values

private final java.util.concurrent.atomic.AtomicLongArray values

Constructor Detail

UniformTimeReservoir

public UniformTimeReservoir(long startTime,
                            java.util.concurrent.TimeUnit startTimeUnit)

Creates a new UniformTimeReservoir instance of 1024 elements, which offers a 99.9% confidence level with a 5% margin of error assuming a normal distribution.

Parameters:

startTime - The start time

startTimeUnit - The start time unit

UniformTimeReservoir

public UniformTimeReservoir(int size,
                            long startTime,
                            java.util.concurrent.TimeUnit startTimeUnit)

Creates a new UniformTimeReservoir instance.

Parameters:

size - the number of samples to keep in the sampling reservoir

startTime - The start time

startTimeUnit - The start time unit

Method Detail

size

public int size(long time,
                java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: TimeReservoir

Returns the number of values recorded at given time or newer. It may not be supported to return a size in past due to performance optimizations.

Specified by:

size in interface TimeReservoir<java.lang.Long>

Parameters:

time - The time to get the size for

timeUnit - Time unit of the provided time

Returns:

the number of values recorded for given time or newer

update

public void update(java.lang.Long value,
                   long time,
                   java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: TimeReservoir

Adds a new recorded value to the reservoir bound to a given time.

Specified by:

update in interface TimeReservoir<java.lang.Long>

Parameters:

value - a new recorded value

time - The time the recorded value occurred at

timeUnit - Time unit of the provided time

nextLong

private static long nextLong(long n)

Get a pseudo-random long uniformly between 0 and n-1. Stolen from Random.nextInt().

Parameters:

n - the bound

Returns:

a value select randomly from the range [0..n).

getSnapshot

public UniformTimeSnapshot getSnapshot(long time,
                                       java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: TimeReservoir

Returns a snapshot of the reservoir's values at given time or newer. It may not be supported to return a snapshot in past due to performance optimizations.

Specified by:

getSnapshot in interface TimeReservoir<java.lang.Long>

Parameters:

time - The time for which to get the snapshot

timeUnit - Time unit of the provided time

Returns:

a snapshot of the reservoir's values for given time or newer

interval

public long interval(java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: TimeReservoir

The time interval this reservoir stores data of.

Specified by:

interval in interface TimeReservoir<java.lang.Long>

Parameters:

timeUnit - The time unit in which to get the interval

Returns:

The time interval of this time reservoir