Package com.palantir.tritium.metrics.registry

Class LockFreeExponentiallyDecayingReservoir

java.lang.Object

com.palantir.tritium.metrics.registry.LockFreeExponentiallyDecayingReservoir

All Implemented Interfaces:

com.codahale.metrics.Reservoir

@Beta
public final class LockFreeExponentiallyDecayingReservoir
extends java.lang.Object
implements com.codahale.metrics.Reservoir

LockFreeExponentiallyDecayingReservoir is based closely on the codahale ExponentiallyDecayingReservoir.java, however it provides looser guarantees while completely avoiding locks. This implementation is being contributed upstream: metrics#1656 Looser guarantees:

• Updates which occur concurrently with rescaling may be discarded if the orphaned state node is updated after rescale has replaced it. This condition has a greater probability as the rescale interval is reduced due to the increased frequency of rescaling. rescaleThresholdNanos values below 30 seconds are not recommended.
• Given a small rescale threshold, updates may attempt to rescale into a new bucket, but lose the CAS race and update into a newer bucket than expected. In these cases the measurement weight is reduced accordingly.
• In the worst case, all concurrent threads updating the reservoir may attempt to rescale rather than a single thread holding an exclusive write lock. It's expected that the configuration is set such that rescaling is substantially less common than updating at peak load. Even so, when size is reasonably small it can be more efficient to rescale than to park and context switch.

See ExponentiallyDecayingReservoir Copyright 2010-2012 Coda Hale and Yammer, Inc. Licensed under the Apache License, Version 2.0. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LockFreeExponentiallyDecayingReservoir.Builder	By default this uses a size of 1028 elements, which offers a 99.9% confidence level with a 5% margin of error assuming a normal distribution, and an alpha factor of 0.015, which heavily biases the reservoir to the past 5 minutes of measurements.

Method Summary

Modifier and Type	Method	Description
static LockFreeExponentiallyDecayingReservoir.Builder	builder()
com.codahale.metrics.Snapshot	getSnapshot()
int	size()
void	update(long value)

Methods inherited from class java.lang.Object

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

Method Detail

size

public int size()

Specified by:

size in interface com.codahale.metrics.Reservoir

update

public void update(long value)

Specified by:

update in interface com.codahale.metrics.Reservoir

getSnapshot

public com.codahale.metrics.Snapshot getSnapshot()

Specified by:

getSnapshot in interface com.codahale.metrics.Reservoir

builder

public static LockFreeExponentiallyDecayingReservoir.Builder builder()