## File: README.md

Metrics
======= 
[](https://github.com/dropwizard/metrics/actions?query=workflow%3A%22Java+CI%22+branch%3Arelease%2F4.2.x)
[](https://maven-badges.herokuapp.com/maven-central/io.dropwizard.metrics/metrics-core/)
[](http://www.javadoc.io/doc/io.dropwizard.metrics/metrics-core)
[](https://gitpod.io/#https://github.com/dropwizard/metrics/tree/release/4.2.x)

*📈 Capturing JVM- and application-level metrics. So you know what's going on.*

For more information, please see [the documentation](https://metrics.dropwizard.io/)

### Versions

| Version | Source Branch                                                                    | Documentation                                 | Status            |
| ------- | -------------------------------------------------------------------------------- | --------------------------------------------- | ----------------- |
| <2.2.x  | -                                                                                | -                                             | 🔴 unmaintained   |
| 2.2.x   | -                                                                                | [Docs](https://metrics.dropwizard.io/2.2.0/)  | 🔴 unmaintained   |
| 3.0.x   | [release/3.0.x branch](https://github.com/dropwizard/metrics/tree/release/3.0.x) | [Docs](https://metrics.dropwizard.io/3.0.2/)  | 🔴 unmaintained   |
| 3.1.x   | [release/3.1.x branch](https://github.com/dropwizard/metrics/tree/release/3.1.x) | [Docs](https://metrics.dropwizard.io/3.1.0/)  | 🔴 unmaintained   |
| 3.2.x   | [release/3.2.x branch](https://github.com/dropwizard/metrics/tree/release/3.2.x) | [Docs](https://metrics.dropwizard.io/3.2.3/)  | 🔴 unmaintained   |
| 4.0.x   | [release/4.0.x branch](https://github.com/dropwizard/metrics/tree/release/4.0.x) | [Docs](https://metrics.dropwizard.io/4.0.6/)  | 🔴 unmaintained   |
| 4.1.x   | [release/4.1.x branch](https://github.com/dropwizard/metrics/tree/release/4.1.x) | [Docs](https://metrics.dropwizard.io/4.1.22/) | 🔴 unmaintained   |
| 4.2.x   | [release/4.2.x branch](https://github.com/dropwizard/metrics/tree/release/4.2.x) | [Docs](https://metrics.dropwizard.io/4.2.0/)  | 🟢 maintained     |
| 5.0.x   | [release/5.0.x branch](https://github.com/dropwizard/metrics/tree/release/5.0.x) | -                                             | 🟡 on pause       |

### Future development

New not-backward compatible features (for example, support for tags) will be implemented in a 5.x.x release. The release will have new Maven coordinates, a new package name and a backwards-incompatible API.

Source code for 5.x.x resides in the [release/5.0.x branch](https://github.com/dropwizard/metrics/tree/release/5.0.x).

License
-------

Copyright (c) 2010-2013 Coda Hale, Yammer.com, 2014-2021 Dropwizard Team

Published under Apache Software License 2.0, see LICENSE

---

## File: docs/source/about/contributors.rst

.. _about-contributors:

############
Contributors
############

Many, many thanks to:

* `Aaron Stockmeister <https://github.com/stockmaj>`_
* `Alan Woodward <https://github.com/romseygeek>`_
* `Aleksandr Podkutin <https://github.com/apodkutin>`_
* `Alex Lambert <https://github.com/alambert>`_
* `Alexander Eyers-Taylor <https://github.com/alexet>`_
* `Alexander Reelsen <https://github.com/spinscale>`_
* `Alexey Nezhdanov <https://github.com/snakeru>`_
* `Andreas Gebhardt <https://github.com/agebhar1>`_
* `Andrew Fitzgerald <https://github.com/fitzoh>`_
* `Andrey Rodionov <https://github.com/dernasherbrezon>`_ 
* `Anil V <https://github.com/avaitla>`_
* `Anthony Dahanne <https://github.com/anthonydahanne>`_
* `Antonin Stefanutti <https://github.com/astefanutti>`_
* `apirom9 <https://github.com/apirom9>`_
* `Artem Prigoda <https://github.com/arteam>`_
* `Ashley Sole <https://github.com/ashisamazin>`_
* `Bart Prokop <https://github.com/bartprokop>`_
* `Bartosz Krasiński <https://github.com/krasinski>`_
* `Basil James Whitehouse III <https://github.com/basil3whitehouse>`_
* `Ben Tatham <https://github.com/bentatham>`_
* `Benjamin Gehrels <https://github.com/BGehrels>`_
* `Bohdan Storozhuk <https://github.com/storozhukBM>`_
* `Brenden Matthews <https://github.com/brndnmtthws>`_
* `Brian  <https://github.com/codelotus>`_
* `Brian Roberts <https://github.com/flicken>`_
* `Bruce Mitchener <https://github.com/waywardmonkeys>`_
* `C. Scott Andreas <https://github.com/cscotta>`_
* `Carter Kozak <https://github.com/carterkozak>`_
* `cburroughs <https://github.com/cburroughs>`_
* `ceetav <https://github.com/ceetav>`_
* `Charles Care <https://github.com/ccare>`_
* `Chris Birchall <https://github.com/cb372>`_
* `Chris Rohr <https://github.com/chrisrohr>`_
* `Christopher Gray <https://github.com/chrisgray>`_
* `Christopher Swenson <https://github.com/swenson>`_
* `ciamac <https://github.com/ciamac>`_
* `Coda Hale <https://github.com/codahale>`_
* `Collin Van Dyck <https://github.com/collinvandyck>`_
* `Corentin Chary <https://github.com/iksaif>`_
* `Dag Liodden <https://github.com/daggerrz>`_
* `Dale Wijnand <https://github.com/dwijnand>`_
* `Dan Brown <https://github.com/jdanbrown>`_
* `Dan Everton <https://github.com/deverton>`_
* `Dan Revel <https://github.com/nopolabs>`_
* `Daniel James <https://github.com/dwhjames>`_
* `DarkJenum <https://github.com/DarkJenum>`_
* `David Hatanian <https://github.com/dhatanian>`_
* `David M. Karr <https://github.com/davidmichaelkarr>`_
* `David Pursehouse <https://github.com/dpursehouse>`_
* `David Schlosnagle <https://github.com/schlosna>`_
* `David Sutherland <https://github.com/djsutho>`_
* `Denny Abraham Cheriyan <https://github.com/dennyac>`_
* `Diwaker Gupta <https://github.com/diwakergupta>`_
* `Drew Stephens <https://github.com/dinomite>`_
* `Eduard Martinescu <https://github.com/Arvoreen>`_
* `Edwin Shin <https://github.com/eddies>`_
* `Erik van Oosten <https://github.com/erikvanoosten>`_
* `Erlend Hamnaberg <https://github.com/hamnis>`_
* `Evan Jones <https://github.com/evanj>`_
* `Fabien Renaud <https://github.com/fabienrenaud>`_
* `Fabrizio Cannizzo <https://github.com/smartrics>`_
* `Fokko Driesprong <https://github.com/Fokko>`_
* `François Beausoleil <https://github.com/francois>`_
* `Fred Deschenes <https://github.com/FredDeschenes>`_
* `g-fresh <https://github.com/g-fresh>`_
* `Gabor Arki <https://github.com/arkigabor>`_
* `George Spalding <https://github.com/georgespalding>`_
* `Gerolf Seitz <https://github.com/gseitz>`_
* `gilbode <https://github.com/gilbode>`_
* `goraxe <https://github.com/goraxe>`_
* `Greg Bowyer <https://github.com/GregBowyer>`_
* `Gregory Haase <https://github.com/ghaase>`_
* `Guillermo Calvo <https://github.com/guillermocalvo>`_
* `Gunnar Ahlberg <https://github.com/gunnarahlberg>`_
* `Henri Tremblay <https://github.com/henri-tremblay>`_
* `Hervé Boutemy <https://github.com/hboutemy>`_
* `Himangi Saraogi <https://github.com/hsaraogi>`_
* `ho3rexqj <https://github.com/ho3rexqj>`_
* `Hussein Elsayed <https://github.com/husseincoder>`_
* `Ian Strachan <https://github.com/ianestrachan>`_
* `Istvan Meszaros <https://github.com/IstvanM>`_
* `Ivan Dyedov <https://github.com/idyedov>`_
* `Jackson Davis <https://github.com/jcdavis>`_
* `James Burkhart <https://github.com/fourk>`_
* `James Casey <https://github.com/jamesc>`_
* `Jan-Helge Bergesen <https://github.com/jhberges>`_
* `Janne Sinivirta <https://github.com/vertti>`_
* `Jason A. Beranek <https://github.com/jasonberanek>`_
* `Jason Slagle <https://github.com/jmslagle>`_
* `Jason Whitlark <https://github.com/jwhitlark>`_
* `Jeff Hodges <https://github.com/jmhodges>`_
* `Jeff Klukas <https://github.com/jklukas>`_
* `Jeff Wartes <https://github.com/randomstatistic>`_
* `Jens Schauder <https://github.com/schauder>`_
* `Jesper Blomquist <https://github.com/jebl01>`_
* `Jesse Eichar <https://github.com/jesseeichar>`_
* `jkytomaki <https://github.com/jkytomaki>`_
* `Jochen Schalanda <https://github.com/joschi>`_
* `Joe Ellis <https://github.com/ellisjoe>`_
* `Joel Takvorian <https://github.com/jotak>`_
* `John Karp <https://github.com/john-karp>`_
* `John Wang <https://github.com/javasoze>`_
* `John Watson <https://github.com/jkwatson>`_
* `John-John Tedro <https://github.com/udoprog>`_
* `Jonathan Haber <https://github.com/jhaber>`_
* `Jordan Focht <https://github.com/jfocht>`_
* `Juha Syrjälä <https://github.com/jsyrjala>`_
* `Julio Lopez <https://github.com/julio-maginatics>`_
* `Justin Plock <https://github.com/jplock>`_
* `Jörg Fischer <https://github.com/g-fresh>`_
* `Kasa <https://github.com/raskasa>`_
* `KaseiFR <https://github.com/KaseiFR>`_
* `Keir Lawson <https://github.com/keirlawson>`_
* `Kevin Clark <https://github.com/kevinclark>`_
* `Kevin Herron <https://github.com/kevinherron>`_
* `Kevin Menard <https://github.com/nirvdrum>`_
* `Kevin Yeh <https://github.com/kyeah>`_
* `keze <https://github.com/keze>`_
* `konnik <https://github.com/konnik>`_
* `krasinski <https://github.com/krasinski>`_
* `Larry Shatzer, Jr. <https://github.com/larrys>`_
* `Luke Amdor <https://github.com/rubbish>`_
* `Magnus Reftel <https://github.com/reftel>`_
* `Mahesh Tiyyagura <https://github.com/tmahesh>`_
* `Marcin L <https://github.com/the-thing>`_
* `Mark Menard <https://github.com/MarkMenard>`_
* `Marlon Bernardes <https://github.com/marlonbernardes>`_
* `Martin Jöhren <https://github.com/matlockx>`_
* `Martin Traverso <https://github.com/martint>`_
* `Mateusz Zakarczemny <https://github.com/Matzz>`_
* `Matheus Cabral <https://github.com/mcgois>`_
* `Matt Abrams <https://github.com/abramsm>`_
* `Matt Veitas <https://github.com/mveitas>`_
* `Matthew Gilliard <https://github.com/mjg123>`_
* `Matthew O'Connor <https://github.com/oconnor0>`_
* `Matthias Wiedemann <https://github.com/mwiede>`_
* `Michael Golahi <https://github.com/mgolahi>`_
* `Michael Peyton Jones <https://github.com/michaelpj>`_
* `Michael Vorburger <https://github.com/vorburger>`_
* `Michał Minicki <https://github.com/martel>`_
* `Miikka Koskinen <https://github.com/miikka>`_
* `Mike Gilbode <https://github.com/gilbode>`_
* `Mike Minicki <https://github.com/martel>`_
* `Mårten Gustafson <https://github.com/chids>`_
* `Neil Prosser <https://github.com/neilprosser>`_
* `Nick Babcock <https://github.com/nickbabcock>`_
* `Nick Telford <https://github.com/nicktelford>`_
* `Nikolai Mazurkin <https://github.com/mazurkin>`_
* `Norbert Potocki <https://github.com/norbertpotocki>`_
* `Pablo Fernandez <https://github.com/fernandezpablo85>`_
* `Patryk Najda <https://github.com/patrox>`_
* `Paul Brown <https://github.com/prb>`_
* `Paul Doran <https://github.com/dorzey>`_
* `Paul Oliver <https://github.com/puzza007>`_
* `Paul Sanwald <https://github.com/pcsanwald>`_
* `Peter Steiner <https://github.com/pe-st>`_
* `Philip Dakowitz <https://github.com/philmtd>`_
* `Philip Helger <https://github.com/phax>`_
* `Philipp Hauer <https://github.com/phauer>`_
* `Rahul Ravindran <https://github.com/rahulravindran0108>`_
* `Raman Gupta <https://github.com/rocketraman>`_
* `Realbot <https://github.com/realbot>`_
* `Robby Walker <https://github.com/robbywalker>`_
* `Ron Klein <https://github.com/kleinron>`_
* `Ryan Campbell <https://github.com/recampbell>`_
* `Ryan McCrone <https://github.com/rwmccro>`_
* `Ryan Tenney <https://github.com/ryantenney>`_
* `saadmufti <https://github.com/saadmufti>`_
* `Sam Perman <https://github.com/samperman>`_
* `Sammy Chu <https://github.com/sammyhk>`_
* `Samy Dindane <https://github.com/Dinduks>`_
* `Scott Leberknight <https://github.com/sleberknight>`_
* `Sean Laurent <https://github.com/organicveggie>`_
* `Sebastian Lövdahl <https://github.com/slovdahl>`_
* `Sergey Nazarov <https://github.com/phearnot>`_
* `Sergio Escalante <https://github.com/sergioescala>`_
* `Shashank babu <https://github.com/shashank-babu>`_
* `Silvia Mandalà <https://github.com/simad>`_
* `sofax <https://github.com/sofax>`_
* `Stephen Souness <https://github.com/Sounie>`_
* `Steve Fosdal <https://github.com/sfosdal>`_
* `Steven Schlansker <https://github.com/stevenschlansker>`_
* `stockmaj <https://github.com/stockmaj>`_
* `Stuart Gunter <https://github.com/stuartgunter>`_
* `Tamas Cservenak <https://github.com/cstamas>`_
* `Thomas Cashman <https://github.com/tomcashman>`_
* `Tim Van Laer <https://github.com/timvlaer>`_
* `Tobias Bieniek <https://github.com/Turbo87>`_
* `Tobias Lidskog <https://github.com/tobli>`_
* `Tom Akehurst <https://github.com/tomakehurst>`_
* `Tom Golden <https://github.com/TomRK1089>`_
* `Tomas Celaya <https://github.com/tjcelaya>`_
* `Tomasz Guzik <https://github.com/tguzik>`_
* `Tomasz Nurkiewicz <https://github.com/nurkiewicz>`_
* `tomayoola <https://github.com/tomayoola>`_
* `tvleminckx <https://github.com/tvleminckx>`_
* `Ufuk Celebi <https://github.com/uce>`_
* `v-garki <https://github.com/v-garki>`_
* `Vadym Pechenoha <https://github.com/pechenoha>`_
* `Vasileios <https://github.com/vasilhsfoto>`_
* `Vladimir Bukhtoyarov <https://github.com/vladimir-bukhtoyarov>`_
* `Volker Fritzsch <https://github.com/volker>`_
* `Wolfgang Hoschek <https://github.com/whoschek>`_
* `Wolfgang Schell <https://github.com/jetztgradnet>`_
* `yeyangever <https://github.com/yeyangever>`_
* `Yuriy Badalyantc <https://github.com/LMnet>`_
* `Zach A. Thomas <https://github.com/zathomas>`_

---

## File: docs/source/about/index.rst

.. title:: About

.. _about:

#############
About Metrics
#############

.. toctree::
    :maxdepth: 1

    contributors
    release-notes

---

## File: docs/source/about/release-notes.rst

.. _release-notes:

#############
Release Notes
#############

Please refer to the `GitHub releases <https://github.com/dropwizard/metrics/releases>`_ for the latest releases of Dropwizard Metrics. 

.. _rel-4.0.0:

v4.0.0: Dec 24 2017
===================

* Compiled and targeted JDK8
* Support for running under JDK9 `#1236 <https://github.com/dropwizard/metrics/pull/1236>`_
* Move JMX reporting to the ``metrics-jmx`` module
* Add Bill of Materials for Metrics #1239 `#1239 <https://github.com/dropwizard/metrics/pull/1239>`_
* Used Java 8 Time API for data formatting
* Removed unnecessary reflection hacks for ``HealthCheckRegistry``
* Removed internal ``LongAdder``
* Removed internal ``ThreadLocalRandom``
* Optimized generating random numbers
* ``Timer.Context`` now implements ``AutoCloseable``
* Upgrade Jetty integration to Jetty 9.4
* Support tracking Jersey filters in Jersey resources `#1118 <https://github.com/dropwizard/metrics/pull/1239>`_
* Add ``ResponseMetered`` annotation for Jersey resources `#1186 <https://github.com/dropwizard/metrics/pull/1186>`_
* Add a method for timing non-throwing functions. `#1224 <https://github.com/dropwizard/metrics/pull/1224>`_
* Unnecessary clear operation for ChunkedAssociativeArray `#1211 <https://github.com/dropwizard/metrics/pull/1211>`_
* Add some common metric filters `#1210 <https://github.com/dropwizard/metrics/pull/1210>`_
* Add possibility to subclass Timer.Context `#1226 <https://github.com/dropwizard/metrics/pull/1226>`_

.. _rel-3.2.6:

v3.2.6: Dec 24 2017
===================

* Jetty9: unhandled response should be counted as 404 and not 200 `#1232 <https://github.com/dropwizard/metrics/pull/1232>`_
* Prevent NaN values when calculating mean `#1230 <https://github.com/dropwizard/metrics/pull/1230>`_
* Avoid NaN values in WeightedSnapshot `#1233 <https://github.com/dropwizard/metrics/pull/1233>`_

.. _rel-3.2.5:

v3.2.5: Sep 15 2017
===================

* [InstrumentedScheduledExecutorService] Fix the scheduledFixedDelay to call the correct method `#1192 <https://github.com/dropwizard/metrics/pull/1192>`_

.. _rel-3.2.4:

v3.2.4: Aug 24 2017
===================

* Fix GraphiteReporter rate reporting `#1167 <https://github.com/dropwizard/metrics/pull/1167>`_
* Remove non Jdk6 compatible letter from date pattern `#1163 <https://github.com/dropwizard/metrics/pull/1163>`_
* Fix uncaught CancellationException when stopping reporter `#1170 <https://github.com/dropwizard/metrics/pull/1170>`_

.. _rel-3.2.3:

v3.2.3: Jun 28 2017
===================

* Improve ``ScheduledReporter`` ``convertDurations`` precision `#1115 <https://github.com/dropwizard/metrics/pull/1115>`_
* Suppress all kinds of Throwables raised by ``report()`` `#1128 <https://github.com/dropwizard/metrics/pull/1128>`_
* ``ExponentiallyDecayingReservoir`` was giving incorrect values in the snapshot if the inactive period was too long `#1135 <https://github.com/dropwizard/metrics/pull/1135>`_
* Ability to get default metrics registry without an exception `#1140 <https://github.com/dropwizard/metrics/pull/1140>`_
* Ability to get default health check registry without an exception `#1152 <https://github.com/dropwizard/metrics/pull/1152>`_
* ``SlidingTimeWindowArrayReservoir`` as a fast alternative of ``SlidingTimeWindowReservoir`` `#1139 <https://github.com/dropwizard/metrics/pull/1139>`_
* Avoid a NPE in toString of ``HealthCheck.Result`` `#1141 <https://github.com/dropwizard/metrics/pull/1141>`_

.. _rel-3.1.5:

v3.1.5: Jun 2 2017
===================

* More robust lookup of ``ThreadLocal`` and ``LongAdder`` on JDK6 (e.g. WebLogic) `#1136 <https://github.com/dropwizard/metrics/pull/1136>`_

.. _rel-3.2.2:

v3.2.2: Mar 20 2017
===================

* Fix creating a uniform snapshot from a collection `#1111 <https://github.com/dropwizard/metrics/pull/1111>`_
* Register metrics defined at Resource level `#1105 <https://github.com/dropwizard/metrics/pull/1105>`_

.. _rel-3.2.1:

v3.2.1: Mar 10 2017
===================

* Support for shutting down the health check registry. `#1084 <https://github.com/dropwizard/metrics/pull/1084>`_
* Added support for the default shared health check registry name #1095 `#1095 <https://github.com/dropwizard/metrics/pull/1095>`_
* SharedMetricRegistries are now thread-safe. `#1094 <https://github.com/dropwizard/metrics/pull/1095>`_
* The size of the snapshot of a histogram is reported via JMX. `#1102 <https://github.com/dropwizard/metrics/pull/1102>`_
* Don't ignore the counter attribute for reporters. `#1090 <https://github.com/dropwizard/metrics/pull/1090>`_
* Added support for disabling attributes in ConsoleReporter. `#1092 <https://github.com/dropwizard/metrics/pull/1092>`_
* Rollbacked GraphiteSanitize to replacing whitespaces. `#1099 <https://github.com/dropwizard/metrics/pull/1099>`_

.. _rel-3.1.4:

v3.1.4: Mar 10 2017
===================

* Fix accidentally broken Graphite UDP reporter `#1100 <https://github.com/dropwizard/metrics/pull/1100>`_

.. _rel-3.2.0:

v3.2.0: Feb 24 2017
===================

* `GraphiteReporter` opens a new TCP connection when sending metrics instead of maintaining a persisted connection. `#1047 <https://github.com/dropwizard/metrics/pull/1047>`_
* `GraphiteReporter` retries DNS lookups in case of a lookup failure. `#1064 <https://github.com/dropwizard/metrics/pull/1064>`_
* `ScheduledReporter` suppresses all kind of exceptions raised by the `report` method. `#1049 <https://github.com/dropwizard/metrics/pull/1049>`_
* JDK's `ThreadLocalRandom` is now used by default. `#1052 <https://github.com/dropwizard/metrics/pull/1052>`_
* JDK's `LongAdder` is now used by default. `#1055 <https://github.com/dropwizard/metrics/pull/1055>`_
* Fixed a race condition bug in `ExponentiallyDecayingReservoir`. `#1033 <https://github.com/dropwizard/metrics/pull/1033>`_
* Fixed a long overflow bug in `SlidingTimeWindowReservoir`. `#1063 <https://github.com/dropwizard/metrics/pull/1063>`_
* `AdminServlet` supports CPU profiling. `#927 <https://github.com/dropwizard/metrics/pull/927>`_
* `GraphiteReporter` sanitizes metrics. `#938 <https://github.com/dropwizard/metrics/pull/938>`_
* Support for publishing `BigInteger` and `BigDecimal` metrics in `GraphiteReporter`. `#933 <https://github.com/dropwizard/metrics/pull/933>`_
* Support for publishing boolean metrics in `GraphiteReporter`. `#905 <https://github.com/dropwizard/metrics/pull/905>`_
* Added support for overriding the format of floating numbers in `GraphiteReporter`. `#1073 <https://github.com/dropwizard/metrics/pull/1073>`_
* Added support for disabling reporting of metric attributes. `#1048 <https://github.com/dropwizard/metrics/pull/1048>`_
* Reporters are more user friendly for managed environments like GAE or JEE. `#1018 <https://github.com/dropwizard/metrics/pull/1018>`_
* Support for setting a custom initial delay for reporters. `#999 <https://github.com/dropwizard/metrics/pull/999>`_
* Support for custom details in a result of a health check. `#663 <https://github.com/dropwizard/metrics/pull/663>`_
* Added a listener for health checks. `#1068 <https://github.com/dropwizard/metrics/pull/1068>`_
* Support for asynchronous health checks `#1077 <https://github.com/dropwizard/metrics/pull/1077>`_
* Health checks are reported as unhealthy on exceptions. `#783 <https://github.com/dropwizard/metrics/pull/783>`_
* Allow setting a custom prefix for Jetty's `InstrumentedQueuedThreadPool`. `#947 <https://github.com/dropwizard/metrics/pull/947>`_
* Allow setting custom prefix for Jetty's `QueuedThreadPool`. `#908 <https://github.com/dropwizard/metrics/pull/908>`_
* Added support for Jetty 9.3 and higher. `#1038 <https://github.com/dropwizard/metrics/pull/1038>`_
* Fixed instrumentation of Jetty9 async servlets. `#1074 <https://github.com/dropwizard/metrics/pull/1074>`_
* Added support for JCache/JSR 107 metrics. `#1010 <https://github.com/dropwizard/metrics/pull/1010>`_
* Added thread-safe getters for metrics with custom instantiations. `#1023 <https://github.com/dropwizard/metrics/pull/1023>`_
* Added an overload of `Timer#time` that takes a `Runnable`. `#989 <https://github.com/dropwizard/metrics/pull/989>`_
* Support extracting the request URI from wrapped requests in `HttpClientMetricNameStrategies`. `#947 <https://github.com/dropwizard/metrics/pull/947>`_
* Support for the log4j2 xml-based config. `#900 <https://github.com/dropwizard/metrics/pull/900>`_
* Internal `Striped64` doesn't depend on `sun.misc.Unsafe` anymore. `#966 <https://github.com/dropwizard/metrics/pull/966>`_
* Optimized creation of `UniformSnapshot`. `#970 <https://github.com/dropwizard/metrics/pull/970>`_
* Added a memory pool gauge to the JVM memory usage metrics. `#786 <https://github.com/dropwizard/metrics/pull/786>`_
* Added support for async servlets for `metric-servlet`. `#796 <https://github.com/dropwizard/metrics/pull/796>`_
* Opt-in default shared metric registry. `#801 <https://github.com/dropwizard/metrics/pull/801>`_
* Added support for patterns in MBean object names `#809 <https://github.com/dropwizard/metrics/pull/809>`_
* Allow a pluggable strategy for the name of the CSV files for `CsvReporter`. `#882 <https://github.com/dropwizard/metrics/pull/882>`_
* Upgraded to slf4j 1.22
* Upgraded to Jackson 2.6.6
* Upgraded to amqp-client 3.6.6
* Upgraded to httpclient 4.5.2
* Upgraded to log4j2 2.3
* Upgraded to logback 1.1.10

.. _rel-3.1.3:

v3.1.3: Feb 24 2017
===================

* `GraphiteReporter` opens a new TCP connection when sending metrics instead of maintaining a persisted connection. `#1036 <https://github.com/dropwizard/metrics/pull/1036>`_
* `GraphiteReporter` retries DNS lookups in case of a lookup failure. `#1064 <https://github.com/dropwizard/metrics/pull/1064>`_
* `ScheduledReporter` suppresses all kind of exceptions raised by the `report` method. `#1040 <https://github.com/dropwizard/metrics/pull/1040>`_
* JDK's `ThreadLocalRandom` is now used by default. `#1052 <https://github.com/dropwizard/metrics/pull/1052>`_
* JDK's `LongAdder` is now used by default. `#1055 <https://github.com/dropwizard/metrics/pull/1055>`_
* Fixed a race condition bug in `ExponentiallyDecayingReservoir`. `#1046 <https://github.com/dropwizard/metrics/pull/1046>`_
* Fixed a long overflow bug in `SlidingTimeWindowReservoir`. `#1072 <https://github.com/dropwizard/metrics/pull/1072>`_


.. _rel-3.1.0:

v3.1.0: Sen 10 2014
===================

https://groups.google.com/forum/#!topic/metrics-user/zwzHnMBcAX4

* Upgrade to Jetty 9.1 (metrics-jetty9, Jetty 9.0 module renamed to metrics-jetty9-legacy)
* Add log4j2 support (metrics-log4j2)
* Upgrade to Jersey2 (metrics-jersey2)
* Add httpasyncclient support (metrics-httpasyncclient)
* Changed maven groupId to io.dropwizard.metrics
* Enable Java8 builds on Travis, fix javadocs and disable some doclinting
* Fixing some compilation warnings about missing generics and varargs invocation
* Instrumentation for java.util.concurrent classes
* ExponentiallyDecayingReservoir: quantiles weighting
* Loosen type requirements for JmxAttributeGauge constructor
* SlidingWindowReservoir - ArrayOutOfBoundsException thrown if # of Reservoir examples exceeds Integer max value
* Classloader metrics
* Add an instrumented ScheduledExecutorService
* Fix race condition in InstrumentedThreadFactoryTest
* Correct comparison of System.nanoTime in SlidingTimeWindowReservoir
* Add SharedHealthCheckRegistries class
* Migrate benchmarks from Caliper to JMH
* New annotations: @CachedGauge, @Counted, @Metric
* Support for annotations on classes and constructors
* Allow @Metric on methods and parameters
* Add @Inherited and @Documented on all type annotations
* Adapted ehcache integration to latest ehcache version 2.8.3
* Upgrade to HttpClient 4.3
* InstrumentedHandler: Remove duplicate calls to requests.update(...)
* New metric 'utilization-max' to track thread usage out of max pool size in jetty
* Replaced Jetty-specific Request with Servlet API interfaces
* Jetty 8: Avoid NPE if InstrumentedQueuedThreadPool gauges are read too early
* Jetty 8: Call updateResponses onComplete of ContinuationListener
* Allow specifying a custom prefix Jetty 9 InstrumentedHandler
* MetricsModule is serializing wrong minute rates for timers
* MeterSerializer.serialize had m1_rate and m15_rate transposed
* Add CachedThreadStatesGaugeSet
* Monitor count of deadlock threads
* Prevent exceptions from ThreadDumpServlet on Google AppEngine
* Upgrade to logback 1.1.1
* Allow InstrumentedAppender use in logback.xml
* Use getClass() in place of AbstractInstrumentedFilter.class in generated metric names
* Update MetricsServlet with support for JSONP as alternative to CORS
* Specify the base name of the metrics as a filter init-param for the metrics captured in the AbstractInstrumentedFilter
* Add option to provide MetricFilter to MetricsServlet
* AdminServlet generates link to pretty printed healthchecks
* MetricsServlet.ContextListener doesn't initialize the context correctly
* Every reporter implements Reporter interface to indicate that is a Reporter
* Added support for passing a ScheduledExecutorService to ScheduledReporters
* Improve the ScheduledReporter#stop method
* Ensure ScheduledReporters get unique thread pools.
* Suppress runtime exceptions thrown from ScheduledReporter#report
* Ability to inject a factory of ObjectName
* Lazy fetch of PlatformMBeanServer
* JMX Reporter throws exception when metric name contains an asterisk
* onTimerRemoved in JmxListener calls registered.add
* Support for mBean servers that rewrite the supplied ObjectName upon registration
* Graphite reporter does not notify when Graphite/Carbon server is unreachable
* Persistent connections to Graphite
* Graphite constructor accepts host/port
* Graphtie Pickle sender
* Graphite UDP sender
* Graphite AMQP sender
* Add a threshold/minimum value to report before converting results to 0
* Report to multiple gmetric instances
* Escape slahes on ganglia metric names
* Upgrade slf4j to 1.7.6
* Enhancement for logging level option on Slf4jReporter


.. _rel-3.0.1:

v3.0.1: Jul 23 2013
===================

* Fixed NPE in ``MetricRegistry#name``.
* ``ScheduledReporter`` and ``JmxReporter`` now implement ``Closeable``.
* Fixed cast exception for async requests in ``metrics-jetty9``.
* Added support for ``Access-Control-Allow-Origin`` to ``MetricsServlet``.
* Fixed numerical issue with ``Meter`` EWMA rates.
* Deprecated ``AdminServletContextListener`` in favor of ``MetricsServlet.ContextListener`` and
  ``HealthCheckServlet.ContextListener``.
* Added additional constructors to ``HealthCheckServlet`` and ``MetricsServlet``.

.. _rel-3.0.0:

v3.0.0: June 10 2013
====================

* Renamed ``DefaultWebappMetricsFilter`` to ``InstrumentedFilter``.
* Renamed ``MetricsContextListener`` to ``InstrumentedFilterContextListener`` and made it fully
  abstract to avoid confusion.
* Renamed ``MetricsServletContextListener`` to ``AdminServletContextListener`` and made it fully
  abstract to avoid confusion.
* Upgraded to Servlet API 3.1.
* Upgraded to Jackson 2.2.2.
* Upgraded to Jetty 8.1.11.

.. _rel-3.0.0-RC1:

v3.0.0-RC1: May 31 2013
=======================

* Added ``SharedMetricRegistries``, a singleton for sharing named metric registries.
* Fixed XML configuration for ``metrics-ehcache``.
* Fixed XML configuration for ``metrics-jersey``.
* Fixed XML configuration for ``metrics-log4j``.
* Fixed XML configuration for ``metrics-logback``.
* Fixed a counting bug in ``metrics-jetty9``'s InstrumentedHandler.
* Added ``MetricsContextListener`` to ``metrics-servlet``.
* Added ``MetricsServletContextListener`` to ``metrics-servlets``.
* Extracted the ``Counting`` interface.
* Reverted ``SlidingWindowReservoir`` to a synchronized implementation.
* Added the implementation version to the JAR manifests.
* Made dependencies for all modules conform to Maven Enforcer's convergence rules.
* Fixed ``Slf4jReporter``'s logging of 99th percentiles.
* Added optional name prefixing to ``GraphiteReporter``.
* Added metric-specific overrides of rate and duration units to ``JmxReporter``.
* Documentation fixes.

.. _rel-3.0.0-BETA3:

v3.0.0-BETA3: May 13 2013
=========================

* Added ``ScheduledReporter#report()`` for manual reporting.
* Fixed overly-grabby catches in ``HealthCheck`` and
  ``InstrumentedResourceMethodDispatchProvider``.
* Fixed phantom reads in ``SlidingWindowReservoir``.
* Revamped ``metrics-jetty9``, removing ``InstrumentedConnector`` and improving
  the API.
* Fixed OSGi imports for ``sun.misc``.
* Added a strategy class for ``HttpClient`` metrics.
* Upgraded to Jetty 9.0.3.
* Upgraded to Jackson 2.2.1.
* Upgraded to Ehcache 2.6.6.
* Upgraded to Logback 1.0.13.
* Upgraded to HttpClient 4.2.5.
* Upgraded to gmetric4j 1.0.3, which allows for host spoofing.

.. _rel-3.0.0-BETA2:

v3.0.0-BETA2: Apr 22 2013
=========================

* Metrics is now under the ``com.codahale.metrics`` package, with the corresponding changes in Maven
  artifact groups. This should allow for an easier upgrade path without classpath conflicts.
* ``MetricRegistry`` no longer has a name.
* Added ``metrics-jetty9`` for Jetty 9.
* ``JmxReporter`` takes an optional domain property to disambiguate multiple reporters.
* Fixed Java 6 compatibility problem. (Also added Java 6 as a CI environment.)
* Added ``MetricRegistryListener.Base``.
* Switched ``Counter``, ``Meter``, and ``EWMA`` to use JSR133's ``LongAdder`` instead of
  ``AtomicLong``, improving contended concurrency.
* Added ``MetricRegistry#buildMap()``, allowing for custom map implementations in
  ``MetricRegistry``.
* Added ``MetricRegistry#removeMatching(MetricFilter)``.
* Changed ``metrics-json`` to optionally depend on ``metrics-healthcheck``.
* Upgraded to Jetty 8.1.10 for ``metrics-jetty8``.

.. _rel-3.0.0-BETA1:

v3.0.0-BETA1: Apr 01 2013
=========================

* Total overhaul of most of the core Metrics classes:

  * Metric names are now just dotted paths like ``com.example.Thing``, allowing for very flexible
    scopes, etc.
  * Meters and timers no longer have rate or duration units; those are properties of reporters.
  * Reporter architecture has been radically simplified, fixing many bugs.
  * Histograms and timers can take arbitrary reservoir implementations.
  * Added sliding window reservoir implementations.
  * Added ``MetricSet`` for sets of metrics.

* Changed package names to be OSGi-compatible and added OSGi bundling.
* Extracted JVM instrumentation to ``metrics-jvm``.
* Extracted Jackson integration to ``metrics-json``.
* Removed ``metrics-guice``, ``metrics-scala``, and ``metrics-spring``.
* Renamed ``metrics-servlet`` to ``metrics-servlets``.
* Renamed ``metrics-web`` to ``metrics-servlet``.
* Renamed ``metrics-jetty`` to ``metrics-jetty8``.
* Many more small changes!

.. _rel-2.2.0:

v2.2.0: Nov 26 2012
===================

* Removed all OSGi bundling. This will be back in 3.0.
* Added ``InstrumentedSslSelectChannelConnector`` and ``InstrumentedSslSocketConnector``.
* Made all metric names JMX-safe.
* Upgraded to Ehcache 2.6.2.
* Upgraded to Apache HttpClient 4.2.2.
* Upgraded to Jersey 1.15.
* Upgraded to Log4j 1.2.17.
* Upgraded to Logback 1.0.7.
* Upgraded to Spring 3.1.3.
* Upgraded to Jetty 8.1.8.
* Upgraded to SLF4J 1.7.2.
* Replaced usage of ``Unsafe`` in ``InstrumentedResourceMethodDispatchProvider`` with type erasure
  trickery.

.. _rel-2.1.5:

v2.1.5: Nov 19 2012
===================

* Upgraded to Jackson 2.1.1.

.. _rel-2.1.4:

v2.1.4: Nov 15 2012
===================

* Added OSGi bundling manifests.

.. _rel-2.1.3:

v2.1.3: Aug 06 2012
===================

* Upgraded to Apache HttpClient 4.2.1.
* Changed ``InstrumentedClientConnManager`` to extend ``PoolingClientConnectionManager`` instead of
  the deprecated ``ThreadSafeClientConnManager``.
* Fixed a bug in ``ExponentiallyDecayingSample`` with long periods of inactivity.
* Fixed problems with re-registering metrics in JMX.
* Added support for ``DnsResolver`` instances to ``InstrumentedClientConnManager``.
* Added support for formatted health check error messages.

.. _rel-2.1.2:

v2.1.2: Apr 11 2012
===================

* Fixed double-registration in ``metrics-guice``.

.. _rel-2.1.1:

v2.1.1: Mar 13 2012
===================

* Fixed instrumentation of all usages of ``InstrumentedHttpClient``.

.. _rel-2.1.0:

v2.1.0: Mar 12 2012
===================

* Added support for Java 7's direct and mapped buffer pool stats in ``VirtualMachineMetrics`` and
  ``metrics-servlet``.
* Added support for XML configuration in ``metrics-ehcache``.
* ``metrics-spring`` now support ``@Gauge``-annotated fields.
* Opened ``GraphiteReporter`` up for extension.
* Added ``group`` and ``type`` to ``metrics-annotations``, ``metrics-guice``, ``metrics-jersey``,
  and ``metrics-spring``.
* Fixed handling of non-int gauges in ``GangliaReporter``.
* Fixed ``NullPointerException`` errors in ``metrics-spring``.
* General improvements to ``metrics-spring``, including allowing custom ``Clock`` instances.

.. _rel-2.0.3:

v2.0.3: Feb 24 2012
===================

* Change logging of ``InstanceNotFoundException`` exceptions thrown while unregistering a metric
  in ``JmxReporter`` to ``TRACE``. It being ``WARN`` resulted in huge log dumps preventing process
  shutdowns when applications had ~1K+ metrics.
* Upgraded to Spring 3.1.1 for ``metrics-spring``.
* Upgraded to JDBI 2.31.2.
* Upgraded to Jersey 1.12.
* Upgraded to Jetty 7.6.1.
* Fixed rate units for meters in ``GangliaReporter``.

.. _rel-2.0.2:

v2.0.2: Feb 09 2012
===================

* ``InstrumentationModule`` in ``metrics-guice`` now uses the default ``MetricsRegistry`` and
  ``HealthCheckRegistry``.

.. _rel-2.0.1:

v2.0.1: Feb 08 2012
===================

* Fixed a concurrency bug in ``JmxReporter``.

.. _rel-2.0.0:

v2.0.0: Feb 07 2012
===================

* Upgraded to Jackson 1.9.4.
* Upgraded to Jetty 7.6.0.
* Added escaping for garbage collector and memory pool names in ``GraphiteReporter``.
* Fixed the inability to start and stop multiple reporter instances.
* Switched to using a backported version of ``ThreadLocalRandom`` for ``UniformSample`` and
  ``ExponentiallyDecayingSample`` to reduce lock contention on random number generation.
* Removed ``Ordered`` from ``TimedAnnotationBeanPostProcessor`` in ``metrics-spring``.
* Upgraded to JDBI 2.31.1.
* Upgraded to Ehcache 2.5.1.
* Added ``#timerContext()`` to Scala ``Timer``.

.. _rel-2.0.0-RC0:

v2.0.0-RC0: Jan 19 2012
=======================

* Added FindBugs checks to the build process.
* Fixed the catching of ``Error`` instances thrown during health checks.
* Added ``enable`` static methods to ``CsvReporter`` and changed
  ``CsvReporter(File, MetricsRegistry)`` to ``CsvReporter(MetricsRegistry, File)``.
* Slimmed down ``InstrumentedEhcache``.
* Hid the internals of ``GangliaReporter``.
* Hid the internals of ``metrics-guice``.
* Changed ``metrics-httpclient`` to consistently associate metrics with the ``org.apache`` class
  being extended.
* Hid the internals of ``metrics-httpclient``.
* Rewrote ``InstrumentedAppender`` in ``metrics-log4j``. It no longer forwards events to an
  appender. Instead, you can just attach it to your root logger to instrument logging.
* Rewrote ``InstrumentedAppender`` in ``metrics-logback``. No major API changes.
* Fixed bugs with ``@ExceptionMetered``-annotated resource methods in ``metrics-jersey``.
* Fixed bugs generating ``Snapshot`` instances from concurrently modified collections.
* Fixed edge case in ``MetricsServlet``'s thread dumps where one thread could be missed.
* Added ``RatioGauge`` and ``PercentGauge``.
* Changed ``InstrumentedQueuedThreadPool``'s ``percent-idle`` gauge to be a ratio.
* Decomposed ``MetricsServlet`` into a set of focused servlets: ``HealthCheckServlet``,
  ``MetricsServlet``, ``PingServlet``, and ``ThreadDumpServlet``. The top-level servlet which
  provides the HTML menu page is now ``AdminServlet``.
* Added ``metrics-spring``.

.. _rel-2.0.0-BETA19:

v2.0.0-BETA19: Jan 07 2012
==========================

* Added absolute memory usage to ``MetricsServlet``.
* Extracted ``@Timed`` etc. to ``metrics-annotations``.
* Added ``metrics-jersey``, which provides a class allowing you to automatically instrument all
  ``@Timed``, ``@Metered``, and ``@ExceptionMetered``-annotated resource methods.
* Moved all classes in ``metrics-scala`` from ``com.yammer.metrics`` to
  ``com.yammer.metrics.scala``.
* Renamed ``CounterMetric`` to ``Counter``.
* Renamed ``GaugeMetric`` to ``Gauge``.
* Renamed ``HistogramMetric`` to ``Histogram``.
* Renamed ``MeterMetric`` to ``Meter``.
* Renamed ``TimerMetric`` to ``Timer``.
* Added ``ToggleGauge``, which returns ``1`` the first time it's called and ``0`` every time after
  that.
* Now licensed under Apache License 2.0.
* Converted ``VirtualMachineMetrics`` to a non-singleton class.
* Removed ``Utils``.
* Removed deprecated constructors from ``Meter`` and ``Timer``.
* Removed ``LoggerMemoryLeakFix``.
* ``DeathRattleExceptionHandler`` now logs to SLF4J, not syserr.
* Added ``MetricsRegistry#groupedMetrics()``.
* Removed ``Metrics#allMetrics()``.
* Removed ``Metrics#remove(MetricName)``.
* Removed ``MetricsRegistry#threadPools()`` and ``#newMeterTickThreadPool()`` and added
  ``#newScheduledThreadPool``.
* Added ``MetricsRegistry#shutdown()``.
* Renamed ``ThreadPools#shutdownThreadPools()`` to ``#shutdown()``.
* Replaced ``HealthCheck``'s abstract ``name`` method with a required constructor parameter.
* ``HealthCheck#check()`` is now ``protected``.
* Moved ``DeadlockHealthCheck`` from ``com.yammer.metrics.core`` to ``com.yammer.metrics.utils``.
* Added ``HealthCheckRegistry#unregister(HealthCheck)``.
* Fixed typo in ``VirtualMachineMetrics`` and ``MetricsServlet``: ``commited`` to ``committed``.
* Changed ``MetricsRegistry#createName`` to ``protected``.
* All metric types are created exclusively through ``MetricsRegistry`` now.
* ``Metrics.newJmxGauge`` and ``MetricsRegistry.newJmxGauge`` are deprecated.
* Fixed heap metrics in ``VirtualMachineMetrics``.
* Added ``Snapshot``, which calculates quantiles.
* Renamed ``Percentiled`` to ``Sampling`` and dropped ``percentile`` and ``percentiles`` in favor of
  producing ``Snapshot`` instances. This affects both ``Histogram`` and ``Timer``.
* Renamed ``Summarized`` to ``Summarizable``.
* Changed order of ``CsvReporter``'s construction parameters.
* Renamed ``VirtualMachineMetrics.GarbageCollector`` to
  ``VirtualMachineMetrics.GarbageCollectorStats``.
* Moved Guice/Servlet support from ``metrics-servlet`` to ``metrics-guice``.
* Removed ``metrics-aop``.
* Removed ``newJmxGauge`` from both ``Metrics`` and ``MetricsRegistry``. Just use ``JmxGauge``.
* Moved ``JmxGauge`` to ``com.yammer.metrics.util``.
* Moved ``MetricPredicate`` to ``com.yammer.metrics.core``.
* Moved ``NameThreadFactory`` into ``ThreadPools`` and made ``ThreadPools`` package-visible.
* Removed ``Timer#values()``, ``Histogram#values()``, and ``Sample#values()``. Use ``getSnapshot()``
  instead.
* Removed ``Timer#dump(File)`` and ``Histogram#dump(File)``, and ``Sample#dump(File)``. Use
  ``Snapshot#dump(File)`` instead.

.. _rel-2.0.0-BETA18:

v2.0.0-BETA18: Dec 16 2011
==========================

* Added ``DeathRattleExceptionHandler``.
* Fixed NPE in ``VirtualMachineMetrics``.
* Added decorators for connectors and thread pools in ``metrics-jetty``.
* Added ``TimerMetric#time()`` and ``TimerContext``.
* Added a shorter factory method for millisecond/second timers.
* Switched tests to JUnit.
* Improved logging in ``GangliaReporter``.
* Improved random number generation for ``UniformSample``.
* Added ``metrics-httpclient`` for instrumenting Apache HttpClient 4.1.
* Massively overhauled the reporting code.
* Added support for instrumented, non-``public`` methods in ``metrics-guice``.
* Added ``@ExceptionMetered`` to ``metrics-guice``.
* Added group prefixes to ``GangliaReporter``.
* Added ``CvsReporter``, which outputs metric values to ``.csv`` files.
* Improved metric name sanitization in ``GangliaReporter``.
* Added ``Metrics.shutdown()`` and improved metrics lifecycle behavior.
* Added ``metrics-web``.
* Upgraded to ehcache 2.5.0.
* Many, many refactorings.
* ``metrics-servlet`` now responds with ``501 Not Implememented`` when no health checks have been
  registered.
* Many internal refactorings for testability.
* Added histogram counts to ``metrics-servlet``.
* Fixed a race condition in ``ExponentiallyDecayingSample``.
* Added timezone and locale support to ``ConsoleReporter``.
* Added ``metrics-aop`` for Guiceless support of method annotations.
* Added ``metrics-jdbi`` which adds instrumentation to JDBI_.
* Fixed NPE for metrics which belong to classes in the default package.
* Now deploying artifacts to Maven Central.

.. _JDBI: http://www.jdbi.org

.. _rel-2.0.0-BETA17:

v2.0.0-BETA17: Oct 07 2011
==========================

* Added an option message to successful health check results.
* Fixed locale issues in ``GraphiteReporter``.
* Added ``GangliaReporter``.
* Added per-HTTP method timers to ``InstrumentedHandler`` in ``metrics-jetty``.
* Fixed a thread pool leak for meters.
* Added ``#dump(File)`` to ``HistogramMetric`` and ``TimerMetric``.
* Upgraded to Jackson 1.9.x.
* Upgraded to slf4j 1.6.2.
* Upgraded to logback 0.9.30.
* Upgraded to ehcache 2.4.5.
* Surfaced ``Metrics.removeMetric()``.

.. _rel-2.0.0-BETA16:

v2.0.0-BETA16: Aug 23 2011
==========================

* Fixed a bug in GC monitoring.

.. _rel-2.0.0-BETA15:

v2.0.0-BETA15: Aug 15 2011
==========================

* Fixed dependency scopes for ``metrics-jetty``.
* Added time and VM version to ``vm`` output of ``MetricsServlet``.
* Dropped ``com.sun.mangement``-based GC instrumentation in favor of a
  ``java.lang.management``-based one. ``getLastGcInfo`` has a nasty native memory leak in it, plus
  it often returned incorrect data.
* Upgraded to Jackson 1.8.5.
* Upgraded to Jetty 7.4.5.
* Added sanitization for metric names in ``GraphiteReporter``.
* Extracted out a ``Clock`` interface for timers for non-wall-clock timing.
* Extracted out most of the remaining statics into ``MetricsRegistry`` and ``HealthCheckRegistry``.
* Added an init parameter to ``MetricsServlet`` for disabling the ``jvm`` section.
* Added a Guice module for ``MetricsServlet``.
* Added dynamic metric names.
* Upgraded to ehcache 2.4.5.
* Upgraded to logback 0.9.29.
* Allowed for the removal of metrics.
* Added the ability to filter metrics exposed by a reporter to those which match a given predicate.

.. _rel-2.0.0-BETA14:

v2.0.0-BETA14: Jul 05 2011
==========================

* Moved to Maven for a build system and extracted the Scala façade to a ``metrics-scala`` module
  which is now the only cross-built module. All other modules dropped the Scala version suffix in
  their ``artifactId``.
* Fixed non-heap metric name in ``GraphiteReporter``.
* Fixed stability error in ``GraphiteReporter`` when dealing with unavailable servers.
* Fixed error with anonymous, instrumented classes.
* Fixed error in ``MetricsServlet`` when a gauge throws an exception.
* Fixed error with bogus GC run times.
* Link to the pretty JSON output from the ``MetricsServlet`` menu page.
* Fixed potential race condition in histograms' variance calculations.
* Fixed memory pool reporting for the G1 collector.

.. _rel-2.0.0-BETA13:

v2.0.0-BETA13: May 13 2011
==========================

* Fixed a bug in the initial startup phase of the ``JmxReporter``.
* Added ``metrics-ehcache``, for the instrumentation of ``Ehcache`` instances.
* Fixed a typo in ``metrics-jetty``'s ``InstrumentedHandler``.
* Added name prefixes to ``GraphiteReporter``.
* Added JVM metrics reporting to ``GraphiteReporter``.
* Actually fixed ``MetricsServlet``'s links when the servlet has a non-root context path.
* Now cross-building for Scala 2.9.0.
* Added ``pretty`` query parameter for ``MetricsServlet`` to format the JSON object for human
  consumption.
* Added ``no-cache`` headers to the ``MetricsServlet`` responses.

.. _rel-2.0.0-BETA12:

v2.0.0-BETA12: May 09 2011
==========================

* Upgraded to Jackson 1.7.6.
* Added a new instrumented Log4J appender.
* Added a new instrumented Logback appender. Thanks to Bruce Mitchener
  (@waywardmonkeys) for the patch.
* Added a new reporter for the Graphite_ aggregation system. Thanks to Mahesh Tiyyagura (@tmahesh)
  for the patch.
* Added scoped metric names.
* Added Scala 2.9.0.RC{2,3,4} as build targets.
* Added meters to Jetty handler for the percent of responses which have ``4xx`` or ``5xx`` status
  codes.
* Changed the Servlet API to be a ``provided`` dependency. Thanks to Mårten Gustafson (@chids) for
  the patch.
* Separated project into modules:

  * ``metrics-core``: A dependency-less project with all the core metrics.
  * ``metrics-graphite``: A reporter for the [Graphite](http://graphite.wikidot.com)
    aggregation system.
  * ``metrics-guice``: Guice AOP support.
  * ``metrics-jetty``: An instrumented Jetty handler.
  * ``metrics-log4j``: An instrumented Log4J appender.
  * ``metrics-logback``: An instrumented Logback appender.
  * ``metrics-servlet``: The Metrics servlet with context listener.

.. _Graphite: http://graphite.wikidot.com

.. _rel-2.0.0-BETA11:

v2.0.0-BETA11: Apr 27 2011
==========================

* Added thread state and deadlock detection metrics.
* Fix ``VirtualMachineMetrics``' initialization.
* Context path fixes for the servlet.
* Added the ``@Gauge`` annotation.
* Big reworking of the exponentially-weighted moving average code for meters. Thanks to JD Maturen
  (@sku) and John Ewart (@johnewart) for pointing this out.
* Upgraded to Guice 3.0.
* Upgraded to Jackson 1.7.5.
* Upgraded to Jetty 7.4.0.
* Big rewrite of the servlet's thread dump code.
* Fixed race condition in ``ExponentiallyDecayingSample``. Thanks to Martin Traverso (@martint) for
  the patch.
* Lots of spelling fixes in Javadocs. Thanks to Bruce Mitchener (@waywardmonkeys) for the patch.
* Added Scala 2.9.0.RC1 as a build target. Thanks to Bruce Mitchener (@waywardmonkeys) for the
  patch.
* Patched a hilarious memory leak in ``java.util.logging``.

.. _rel-2.0.0-BETA10:

v2.0.0-BETA10: Mar 25 2011
==========================

* Added Guice AOP annotations: ``@Timed`` and ``@Metered``.
* Added ``HealthCheck#name()``.
* Added ``Metrics.newJmxGauge()``.
* Moved health checks into ``HealthChecks``.
* Upgraded to Jackson 1.7.3 and Jetty 7.3.1.

.. _rel-2.0.0-BETA9:

v2.0.0-BETA9: Mar 14 2011
=========================

* Fixed ``JmxReporter`` lag.
* Added default arguments to timers and meters.
* Added default landing page to the servlet.
* Improved the performance of ``ExponentiallyDecayingSample``.
* Fixed an integer overflow bug in ``UniformSample``.
* Added linear scaling to ``ExponentiallyDecayingSample``.

.. _rel-2.0.0-BETA8:

v2.0.0-BETA8: Mar 01 2011
=========================

* Added histograms.
* Added biased sampling for timers.
* Added dumping of timer/histogram samples via the servlet.
* Added dependency on ``jackon-mapper``.
* Added classname filtering for the servlet.
* Added URI configuration for the servlet.

.. _rel-2.0.0-BETA7:

v2.0.0-BETA7: Jan 12 2011
=========================

* Added ``JettyHandler``.
* Made the ``Servlet`` dependency optional.

.. _rel-2.0.0-BETA6:

v2.0.0-BETA6: Jan 12 2011
=========================

* Fix ``JmxReporter`` initialization.

.. _rel-2.0.0-BETA5:

v2.0.0-BETA5: Jan 11 2011
=========================

* Dropped ``Counter#++`` and ``Counter#--``.
* Added ``Timer#update``.
* Upgraded to Jackson 1.7.0.
* Made JMX reporting implicit.
* Added health checks.

.. _rel-2.0.0-BETA3:

v2.0.0-BETA3: Dec 23 2010
=========================

* Fixed thread names and some docs.

.. _rel-2.0.0-BETA2:

v2.0.0-BETA2: Dec 22 2010
=========================

* Fixed a memory leak in ``MeterMetric``.

.. _rel-2.0.0-BETA1:

v2.0.0-BETA1: Dec 22 2010
=========================

* Total rewrite in Java.

.. _rel-1.0.7:

v1.0.7: Sep 21 2010
===================

* Added ``median`` to ``Timer``.
* Added ``p95`` to ``Timer`` (95th percentile).
* Added ``p98`` to ``Timer`` (98th percentile).
* Added ``p99`` to ``Timer`` (99th percentile).

.. _rel-1.0.6:

v1.0.6: Jul 15 2010
===================

* Now compiled exclusively for 2.8.0 final.

.. _rel-1.0.5:

v1.0.5: Jun 01 2010
===================

* Documentation fix.
* Added ``TimedToggle``, which may or may not be useful at all.
* Now cross-building for RC2 and RC3.

.. _rel-1.0.4:

v1.0.4: Apr 27 2010
===================

* Blank ``Timer`` instances (i.e., those which have recorded no timings yet) no longer explode when
  asked for metrics for that which does not yet exist.
* Nested classes, companion objects, and singletons don't have trailing ``$`` characters messing up
  JMX's good looks.

.. _rel-1.0.3:

v1.0.3: Apr 16 2010
===================

* Fixed some issues with the `implicit.ly`__ plumbing.
* Tweaked the sample size for ``Timer``, giving it 99.9% confidence level with a %5 margin of error
  (for a normally distributed variable, which it almost certainly isn't.)
* ``Sample#iterator`` returns only the recorded data, not a bunch of zeros.
* Moved units of ``Timer``, ``Meter``, and ``LoadMeter`` to their own attributes, which allows for
  easy export of Metrics data via JMX to things like Ganglia__ or whatever.
  
.. __: http://implicit.ly
.. __: http://ganglia.sourceforge.net/

.. _rel-1.0.2:

v1.0.2: Mar 08 2010
===================

* ``Timer`` now uses Welford's algorithm for calculating running variance, which means no more
  hilariously wrong standard deviations (e.g., ``NaN``).
* ``Timer`` now supports ``+=(Long)`` for pre-recorded, nanosecond-precision timings.

.. _rel-1.0.1:

v1.0.1: Mar 05 2010
===================

* changed ``Sample`` to use an ``AtomicReferenceArray``

.. _rel-1.0.0:

v1.0.0: Feb 27 2010
===================

* Initial release

---

## File: docs/source/manual/caffeine.rst

.. _manual-caffeine:

#####################
Instrumenting Caffeine
#####################

.. highlight:: text

.. rubric:: The ``metrics-caffeine`` module provides ``MetricsStatsCounter``, a metrics listener for
            Caffeine_ caches:

.. _Caffeine: https://github.com/ben-manes/caffeine

.. code-block:: java

    LoadingCache cache = Caffeine.newBuilder()
        .recordStats(() -> new MetricsStatsCounter(registry, "cache"))
        .build(key -> key);

The listener publishes these metrics:

+---------------------------+----------------------------------------------------------------------+
| ``hits``                  | Number of times a requested item was found in the cache.             |
+---------------------------+----------------------------------------------------------------------+
| ``misses``                | Number of times a requested item was not found in the cache.         |
+---------------------------+----------------------------------------------------------------------+
| ``loads-success``         | Timer for successful loads into cache.                               |
+---------------------------+----------------------------------------------------------------------+
| ``loads-failure``         | Timer for failed loads into cache.                                   |
+---------------------------+----------------------------------------------------------------------+
| ``evictions``             | Histogram of eviction weights      .                                 |
+---------------------------+----------------------------------------------------------------------+
| ``evictions-weight``      | Total weight of evicted entries.                                     |
+---------------------------+----------------------------------------------------------------------+
| ``evictions.<CAUSE>``     | Histogram of eviction weights for each RemovalCause                  |
+---------------------------+----------------------------------------------------------------------+

---

## File: docs/source/manual/collectd.rst

.. _manual-collectd:

#####################
Reporting to Collectd
#####################

The ``metrics-collectd`` module provides ``CollectdReporter``, which allows your application to
constantly stream metric values to a Collectd_ server:

.. _Collectd: https://collectd.org/

.. code-block:: java

    final Sender sender = new Sender("collectd.example.com", 2007);
    final CollectdReporter reporter = CollectdReporter.forRegistry(registry)
                                                      .convertRatesTo(TimeUnit.SECONDS)
                                                      .convertDurationsTo(TimeUnit.MILLISECONDS)
                                                      .filter(MetricFilter.ALL)
                                                      .build(sender);
    reporter.start(1, TimeUnit.MINUTES);

---

## File: docs/source/manual/core.rst

.. _manual-core:

############
Metrics Core
############

.. highlight:: text

The central library for Metrics is ``metrics-core``, which provides some basic functionality:

* Metric :ref:`registries <man-core-registries>`.
* The five metric types: :ref:`man-core-gauges`, :ref:`man-core-counters`,
  :ref:`man-core-histograms`, :ref:`man-core-meters`, and :ref:`man-core-timers`.
* Reporting metrics values via :ref:`JMX <man-core-reporters-jmx>`, the
  :ref:`console <man-core-reporters-console>`, :ref:`CSV <man-core-reporters-csv>` files, and
  :ref:`SLF4J loggers <man-core-reporters-slf4j>`.

.. _man-core-registries:

Metric Registries
=================

The starting point for Metrics is the ``MetricRegistry`` class, which is a collection of all the
metrics for your application (or a subset of your application).

Generally you only need one ``MetricRegistry`` instance per application, although you may choose
to use more if you want to organize your metrics in particular reporting groups.

Global named registries can also be shared through the static ``SharedMetricRegistries`` class. This
allows the same registry to be used in different sections of code without explicitly passing a ``MetricRegistry``
instance around.

Like all Metrics classes, ``SharedMetricRegistries`` is fully thread-safe.

.. _man-core-names:

Metric Names
============

Each metric is associated with a ``MetricRegistry``, and has a unique *name* within that registry. This is a simple
dotted name, like ``com.example.Queue.size``. This flexibility allows you to encode a wide variety of
context directly into a metric's name. If you have two instances of ``com.example.Queue``, you can give
them more specific: ``com.example.Queue.requests.size`` vs. ``com.example.Queue.responses.size``, for example.

``MetricRegistry`` has a set of static helper methods for easily creating names:

.. code-block:: java

    MetricRegistry.name(Queue.class, "requests", "size")
    MetricRegistry.name(Queue.class, "responses", "size")

These methods will also elide any ``null`` values, allowing for easy optional scopes.

.. _man-core-gauges:

Gauges
======

A gauge is the simplest metric type. It just returns a *value*. If, for example, your application
has a value which is maintained by a third-party library, you can easily expose it by registering a
``Gauge`` instance which returns that value:

.. code-block:: java

    registry.register(name(SessionStore.class, "cache-evictions"), new Gauge() {
        @Override
        public Integer getValue() {
            return cache.getEvictionsCount();
        }
    });

This will create a new gauge named ``com.example.proj.auth.SessionStore.cache-evictions`` which will
return the number of evictions from the cache.

.. _man-core-gauges-jmx:

JMX Gauges
----------

Given that many third-party libraries often expose metrics only via JMX, Metrics provides the
``JmxAttributeGauge`` class, which takes the object name of a JMX MBean and the name of an attribute
and produces a gauge implementation which returns the value of that attribute:

.. code-block:: java

    registry.register(name(SessionStore.class, "cache-evictions"),
                     new JmxAttributeGauge("net.sf.ehcache:type=Cache,scope=sessions,name=eviction-count", "Value"));

.. _man-core-gauges-ratio:

Ratio Gauges
------------

A ratio gauge is a simple way to create a gauge which is the ratio between two numbers:

.. code-block:: java

    public class CacheHitRatio extends RatioGauge {
        private final Meter hits;
        private final Timer calls;

        public CacheHitRatio(Meter hits, Timer calls) {
            this.hits = hits;
            this.calls = calls;
        }

        @Override
        public Ratio getRatio() {
            return Ratio.of(hits.getOneMinuteRate(),
                            calls.getOneMinuteRate());
        }
    }

This gauge returns the ratio of cache hits to misses using a meter and a timer.

.. _man-core-gauges-cached:

Cached Gauges
-------------

A cached gauge allows for a more efficient reporting of values which are expensive
to calculate. The value is cached for the period specified in the constructor. The "getValue()"
method called by the client only returns the cached value. The protected "loadValue()" method
is only called internally to reload the cache value.

.. code-block:: java

    registry.register(name(Cache.class, cache.getName(), "size"),
                      new CachedGauge<Long>(10, TimeUnit.MINUTES) {
                          @Override
                          protected Long loadValue() {
                              // assume this does something which takes a long time
                              return cache.getSize();
                          }
                      });

.. _man-core-gauges-derivative:

Derivative Gauges
-----------------

A derivative gauge allows you to derive values from other gauges' values:

.. code-block:: java

    public class CacheSizeGauge extends DerivativeGauge<CacheStats, Long> {
        public CacheSizeGauge(Gauge<CacheStats> statsGauge) {
            super(statsGauge);
        }

        @Override
        protected Long transform(CacheStats stats) {
            return stats.getSize();
        }
    }

.. _man-core-counters:

Counters
========

A counter is a simple incrementing and decrementing 64-bit integer:

.. code-block:: java

    final Counter evictions = registry.counter(name(SessionStore.class, "cache-evictions"));
    evictions.inc();
    evictions.inc(3);
    evictions.dec();
    evictions.dec(2);

All ``Counter`` metrics start out at 0.

.. _man-core-histograms:

Histograms
==========

A ``Histogram`` measures the distribution of values in a stream of data: e.g., the number of results
returned by a search:

.. code-block:: java

    final Histogram resultCounts = registry.histogram(name(ProductDAO.class, "result-counts"));
    resultCounts.update(results.size());

``Histogram`` metrics allow you to measure not just easy things like the min, mean, max, and
standard deviation of values, but also quantiles__ like the median or 95th percentile.

.. __: http://en.wikipedia.org/wiki/Quantile

Traditionally, the way the median (or any other quantile) is calculated is to take the entire data
set, sort it, and take the value in the middle (or 1% from the end, for the 99th percentile). This
works for small data sets, or batch processing systems, but not for high-throughput, low-latency
services.

The solution for this is to sample the data as it goes through. By maintaining a small, manageable
reservoir which is statistically representative of the data stream as a whole, we can quickly and
easily calculate quantiles which are valid approximations of the actual quantiles. This technique is
called **reservoir sampling**.

Metrics provides a number of different ``Reservoir`` implementations, each of which is useful.

.. _man-core-histograms-uniform:

Uniform Reservoirs
------------------

A histogram with a uniform reservoir produces quantiles which are valid for the entirety of the
histogram's lifetime. It will return a median value, for example, which is the median of all the
values the histogram has ever been updated with. It does this by using an algorithm called
`Vitter's R`__), which randomly selects values for the reservoir with linearly-decreasing
probability.

.. __: http://www.cs.umd.edu/~samir/498/vitter.pdf

Use a uniform histogram when you're interested in long-term measurements. Don't use one where you'd
want to know if the distribution of the underlying data stream has changed recently.

.. _man-core-histograms-exponential:

Exponentially Decaying Reservoirs
---------------------------------

A histogram with an exponentially decaying reservoir produces quantiles which are representative of
(roughly) the last five minutes of data. It does so by using a
`forward-decaying priority reservoir`__ with an exponential weighting towards newer data. Unlike the
uniform reservoir, an exponentially decaying reservoir represents **recent data**, allowing you to
know very quickly if the distribution of the data has changed. :ref:`man-core-timers` use histograms
with exponentially decaying reservoirs by default.

.. __: http://dimacs.rutgers.edu/~graham/pubs/papers/fwddecay.pdf

.. _man-core-histograms-sliding:

Sliding Window Reservoirs
-------------------------

A histogram with a sliding window reservoir produces quantiles which are representative of the past
``N`` measurements.

.. _man-core-histograms-sliding-time:

Sliding Time Window Reservoirs
------------------------------

A histogram with a sliding time window reservoir produces quantiles which are strictly
representative of the past ``N`` seconds (or other time period).

.. warning::

    While ``SlidingTimeWindowReservoir`` is easier to understand than
    ``ExponentiallyDecayingReservoir``, it is not bounded in size, so using it to sample a
    high-frequency process can require a significant amount of memory. Because it records every
    measurement, it's also the slowest reservoir type.

.. hint::

    Try to use our new optimised version of ``SlidingTimeWindowReservoir`` called ``SlidingTimeWindowArrayReservoir``.
    It brings much lower memory overhead. Also it's allocation/free patterns are different,
    so GC overhead is 60x-80x lower then ``SlidingTimeWindowReservoir``. Now ``SlidingTimeWindowArrayReservoir`` is
    comparable with ``ExponentiallyDecayingReservoir`` in terms GC overhead and performance.
    As for required memory, ``SlidingTimeWindowArrayReservoir`` takes ~128 bits per stored measurement and you can simply
    calculate required amount of heap.

    Example: 10K measurements / sec with reservoir storing time of 1 minute will take
    10000 * 60 * 128 / 8 = 9600000 bytes ~ 9 megabytes

.. _man-core-meters:

Meters
======

A meter measures the *rate* at which a set of events occur:

.. code-block:: java

    final Meter getRequests = registry.meter(name(WebProxy.class, "get-requests", "requests"));
    getRequests.mark();
    getRequests.mark(requests.size());

Meters measure the rate of the events in a few different ways. The *mean* rate is the average rate
of events. It's generally useful for trivia, but as it represents the total rate for your
application's entire lifetime (e.g., the total number of requests handled, divided by the number of
seconds the process has been running), it doesn't offer a sense of recency. Luckily, meters also
record three different *exponentially-weighted moving average* rates: the 1-, 5-, and 15-minute
moving averages.

.. hint::

    Just like the Unix load averages visible in ``uptime`` or ``top``.

.. _man-core-timers:

Timers
======

A timer is basically a :ref:`histogram <man-core-histograms>` of the duration of a type of event and
a :ref:`meter <man-core-meters>` of the rate of its occurrence.

.. code-block:: java

    final Timer timer = registry.timer(name(WebProxy.class, "get-requests"));

    final Timer.Context context = timer.time();
    try {
        // handle request
    } finally {
        context.stop();
    }

.. note::

    Elapsed times for it events are measured internally in nanoseconds, using Java's high-precision
    ``System.nanoTime()`` method. Its precision and accuracy vary depending on operating system and
    hardware.

.. _man-core-sets:

Metric Sets
===========

Metrics can also be grouped together into reusable metric sets using the ``MetricSet`` interface.
This allows library authors to provide a single entry point for the instrumentation of a wide
variety of functionality.

.. _man-core-reporters:

Reporters
=========

Reporters are the way that your application exports all the measurements being made by its metrics.
``metrics-core`` comes with four ways of exporting your metrics:
:ref:`JMX <man-core-reporters-jmx>`, :ref:`console <man-core-reporters-console>`,
:ref:`SLF4J <man-core-reporters-slf4j>`, and :ref:`CSV <man-core-reporters-csv>`.

.. _man-core-reporters-jmx:

JMX
---

With ``JmxReporter``, you can expose your metrics as JMX MBeans. To explore this you can use
VisualVM__ (which ships with most JDKs as ``jvisualvm``) with the VisualVM-MBeans plugins installed
or JConsole (which ships with most JDKs as ``jconsole``):

.. __: http://visualvm.java.net/

.. image:: ../metrics-visualvm.png
    :alt: Metrics exposed as JMX MBeans being viewed in VisualVM's MBeans browser

.. tip::

    If you double-click any of the metric properties, VisualVM will start graphing the data for that
    property. Sweet, eh?

.. warning::

    We don't recommend that you try to gather metrics from your production environment. JMX's RPC
    API is fragile and bonkers. For development purposes and browsing, though, it can be very
    useful.

To report metrics via JMX:

.. code-block:: java

    final JmxReporter reporter = JmxReporter.forRegistry(registry).build();
    reporter.start();

.. _man-core-reporters-console:

Console
-------

For simple benchmarks, Metrics comes with ``ConsoleReporter``, which periodically reports all
registered metrics to the console:

.. code-block:: java

    final ConsoleReporter reporter = ConsoleReporter.forRegistry(registry)
                                                    .convertRatesTo(TimeUnit.SECONDS)
                                                    .convertDurationsTo(TimeUnit.MILLISECONDS)
                                                    .build();
    reporter.start(1, TimeUnit.MINUTES);

.. _man-core-reporters-csv:

CSV
---

For more complex benchmarks, Metrics comes with ``CsvReporter``, which periodically appends to a set
of ``.csv`` files in a given directory:

.. code-block:: java

    final CsvReporter reporter = CsvReporter.forRegistry(registry)
                                            .formatFor(Locale.US)
                                            .convertRatesTo(TimeUnit.SECONDS)
                                            .convertDurationsTo(TimeUnit.MILLISECONDS)
                                            .build(new File("~/projects/data/"));
    reporter.start(1, TimeUnit.SECONDS);

For each metric registered, a ``.csv`` file will be created, and every second its state will be
written to it as a new row.

.. _man-core-reporters-slf4j:

SLF4J
-----

It's also possible to log metrics to an SLF4J logger:

.. code-block:: java

    final Slf4jReporter reporter = Slf4jReporter.forRegistry(registry)
                                                .outputTo(LoggerFactory.getLogger("com.example.metrics"))
                                                .convertRatesTo(TimeUnit.SECONDS)
                                                .convertDurationsTo(TimeUnit.MILLISECONDS)
                                                .build();
    reporter.start(1, TimeUnit.MINUTES);

.. _man-core-reporters-other:

Other Reporters
---------------

Metrics has other reporter implementations, too:

* :ref:`MetricsServlet <manual-servlets>` is a servlet which not only exposes your metrics as a JSON
  object, but it also runs your health checks, performs thread dumps, and exposes valuable JVM-level
  and OS-level information.
* :ref:`GraphiteReporter <manual-graphite>` allows you to constantly stream metrics data to your
  Graphite servers.

---

## File: docs/source/manual/ehcache.rst

.. _manual-ehcache:

#####################
Instrumenting Ehcache
#####################

.. highlight:: text

.. rubric:: The ``metrics-ehcache`` module provides ``InstrumentedEhcache``, a decorator for
            Ehcache_ caches:

.. _Ehcache: http://ehcache.org/documentation

.. code-block:: java

    final Cache c = new Cache(new CacheConfiguration("test", 100));
    MANAGER.addCache(c);
    this.cache = InstrumentedEhcache.instrument(registry, c);

Instrumenting an ``Ehcache`` instance creates gauges for all of the Ehcache-provided statistics:

+---------------------------+----------------------------------------------------------------------+
| ``hits``                  | The number of times a requested item was found in the cache.         |
+---------------------------+----------------------------------------------------------------------+
| ``in-memory-hits``        | Number of times a requested item was found in the memory store.      |
+---------------------------+----------------------------------------------------------------------+
| ``off-heap-hits``         | Number of times a requested item was found in the off-heap store.    |
+---------------------------+----------------------------------------------------------------------+
| ``on-disk-hits``          | Number of times a requested item was found in the disk store.        |
+---------------------------+----------------------------------------------------------------------+
| ``misses``                | Number of times a requested item was not found in the cache.         |
+---------------------------+----------------------------------------------------------------------+
| ``in-memory-misses``      | Number of times a requested item was not found in the memory store.  |
+---------------------------+----------------------------------------------------------------------+
| ``off-heap-misses``       | Number of times a requested item was not found in the off-heap store.|
+---------------------------+----------------------------------------------------------------------+
| ``on-disk-misses``        | Number of times a requested item was not found in the disk store.    |
+---------------------------+----------------------------------------------------------------------+
| ``objects``               | Number of elements stored in the cache.                              |
+---------------------------+----------------------------------------------------------------------+
| ``in-memory-objects``     | Number of objects in the memory store.                               |
+---------------------------+----------------------------------------------------------------------+
| ``off-heap-objects``      | Number of objects in the off-heap store.                             |
+---------------------------+----------------------------------------------------------------------+
| ``on-disk-objects``       | Number of objects in the disk store.                                 |
+---------------------------+----------------------------------------------------------------------+
| ``mean-get-time``         | The average get time. Because ehcache supports JDK1.4.2, each get    |
|                           | time uses ``System.currentTimeMillis()``, rather than nanoseconds.   |
|                           | The accuracy is thus limited.                                        |
+---------------------------+----------------------------------------------------------------------+
| ``mean-search-time``      | The average execution time (in milliseconds) within the last sample  |
|                           | period.                                                              |
+---------------------------+----------------------------------------------------------------------+
| ``eviction-count``        | The number of cache evictions, since the cache was created, or       |
|                           | statistics were cleared.                                             |
+---------------------------+----------------------------------------------------------------------+
| ``searches-per-second``   | The number of search executions that have completed in the last      |
|                           | second.                                                              |
+---------------------------+----------------------------------------------------------------------+
| ``accuracy``              | A human readable description of the accuracy setting. One of "None", |
|                           | "Best Effort" or "Guaranteed".                                       |
+---------------------------+----------------------------------------------------------------------+

It also adds full timers for the cache's ``get`` and ``put`` methods.

The metrics are all scoped to the cache's class and name, so a ``Cache`` instance named ``users``
would have metric names like ``net.sf.ehcache.Cache.users.get``, etc.

---

## File: docs/source/manual/graphite.rst

.. _manual-graphite:

#####################
Reporting to Graphite
#####################

The ``metrics-graphite`` module provides ``GraphiteReporter``, which allows your application to
constantly stream metric values to a Graphite_ server:

.. _Graphite: http://graphite.wikidot.com/

.. code-block:: java

    final Graphite graphite = new Graphite(new InetSocketAddress("graphite.example.com", 2003));
    final GraphiteReporter reporter = GraphiteReporter.forRegistry(registry)
                                                      .prefixedWith("web1.example.com")
                                                      .convertRatesTo(TimeUnit.SECONDS)
                                                      .convertDurationsTo(TimeUnit.MILLISECONDS)
                                                      .filter(MetricFilter.ALL)
                                                      .build(graphite);
    reporter.start(1, TimeUnit.MINUTES);

If you prefer to write metrics in batches using pickle, you can use the ``PickledGraphite``:

.. code-block:: java

    final PickledGraphite pickledGraphite = new PickledGraphite(new InetSocketAddress("graphite.example.com", 2004));
    final GraphiteReporter reporter = GraphiteReporter.forRegistry(registry)
                                                      .prefixedWith("web1.example.com")
                                                      .convertRatesTo(TimeUnit.SECONDS)
                                                      .convertDurationsTo(TimeUnit.MILLISECONDS)
                                                      .filter(MetricFilter.ALL)
                                                      .build(pickledGraphite);
    reporter.start(1, TimeUnit.MINUTES);

---

## File: docs/source/manual/healthchecks.rst

.. _man-healthchecks:

#############
Health Checks
#############

Metrics also provides you with a consistent, unified way of performing application health checks. A
health check is basically a small self-test which your application performs to verify that a
specific component or responsibility is performing correctly.

To create a health check, extend the ``HealthCheck`` class:

.. code-block:: java

    public class DatabaseHealthCheck extends HealthCheck {
        private final Database database;

        public DatabaseHealthCheck(Database database) {
            this.database = database;
        }

        @Override
        protected Result check() throws Exception {
            if (database.ping()) {
                return Result.healthy();
            }
            return Result.unhealthy("Can't ping database");
        }
    }

In this example, we've created a health check for a ``Database`` class on which our application
depends. Our fictitious ``Database`` class has a ``#ping()`` method, which executes a safe test
query (e.g., ``SELECT 1``). ``#ping()`` returns ``true`` if the query returns the expected result,
returns ``false`` if it returns something else, and throws an exception if things have gone
seriously wrong.

Our ``DatabaseHealthCheck``, then, takes a ``Database`` instance and in its ``#check()`` method,
attempts to ping the database. If it can, it returns a **healthy** result. If it can't, it returns
an **unhealthy** result.

.. note::

    Exceptions thrown inside a health check's ``#check()`` method are automatically caught and
    turned into unhealthy results with the full stack trace.

To register a health check, either use a ``HealthCheckRegistry`` instance:

.. code-block:: java

    registry.register("database", new DatabaseHealthCheck(database));

You can also run the set of registered health checks:

.. code-block:: java

    for (Entry<String, Result> entry : registry.runHealthChecks().entrySet()) {
        if (entry.getValue().isHealthy()) {
            System.out.println(entry.getKey() + ": OK");
        } else {
            System.out.println(entry.getKey() + ": FAIL");
        }
    }