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Posted to commits@sling.apache.org by jo...@apache.org on 2022/08/11 10:20:57 UTC
[sling-site] 01/01: update Sling Commons Metrics with latest changes
This is an automated email from the ASF dual-hosted git repository.
joerghoh pushed a commit to branch commons-metrics-update
in repository https://gitbox.apache.org/repos/asf/sling-site.git
commit 696219ee61b10291aa7c24f4fc864a97e866f7f1
Author: Joerg Hoh <jo...@apache.org>
AuthorDate: Thu Aug 11 12:20:42 2022 +0200
update Sling Commons Metrics with latest changes
---
.../jbake/content/documentation/bundles/metrics.md | 69 +++++++++++++++-------
1 file changed, 48 insertions(+), 21 deletions(-)
diff --git a/src/main/jbake/content/documentation/bundles/metrics.md b/src/main/jbake/content/documentation/bundles/metrics.md
index 22c5a95a5..c6205c20c 100644
--- a/src/main/jbake/content/documentation/bundles/metrics.md
+++ b/src/main/jbake/content/documentation/bundles/metrics.md
@@ -44,12 +44,12 @@ To make use of `MetricsService`
Refer to [Metric Getting Started][2] guide to see how various types
of Metric instances can be used. Note that when using Sling Commons Metrics
-bundle class names belong to `org.apache.sling.commons.metrics` package
+bundle class names belong to the `org.apache.sling.commons.metrics` package.
## Best Practices
1. Use descriptive names - Qualify the name with class/package name where the
- metric is being used
+ metric is being used.
2. Do not use the metrics for operation which take less than 1E-7s i.e. 1000 nano
seconds otherwise timer overhead (Metrics makes use of System.nanoTime)
would start affecting the performance.
@@ -64,9 +64,33 @@ only provides methods related to data collection.
* [org.apache.sling.commons.metrics.Timer][6] - Similar to [Dropwizard Timer][dw-timer]
* [org.apache.sling.commons.metrics.Counter][5] - Similar to [Dropwizard Counter][dw-counter]
* [org.apache.sling.commons.metrics.Histogram][7] - Similar to [Dropwizard Histogram][dw-histogram]
+* [org.apache.sling.commons.metrics.Gauge][8] - Similar to [Dropwizard Gauge][dw-gauge]
Further it provides a `MetricsService` which enables creation of different
-type of Metrics like Meter, Timer, Counter and Histogram.
+type of Metrics like Meter, Timer, Counter and Histogram, Gauge.
+
+### The special case of Gauge
+
+Unlike other metric types, the gauge metric is a generic class, through which it can support many different types of gauge values.
+It can be easiest used by providing a Supplier or Lambda to return the requested value. Here the example of a gauge which returns a constant value.
+
+ ::java
+ import org.apache.sling.metrics.Gauge;
+ import org.apache.sling.metrics.MetricsService;
+
+ @Reference
+ private MetricsService metricsService;
+
+ private Gauge<Integer> cacheHitRatio;
+
+ @Activate
+ private void activate(){
+ cacheHitRatio = metricsService.counter("org.myapp.metrics.constantValue", () -> {
+ return 42;
+ });
+ }
+
+
### Requirement of wrapper interfaces
@@ -79,7 +103,7 @@ type of Metrics like Meter, Timer, Counter and Histogram.
overhead. Turning on and off can also be done on individual metric basis.
It also allows us to later extend the type of data collected. For e.g. we can also collect
-[TimerSeries][8] type of data for each metric without modifying the caller logic.
+[TimerSeries][9] type of data for each metric without modifying the caller logic.
### Access to Dropwizard Metrics API
@@ -113,29 +137,32 @@ the OSGi service registry. If the `MetricRegistry` service has a `name` property
then that would be prefixed to the Metric names from that registry. This allows
use of same name in different registry instances.
-## Installation
+## JMX support
+This library also registers all metrics as MBeans by default. That means that existing JMX-based monitoring can be used to access
+the metrics as well.
-Add following Maven dependency to your pom.xml:
+## JMX Exporter
+Starting with version 1.2.12 Sling Commons Metrics also supports the other way around. As some third-party libraries provide metrics data only via JMX, the JMX Exporter Factory can be used to export those values as metrics.
+
+Create an instance of the "JMX to Metrics Exporter" (pid: `org.apache.sling.commons.metrics.internal.JmxExporterFactory`) and provide the name of the MBean you want to export in the `objectname` property (multi-value). All attributes of these MBeans matching the following types will be exported as metrics (others are silently ignored):
+
+* Long
+* String
+* Double
+* Boolean (with [SLING-11509](https://issues.apache.org/jira/browse/SLING-11509))
- ::xml
- <dependency>
- <groupId>org.apache.sling</groupId>
- <artifactId>org.apache.sling.commons.metrics</artifactId>
- <version>1.0.0</version>
- </dependency>
-
-Or download from [here][9]
[1]: http://metrics.dropwizard.io/
-[dw-meter]: https://dropwizard.github.io/metrics/3.1.0/manual/core/#meters
-[dw-counter]: https://dropwizard.github.io/metrics/3.1.0/manual/core/#counters
-[dw-histogram]: https://dropwizard.github.io/metrics/3.1.0/manual/core/#histograms
-[dw-timer]: https://dropwizard.github.io/metrics/3.1.0/manual/core/#timers
-[2]: https://dropwizard.github.io/metrics/3.1.0/getting-started/#counters
+[dw-meter]: https://metrics.dropwizard.io/3.2.3/manual/core.html#man-core-meters
+[dw-counter]: https://metrics.dropwizard.io/3.2.3/manual/core.html#man-core-counters
+[dw-histogram]: https://metrics.dropwizard.io/3.2.3/manual/core.html#man-core-histograms
+[dw-timer]: https://metrics.dropwizard.io/3.2.3/manual/core.html#man-core-timers
+[dw-gauge]: https://metrics.dropwizard.io/3.2.3/manual/core.html#man-core-gauges
+[2]: https://dropwizard.github.io/metrics/3.2.3/getting-started/#counters
[3]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/MetricsService.java
[4]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/Meter.java
[5]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/Counter.java
[6]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/Timer.java
[7]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/Histogram.java
-[8]: https://jackrabbit.apache.org/api/2.6/org/apache/jackrabbit/api/stats/TimeSeries.html
-[9]: http://sling.apache.org/downloads.cgi
+[8]: https://github.com/apache/sling/blob/trunk/bundles/commons/metrics/src/main/java/org/apache/sling/commons/metrics/Gauge.java
+[9]: https://jackrabbit.apache.org/api/2.6/org/apache/jackrabbit/api/stats/TimeSeries.html