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Diffstat (limited to 'kamon-annotation/src/main/java/kamon/annotation/Histogram.java')
| -rw-r--r-- | kamon-annotation/src/main/java/kamon/annotation/Histogram.java | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/kamon-annotation/src/main/java/kamon/annotation/Histogram.java b/kamon-annotation/src/main/java/kamon/annotation/Histogram.java new file mode 100644 index 00000000..7c163104 --- /dev/null +++ b/kamon-annotation/src/main/java/kamon/annotation/Histogram.java @@ -0,0 +1,89 @@ +/* + * ========================================================================================= + * Copyright © 2013-2015 the kamon project <http://kamon.io/> + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software distributed under the + * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, + * either express or implied. See the License for the specific language governing permissions + * and limitations under the License. + * ========================================================================================= + */ + +package kamon.annotation; + +import java.lang.annotation.*; + +/** + * A marker annotation to define a method as a Histogram. + * <p> + * <p> + * Given a method like this: + * <pre><code> + * {@literal @}0Histogram(name = "coolName", tags="${'my-cool-tag':'my-cool-value'}") + * public (Long|Double|Float|Integer) coolName() { + * return someComputation(); + * } + * </code></pre> + * <p> + * <p> + * A {@link kamon.metric.instrument.Histogram Histogram} for the defining method with the name {@code coolName} will be created which uses the + * annotated method's return as its value. + */ +@Documented +@Target(ElementType.METHOD) +@Retention(RetentionPolicy.RUNTIME) +public @interface Histogram { + + /** + * @return The histogram's name. + * <p> + * Also, the Metric name can be resolved with an EL expression that evaluates to a String: + * <p> + * <pre> + * {@code + * class ClassWithHistogram { + * private long id; + * + * public long getId() { return id; } + * + * {@literal @}Histogram (name = "${'histoID:' += this.id}") + * void countedMethod() {} // create a histogram with name => histoID:[id] + * } + * } + * </pre> + */ + String name(); + + /** + * The lowest value that can be discerned (distinguished from 0) by the histogram.Must be a positive integer that + * is >= 1. May be internally rounded down to nearest power of 2. + */ + long lowestDiscernibleValue() default 1; + + + /** + * The highest value to be tracked by the histogram. Must be a positive integer that is >= (2 * lowestDiscernibleValue). + * Must not be larger than (Long.MAX_VALUE/2). + */ + long highestTrackableValue() default 3600000000000L; + + /** + * The number of significant decimal digits to which the histogram will maintain value resolution and separation. + * Must be a non-negative integer between 1 and 3. + */ + int precision() default 2; + + + /** + * Tags are a way of adding dimensions to metrics, + * these are constructed using EL syntax e.g. "${'algorithm':'1','env':'production'}" + * + * @return the tags associated to the histogram + */ + String tags() default ""; +}
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