org.eclipse.microprofile.metrics.annotation.Gauge Maven / Gradle / Ivy
/*
**********************************************************************
* Copyright (c) 2017, 2022 Contributors to the Eclipse Foundation
* 2010-2013 Coda Hale, Yammer.com
*
* See the NOTICES file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
**********************************************************************/
package org.eclipse.microprofile.metrics.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.eclipse.microprofile.metrics.MetricRegistry;
import jakarta.enterprise.util.Nonbinding;
import jakarta.interceptor.InterceptorBinding;
/**
* An annotation for marking a method or field as a gauge. The metric will be registered in the application
* MetricRegistry.
*
*
* Given a method annotated with {@literal @}Gauge like this:
*
*
*
*
* {@literal @}Gauge(name = "queueSize")
* public int getQueueSize() {
* return queue.size;
* }
*
*
*
* A gauge with the fully qualified class name + {@code queueSize} will be created which uses the annotated method's
* return value as its value.
*
* The annotated method/field must be of numeric type (extends {@link java.lang.Number}).
*
*/
@InterceptorBinding
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
public @interface Gauge {
/**
* The name of the gauge.
*
* @return The name of the gauge.
*/
@Nonbinding
String name() default "";
/**
* The tags of the gauge.
*
* @return The tags of the gauge. Each {@code String} tag must be in the form of 'key=value'. If the input is empty
* or does not contain a '=' sign, the entry is ignored.
*
* @see org.eclipse.microprofile.metrics.Metadata
*/
@Nonbinding
String[] tags() default {};
/**
* Denotes whether to use the absolute name or use the default given name relative to the annotated class.
*
* @return If {@code true}, use the given name as an absolute name. If {@code false} (default), use the given name
* relative to the annotated class.
*/
@Nonbinding
boolean absolute() default false;
/**
* The description of the gauge.
*
* @return The description of the gauge.
*
* @see org.eclipse.microprofile.metrics.Metadata
*/
@Nonbinding
String description() default "";
/**
* The unit of the gauge.
*
* @return (Required) The unit of the gauge.
*
* @see org.eclipse.microprofile.metrics.Metadata
* @see org.eclipse.microprofile.metrics.MetricUnits
*/
@Nonbinding
String unit();
/**
* The scope that this gauge belongs to.
*
* @return The scope this gauge belongs to. By default, the value is {@link MetricRegistry#APPLICATION_SCOPE}.
*
*/
@Nonbinding
String scope() default MetricRegistry.APPLICATION_SCOPE;
}