com.hazelcast.jet.core.metrics.Metric Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2023, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.jet.core.metrics;
import javax.annotation.Nonnull;
/**
* Handler for manipulating one user-defined metric.
*
* Metrics are in essence just simple {@code long} values, with any semantics.
* They can be used for example for counting things (like number of certain
* events) or for storing standalone values (like measurements).
*
* To obtain an instance, use {@link Metrics#metric}. The instance is tied to
* the processor it was created for and is or is not thread-safe based on the
* method that was used to create it.
*
* @since Jet 4.0
*/
public interface Metric {
/**
* Returns the name of the associated metric.
*/
@Nonnull
String name();
/**
* Return the measurement unit for the associated metric. Meant
* to provide further information on the type of value measured
* by the user-defined metric. Doesn't affect the functionality of the
* metric, it still remains a simple numeric value, but is used to
* populate the {@link MetricTags#UNIT} tag in the metric's description.
*/
@Nonnull
Unit unit();
/**
* Increments the current value by 1.
*/
void increment();
/**
* Increments the current value by the specified amount.
*/
void increment(long amount);
/**
* Decrements the current value by 1.
*/
void decrement();
/**
* Decrements the current value by the specified amount.
*/
void decrement(long amount);
/**
* Sets the current value.
*/
void set(long newValue);
}