com.hazelcast.internal.metrics.Metric Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2015, 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.internal.metrics;
/**
* Each metric is uniquely identified using a name. See {@link #getName()}.
*
* A metric gets its content from Probes. An input can be one of the following:
*
* - a method with the {@link Probe} annotation
* - a field with the {@link Probe} annotation
* - a {@link LongProbe} function
* - a {@link DoubleProbe} function
*
*
* If the Metric is obtained before it is registered, the Metric is without input. As soon as the registration happens, the
* input is set on the metric and the current information will be retrieved.
*/
public interface Metric {
/**
* Gets the name that identifies this metric. The returned value will never change and never be null.
*
* @return the name of the metric.
*/
String getName();
/**
* Renders the metric.
*
* @param sb the StringBuilder to write to.
* @throws NullPointerException if sb is null
*/
void render(StringBuilder sb);
}