http://metrics.dropwizard.io/metrics-core: Metrics is a Java library which gives you unparalleled insight into what your code does in production. Metrics provides a powerful toolkit of ways to measure the behavior of critical components in your production environment.
  • Coda Hale
  • Ryan Tenney
  • Artem Prigoda 
package com.codahale.metrics;



A gauge metric is an instantaneous reading of a particular value. To instrument a queue's depth,
for example:



final Queue<String> queue = new ConcurrentLinkedQueue<String>();
final Gauge<Integer> queueDepth = new Gauge<Integer>() {
    public Integer getValue() {
        return queue.size();
    }
};



Type parameters:
  • <T> – the type of the metric's value
/**
 * A gauge metric is an instantaneous reading of a particular value. To instrument a queue's depth,
 * for example:<br>
 * <pre><code>
 * final Queue&lt;String&gt; queue = new ConcurrentLinkedQueue&lt;String&gt;();
 * final Gauge&lt;Integer&gt; queueDepth = new Gauge&lt;Integer&gt;() {
 *     public Integer getValue() {
 *         return queue.size();
 *     }
 * };
 * </code></pre>
 *
 * @param <T> the type of the metric's value
 */
@FunctionalInterface
public interface Gauge<T> extends Metric {
    
Returns the metric's current value.

Returns:the metric's current value
/**
     * Returns the metric's current value.
     *
     * @return the metric's current value
     */
    T getValue();
}