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 statistically representative reservoir of a data stream.

/**
 * A statistically representative reservoir of a data stream.
 */
public interface Reservoir {
    
Returns the number of values recorded.

Returns:the number of values recorded
/**
     * Returns the number of values recorded.
     *
     * @return the number of values recorded
     */
    int size();

    
Adds a new recorded value to the reservoir.

Params:
  • value – a new recorded value
/**
     * Adds a new recorded value to the reservoir.
     *
     * @param value a new recorded value
     */
    void update(long value);

    
Returns a snapshot of the reservoir's values.

Returns:a snapshot of the reservoir's values
/**
     * Returns a snapshot of the reservoir's values.
     *
     * @return a snapshot of the reservoir's values
     */
    Snapshot getSnapshot();
}