/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package org.openjdk.jmh.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

AuxCounters annotation can be used to mark State objects as the bearers of auxiliary secondary results. Marking the class with this annotation will make JMH to treat its public fields and result-returning public methods as the base for the secondary benchmark metrics.
Properties:

    
Auxiliary counters are not available for every BenchmarkMode, because not every mode counts time or operations. Mode.AverageTime and Mode.Throughput are always supported.
    
AuxCounters annotation is only available for Scope.Thread state objects. It is a compile-time error to use it with other states. This means the counters are thread-local in nature.
    
Only public fields and methods are considered as metrics. If you don't want
    a field/method to be captured as metric, do not make it public.
    
Only numeric fields and numeric-returning methods are considered as metrics. These include all primitives and their corresponding boxed counterTypes, except boolean/Boolean and char/Character. It is a compile-time error to use the public field/method with incompatible type.
    
Methods with void return type are exempted from type checking. This means helper Setup and TearDown methods are fine in AuxCounters.
    
Public fields in AuxCounters instances would be reset before starting the iteration, and read back at the end of iteration. This allows benchmark code to avoid complicated lifecycle handling for these objects.
    
The counter names are generated from field/method names. The namespace for counters is shared across all states participating in the run. JMH will fail to compile the benchmark if there is an ambiguity around what counter comes from what AuxCounters class. 

CAVEAT: THIS IS AN EXPERIMENTAL API, it may be changed or removed in future
without prior warning. This is a sharp tool, use with care.
/**
 * <p>{@link AuxCounters} annotation can be used to mark {@link State} objects
 * as the bearers of auxiliary secondary results. Marking the class with this annotation
 * will make JMH to treat its public fields and result-returning public methods
 * as the base for the secondary benchmark metrics.</p>
 *
 * <p>Properties:</p>
 *
 * <ul>
 *     <li>Auxiliary counters are not available for every {@link BenchmarkMode},
 *     because not every mode counts time or operations. {@link Mode#AverageTime}
 *     and {@link Mode#Throughput} are always supported.</li>
 *
 *     <li>{@link AuxCounters} annotation is only available for {@link Scope#Thread}
 *     state objects. It is a compile-time error to use it with other states. This means
 *     the counters are thread-local in nature.</li>
 *
 *     <li>Only public fields and methods are considered as metrics. If you don't want
 *     a field/method to be captured as metric, do not make it public.</li>
 *
 *     <li>Only numeric fields and numeric-returning methods are considered as
 *     metrics. These include all primitives and their corresponding boxed counterTypes,
 *     except {@code boolean}/{@link Boolean} and {@code char}/{@link Character}.
 *     It is a compile-time error to use the public field/method with incompatible type.</li>
 *
 *     <li>Methods with {@code void} return type are exempted from type checking.
 *     This means helper {@link Setup} and {@link TearDown} methods are fine in
 *     {@link AuxCounters}.</li>
 *
 *     <li>Public fields in {@link AuxCounters} instances would be reset before
 *     starting the iteration, and read back at the end of iteration. This allows
 *     benchmark code to avoid complicated lifecycle handling for these objects.</li>
 *
 *     <li>The counter names are generated from field/method names. The namespace for
 *     counters is shared across all states participating in the run. JMH will fail to
 *     compile the benchmark if there is an ambiguity around what counter comes from
 *     what {@link AuxCounters} class.
 *     </li>
 * </ul>
 *
 * <p><b>CAVEAT: THIS IS AN EXPERIMENTAL API, it may be changed or removed in future
 * without prior warning. This is a sharp tool, use with care.</b></p>
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface AuxCounters {

    Type value() default Type.OPERATIONS;

    enum Type {
        
Counts "operations", which should be relevant to the number of times Benchmark method was executed. If this counter is incremented on each Benchmark method invocation, then it will produce a metric similar to the primary benchmark result. This counter will be normalized to benchmark time by the harness. /**
         * Counts "operations", which should be relevant to the number of
         * times {@link Benchmark} method was executed. If this counter is
         * incremented on each {@link Benchmark} method invocation, then it
         * will produce a metric similar to the primary benchmark result.
         * This counter will be normalized to benchmark time by the harness.
         */
        OPERATIONS,

        
Counts "events", the one-off things in the lifetime of workload.
This counter would not get normalized to time.
/**
         * Counts "events", the one-off things in the lifetime of workload.
         * This counter would not get normalized to time.
         */
        EVENTS,

        ;
    }
}