1 /* 2 * Copyright (C) 2009 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.caliper; 18 19 import java.lang.annotation.ElementType; 20 import java.lang.annotation.Retention; 21 import java.lang.annotation.RetentionPolicy; 22 import java.lang.annotation.Target; 23 24 /** 25 * To make your benchmark depend on a parameterized value, create a field with the name you want 26 * this parameter to be known by, and add this annotation. Caliper will inject a value for this 27 * field to each instance it creates. These values come from 28 * 29 * <ul> 30 * <li>The command line, if specified using {@code -Dname=value1,value2,value3} 31 * <li>Otherwise, the {@link #value()} list given in the annotation 32 * <li>Otherwise, if the parameter type is either {@code boolean} or an {@code enum} type, Caliper 33 * assumes you want all possible values. 34 * <li>Finally, if none of the above match, Caliper will display an error and exit. 35 * </ul> 36 * 37 * <p>Caliper parameters are always strings, but can be converted to other types at the point of 38 * injection. If the type of the field this annotation is applied to is not {@link String}, then the 39 * type class must contain a static {@code fromString(String)}, {@code decode(String)} or {@code 40 * valueOf(String)} method that returns that type, or a constructor accepting only a {@code String}. 41 * 42 * <p>Caliper will test every possible combination of parameter values for your benchmark. For 43 * example, if you have two parameters, {@code -Dletter=a,b,c -Dnumber=1,2}, Caliper will construct 44 * six independent "scenarios" and perform measurement for each one. 45 */ 46 @Retention(RetentionPolicy.RUNTIME) 47 @Target(ElementType.FIELD) 48 public @interface Param { 49 /** 50 * One or more default values, as strings, that this parameter should be given if none are 51 * specified on the command line. If values are specified on the command line, the defaults given 52 * here are all ignored. 53 */ value()54 String[] value() default {}; 55 } 56