NamedLambdaJMH

# Run complete. Total time: 00:40:31

Benchmark                        Mode  Cnt          Score         Error  Units
MyBenchmark.testNamedPredicate  thrpt  200   45938970,625 ±  615390,483  ops/s
MyBenchmark.testPredicate       thrpt  200   23062083,641 ±  154933,675  ops/s
MyBenchmark.testPredicateReal   thrpt  200   48308347,165 ±  395810,356  ops/s
MyBenchmark.testToString        thrpt  200  138366708,182 ± 1177786,195  ops/s
MyBenchmark.testToStringNamed   thrpt  200  252872229,907 ± 8044289,516  ops/s
MyBenchmark.testToStringReal    thrpt  200    6670148,202 ±   40200,984  ops/s

------- MyBenchmark.java ----

/*
 * Copyright (c) 2014, Oracle America, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 *  * Neither the name of Oracle nor the names of its contributors may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package inc.lambdahelpers;

import java.util.function.Predicate;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;

@State(Scope.Benchmark)
public class MyBenchmark {
	
	private Predicate<String> realP = (s) ->  !s.trim().isEmpty();
	private Predicate<String> p = LambdaNamer.nameIt("isNotEmpty", realP);
	private Predicate<String> namedP = LambdaNamer.namedPredicate("isNotEmpty", realP);

	private String testString1 = "Hello";
	private String testString2 = "     ";
	
	
    @Benchmark
    public int testPredicate() {
    	 int result = 0;
    	 result += p.test(testString1) ? 1 : 0 ;
    	 result += p.test(testString2) ? 1 : 0 ;
    	 return result;
    }
    
    @Benchmark
    public int testPredicateReal() {
    	 int result = 0;
    	 result += realP.test(testString1) ? 1 : 0 ;
    	 result += realP.test(testString2) ? 1 : 0 ;
    	 return result;
    }

    @Benchmark
    public int testNamedPredicate() {
    	 int result = 0;
    	 result += namedP.test(testString1) ? 1 : 0 ;
    	 result += namedP.test(testString2) ? 1 : 0 ;
    	 return result;
    }

    @Benchmark
    public String testToString() {
    	 return p.toString();
    }

    @Benchmark
    public String testToStringReal() {
    	 return realP.toString();
    }

    @Benchmark
    public String testToStringNamed() {
    	 return namedP.toString();
    }
}


-----LambdaNamer.java--------

import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
 * Helper Class to give lambda a name ("toString") for debugging purpose
 *
 */
public class LambdaNamer {

    private static Method TO_STRING;

    static {
        try {
            TO_STRING = Object.class.getMethod("toString");
        } catch (NoSuchMethodException | SecurityException e) {
            throw new RuntimeException("There is something rotten in state of denmark!");
        }
    }

    /**
     * Overrides toString "Method" for a given lambda.
     * 
     * @param name toString result of lambda
     * @param obj the lambda to encapsulate
     * @return the named lambda
     */
    public static <T> T nameIt(String name, T obj) {
        if (Boolean.getBoolean("namedLambdasEnabled")) {
            Class<T> clazz = (Class<T>) obj.getClass();
            Class<?>[] interfaces = clazz.getInterfaces();

            return (T) Proxy.newProxyInstance(//
                    obj.getClass().getClassLoader(),//
                    interfaces, //
                    (Object proxy, Method method, Object[] args) -> {
                        if (TO_STRING.equals(method)) {
                            return name;
                        } else {
                            return method.invoke(obj, args);
                        }
                    });
        } else {
            return obj;
        }
    }
    
    public static <T> Predicate<T> namedPredicate(String name, Predicate<? super T> pred) {
        return new Predicate<T>() {
            public String toString() { return name; }
            public boolean test(T t) { return pred.test(t); }
        };
    }
    
}