Benchmark.java

/**
 * Copyright 2014 Netflix, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package rx;

public final class Benchmark {
    private Benchmark() { }
    public static double measure(int count, int times, Runnable run) {
        long[] ts = new long[count];
        for (int i = 0; i < count; i++) {
            System.out.printf("%d | ", i + 1);
            System.gc();
            long start = System.nanoTime();
            try {
                run.run();
            } catch (Throwable t) {
                t.printStackTrace();
            } finally {
                start = System.nanoTime() - start;
            }
            ts[i] = start;
        }
        long sum = 0;
        int n = 0;
        for (int i = Math.max(0, count - 5); i < count; i++) {
            sum += ts[i];
            n++;
        }
        double throughput = 1E9 * n * times / sum;
        System.out.printf("| Avg.: %,.3f ops/s, %.3f ns per item%n", throughput, sum * 1d / n / times);
        return throughput;
    }
}