1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.openjdk.bench.java.util.concurrent;
  24 
  25 
  26 /**
  27  * Generic problem for concurrency tests.
  28  *
  29  * @author Aleksey Shipilev (aleksey.shipilev@oracle.com)
  30  */
  31 public class Problem {
  32 
  33     /*
  34      * Implementation notes:
  35      *
  36      * This problem makes its bidding to confuse loop unrolling and CSE, and as such break loop optimizations.
  37      * Should loop optimizations be allowed, the performance with different (l, r) could change non-linearly.
  38      */
  39 
  40     private final int[] data;
  41     private final int size;
  42 
  43     public Problem(int size) {
  44         this.size = size;
  45         data = new int[size];
  46     }
  47 
  48     public long solve() {
  49         return solve(0, size);
  50     }
  51 
  52     public long solve(int l, int r) {
  53         long sum = 0;
  54         for (int c = l; c < r; c++) {
  55             int v = hash(data[c]);
  56             if (filter(v)) {
  57                 sum += v;
  58             }
  59         }
  60         return sum;
  61     }
  62 
  63     public int size() {
  64         return size;
  65     }
  66 
  67     public static int hash(int x) {
  68         x ^= (x << 21);
  69         x ^= (x >>> 31);
  70         x ^= (x << 4);
  71         return x;
  72     }
  73 
  74     public static boolean filter(int i) {
  75         return ((i & 0b101) == 0);
  76     }
  77 
  78 }