1 /*
   2  * Copyright (c) 2015, 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  */
  24 
  25 #include "precompiled.hpp"
  26 #include "utilities/debug.hpp"
  27 #include "runtime/semaphore.hpp"
  28 
  29 // Implements the limited, platform independent Semaphore API.
  30 Semaphore::Semaphore(uint value) : _impl(value) {}
  31 Semaphore::~Semaphore()            {}
  32 void Semaphore::signal(uint count) { _impl.signal(count); }
  33 void Semaphore::wait()             { _impl.wait(); }
  34 
  35 /////////////// Unit tests ///////////////
  36 
  37 #ifndef PRODUCT
  38 
  39 static void test_semaphore_single_separate(uint count) {
  40   Semaphore sem(0);
  41 
  42   for (uint i = 0; i < count; i++) {
  43     sem.signal();
  44   }
  45 
  46   for (uint i = 0; i < count; i++) {
  47     sem.wait();
  48   }
  49 }
  50 
  51 static void test_semaphore_single_combined(uint count) {
  52   Semaphore sem(0);
  53 
  54   for (uint i = 0; i < count; i++) {
  55     sem.signal();
  56     sem.wait();
  57   }
  58 }
  59 
  60 static void test_semaphore_many(uint value, uint max, uint increments) {
  61   Semaphore sem(value);
  62 
  63   uint total = value;
  64 
  65   for (uint i = value; i + increments <= max; i += increments) {
  66     sem.signal(increments);
  67 
  68     total += increments;
  69   }
  70 
  71   for (uint i = 0; i < total; i++) {
  72     sem.wait();
  73   }
  74 }
  75 
  76 static void test_semaphore_many() {
  77   for (uint max = 0; max < 10; max++) {
  78     for (uint value = 0; value < max; value++) {
  79       for (uint inc = 1; inc <= max - value; inc++) {
  80         test_semaphore_many(value, max, inc);
  81       }
  82     }
  83   }
  84 }
  85 
  86 void test_semaphore() {
  87   for (uint i = 1; i < 10; i++) {
  88     test_semaphore_single_separate(i);
  89   }
  90 
  91   for (uint i = 0; i < 10; i++) {
  92     test_semaphore_single_combined(i);
  93   }
  94 
  95   test_semaphore_many();
  96 }
  97 
  98 #endif // PRODUCT
  99