1 /*
   2  * Copyright (c) 2018, 2019, 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 "runtime/interfaceSupport.inline.hpp"
  27 #include "runtime/atomic.hpp"
  28 #include "runtime/os.hpp"
  29 #include "runtime/thread.hpp"
  30 #include "utilities/debug.hpp"
  31 #include "utilities/globalCounter.inline.hpp"
  32 #include "utilities/globalDefinitions.hpp"
  33 #include "utilities/ostream.hpp"
  34 #include "utilities/singleWriterSynchronizer.hpp"
  35 #include "threadHelper.inline.hpp"
  36 #include "unittest.hpp"
  37 
  38 class SingleWriterSynchronizerTestReader : public JavaTestThread {
  39   SingleWriterSynchronizer* _synchronizer;
  40   volatile uintx* _synchronized_value;
  41   volatile int* _continue_running;
  42 
  43   static const uint reader_iterations = 10;
  44 
  45 public:
  46   SingleWriterSynchronizerTestReader(Semaphore* post,
  47                                      SingleWriterSynchronizer* synchronizer,
  48                                      volatile uintx* synchronized_value,
  49                                      volatile int* continue_running) :
  50     JavaTestThread(post),
  51     _synchronizer(synchronizer),
  52     _synchronized_value(synchronized_value),
  53     _continue_running(continue_running)
  54   {}
  55 
  56   virtual void main_run() {
  57     size_t iterations = 0;
  58     size_t values_changed = 0;
  59     while (Atomic::load_acquire(_continue_running) != 0) {
  60       { ThreadBlockInVM tbiv(this); } // Safepoint check outside critical section.
  61       ++iterations;
  62       SingleWriterSynchronizer::CriticalSection cs(_synchronizer);
  63       uintx value = Atomic::load_acquire(_synchronized_value);
  64       uintx new_value = value;
  65       for (uint i = 0; i < reader_iterations; ++i) {
  66         new_value = Atomic::load_acquire(_synchronized_value);
  67         // A reader can see either the value it first read after
  68         // entering the critical section, or that value + 1.  No other
  69         // values are possible.
  70         if (value != new_value) {
  71           ASSERT_EQ((value + 1), new_value);
  72         }
  73       }
  74       if (value != new_value) {
  75         ++values_changed;
  76       }
  77     }
  78     tty->print_cr("reader iterations: " SIZE_FORMAT ", changes: " SIZE_FORMAT,
  79                   iterations, values_changed);
  80   }
  81 };
  82 
  83 class SingleWriterSynchronizerTestWriter : public JavaTestThread {
  84   SingleWriterSynchronizer* _synchronizer;
  85   volatile uintx* _synchronized_value;
  86   volatile int* _continue_running;
  87 
  88 public:
  89   SingleWriterSynchronizerTestWriter(Semaphore* post,
  90                                      SingleWriterSynchronizer* synchronizer,
  91                                      volatile uintx* synchronized_value,
  92                                      volatile int* continue_running) :
  93     JavaTestThread(post),
  94     _synchronizer(synchronizer),
  95     _synchronized_value(synchronized_value),
  96     _continue_running(continue_running)
  97   {}
  98 
  99   virtual void main_run() {
 100     while (Atomic::load_acquire(_continue_running) != 0) {
 101       ++*_synchronized_value;
 102       _synchronizer->synchronize();
 103       { ThreadBlockInVM tbiv(this); } // Safepoint check.
 104     }
 105     tty->print_cr("writer iterations: " UINTX_FORMAT, *_synchronized_value);
 106   }
 107 };
 108 
 109 const uint nreaders = 5;
 110 const uint milliseconds_to_run = 1000;
 111 
 112 TEST_VM(TestSingleWriterSynchronizer, stress) {
 113   Semaphore post;
 114   SingleWriterSynchronizer synchronizer;
 115   volatile uintx synchronized_value = 0;
 116   volatile int continue_running = 1;
 117 
 118   JavaTestThread* readers[nreaders] = {};
 119   for (uint i = 0; i < nreaders; ++i) {
 120     readers[i] = new SingleWriterSynchronizerTestReader(&post,
 121                                                         &synchronizer,
 122                                                         &synchronized_value,
 123                                                         &continue_running);
 124     readers[i]->doit();
 125   }
 126 
 127   JavaTestThread* writer =
 128     new SingleWriterSynchronizerTestWriter(&post,
 129                                            &synchronizer,
 130                                            &synchronized_value,
 131                                            &continue_running);
 132 
 133   writer->doit();
 134 
 135   tty->print_cr("Stressing synchronizer for %u ms", milliseconds_to_run);
 136   JavaThread* cur = JavaThread::current();
 137   {
 138     ThreadInVMfromNative invm(cur);
 139     cur->sleep(milliseconds_to_run);
 140   }
 141   continue_running = 0;
 142   for (uint i = 0; i < nreaders + 1; ++i) {
 143     post.wait();
 144   }
 145 }