1/*
2 * Copyright (c) 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.
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23 */
24
25#ifndef SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
26#define SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
27
28#include "memory/allocation.hpp"
29#include "runtime/semaphore.hpp"
30
31// In addition to the barrier tag, it uses two counters to keep the semaphore
32// count correct and not leave any late thread waiting.
33class GenericWaitBarrier : public CHeapObj<mtInternal> {
34 volatile int _barrier_tag;
35 // The number of threads waiting on or about to wait on the semaphore.
36 volatile int _waiters;
37 // The number of threads in the wait path, before or after the tag check.
38 // These threads can become waiters.
39 volatile int _barrier_threads;
40 Semaphore _sem_barrier;
41
42 // Prevent copying and assignment of GenericWaitBarrier instances.
43 GenericWaitBarrier(const GenericWaitBarrier&);
44 GenericWaitBarrier& operator=(const GenericWaitBarrier&);
45
46 int wake_if_needed();
47
48 public:
49 GenericWaitBarrier() : _barrier_tag(0), _waiters(0), _barrier_threads(0), _sem_barrier(0) {}
50 ~GenericWaitBarrier() {}
51
52 const char* description() { return "semaphore"; }
53
54 void arm(int barrier_tag);
55 void disarm();
56 void wait(int barrier_tag);
57};
58
59#endif // SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
60