1 /*
2 * Copyright (c) 2021, 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 "gc/shared/stringdedup/stringDedupStorageUse.hpp"
27 #include "runtime/atomic.hpp"
28 #include "runtime/thread.hpp"
29 #include "utilities/debug.hpp"
30 #include "utilities/globalCounter.inline.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
StorageUse(OopStorage * storage)33 StringDedup::StorageUse::StorageUse(OopStorage* storage) :
34 _storage(storage), _use_count(0)
35 {}
36
is_used_acquire() const37 bool StringDedup::StorageUse::is_used_acquire() const {
38 return Atomic::load_acquire(&_use_count) > 0;
39 }
40
41 StringDedup::StorageUse*
obtain(StorageUse * volatile * ptr)42 StringDedup::StorageUse::obtain(StorageUse* volatile* ptr) {
43 GlobalCounter::CriticalSection cs(Thread::current());
44 StorageUse* storage = Atomic::load(ptr);
45 Atomic::inc(&storage->_use_count);
46 return storage;
47 }
48
relinquish()49 void StringDedup::StorageUse::relinquish() {
50 size_t result = Atomic::sub(&_use_count, size_t(1));
51 assert(result != SIZE_MAX, "use count underflow");
52 }
53