1/*
2 * Copyright (c) 2014, 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_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP
26#define SHARE_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP
27
28#include "gc/shared/concurrentGCThread.hpp"
29#include "gc/shared/stringdedup/stringDedupStat.hpp"
30
31//
32// The deduplication thread is where the actual deduplication occurs. It waits for
33// deduplication candidates to appear on the deduplication queue, removes them from
34// the queue and tries to deduplicate them. It uses the deduplication hashtable to
35// find identical, already existing, character arrays on the heap. The thread runs
36// concurrently with the Java application but participates in safepoints to allow
37// the GC to adjust and unlink oops from the deduplication queue and table.
38//
39class StringDedupThread: public ConcurrentGCThread {
40protected:
41 static StringDedupThread* _thread;
42
43 StringDedupThread();
44 ~StringDedupThread();
45
46 void print_start(const StringDedupStat* last_stat);
47 void print_end(const StringDedupStat* last_stat, const StringDedupStat* total_stat);
48
49 void run_service() { this->do_deduplication(); }
50 void stop_service();
51
52 void deduplicate_shared_strings(StringDedupStat* stat);
53protected:
54 virtual void do_deduplication() = 0;
55
56public:
57 static StringDedupThread* thread();
58};
59
60template <typename S>
61class StringDedupThreadImpl : public StringDedupThread {
62private:
63 StringDedupThreadImpl() { }
64
65protected:
66 void do_deduplication();
67
68public:
69 static void create();
70};
71
72#endif // SHARE_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP
73