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.
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 "classfile/javaClasses.inline.hpp"
27#include "gc/g1/g1CollectedHeap.inline.hpp"
28#include "gc/g1/g1GCPhaseTimes.hpp"
29#include "gc/g1/g1StringDedup.hpp"
30#include "gc/g1/g1StringDedupQueue.hpp"
31#include "gc/g1/g1StringDedupStat.hpp"
32#include "gc/shared/stringdedup/stringDedup.inline.hpp"
33#include "gc/shared/stringdedup/stringDedupQueue.hpp"
34#include "gc/shared/stringdedup/stringDedupTable.hpp"
35#include "gc/shared/stringdedup/stringDedupThread.inline.hpp"
36#include "oops/oop.inline.hpp"
37#include "runtime/atomic.hpp"
38
39void G1StringDedup::initialize() {
40 assert(UseG1GC, "String deduplication available with G1");
41 StringDedup::initialize_impl<G1StringDedupQueue, G1StringDedupStat>();
42}
43
44bool G1StringDedup::is_candidate_from_mark(oop obj) {
45 if (java_lang_String::is_instance_inlined(obj)) {
46 bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young();
47 if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
48 // Candidate found. String is being evacuated from young to old but has not
49 // reached the deduplication age threshold, i.e. has not previously been a
50 // candidate during its life in the young generation.
51 return true;
52 }
53 }
54
55 // Not a candidate
56 return false;
57}
58
59void G1StringDedup::enqueue_from_mark(oop java_string, uint worker_id) {
60 assert(is_enabled(), "String deduplication not enabled");
61 if (is_candidate_from_mark(java_string)) {
62 G1StringDedupQueue::push(worker_id, java_string);
63 }
64}
65
66bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {
67 if (from_young && java_lang_String::is_instance_inlined(obj)) {
68 if (to_young && obj->age() == StringDeduplicationAgeThreshold) {
69 // Candidate found. String is being evacuated from young to young and just
70 // reached the deduplication age threshold.
71 return true;
72 }
73 if (!to_young && obj->age() < StringDeduplicationAgeThreshold) {
74 // Candidate found. String is being evacuated from young to old but has not
75 // reached the deduplication age threshold, i.e. has not previously been a
76 // candidate during its life in the young generation.
77 return true;
78 }
79 }
80
81 // Not a candidate
82 return false;
83}
84
85void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) {
86 assert(is_enabled(), "String deduplication not enabled");
87 if (is_candidate_from_evacuation(from_young, to_young, java_string)) {
88 G1StringDedupQueue::push(worker_id, java_string);
89 }
90}
91
92