17764
|
1 /*
|
|
2 * Copyright (c) 2014, 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.hpp"
|
|
27 #include "gc_implementation/g1/g1StringDedupQueue.hpp"
|
|
28 #include "memory/gcLocker.hpp"
|
|
29 #include "runtime/mutexLocker.hpp"
|
|
30 #include "utilities/stack.inline.hpp"
|
|
31
|
|
32 G1StringDedupQueue* G1StringDedupQueue::_queue = NULL;
|
|
33 const size_t G1StringDedupQueue::_max_size = 1000000; // Max number of elements per queue
|
|
34 const size_t G1StringDedupQueue::_max_cache_size = 0; // Max cache size per queue
|
|
35
|
|
36 G1StringDedupQueue::G1StringDedupQueue() :
|
|
37 _cursor(0),
|
|
38 _empty(true),
|
|
39 _dropped(0) {
|
|
40 _nqueues = MAX2(ParallelGCThreads, (size_t)1);
|
|
41 _queues = NEW_C_HEAP_ARRAY(G1StringDedupWorkerQueue, _nqueues, mtGC);
|
|
42 for (size_t i = 0; i < _nqueues; i++) {
|
|
43 new (_queues + i) G1StringDedupWorkerQueue(G1StringDedupWorkerQueue::default_segment_size(), _max_cache_size, _max_size);
|
|
44 }
|
|
45 }
|
|
46
|
|
47 G1StringDedupQueue::~G1StringDedupQueue() {
|
|
48 ShouldNotReachHere();
|
|
49 }
|
|
50
|
|
51 void G1StringDedupQueue::create() {
|
|
52 assert(_queue == NULL, "One string deduplication queue allowed");
|
|
53 _queue = new G1StringDedupQueue();
|
|
54 }
|
|
55
|
|
56 void G1StringDedupQueue::wait() {
|
|
57 MonitorLockerEx ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);
|
|
58 while (_queue->_empty) {
|
|
59 ml.wait(Mutex::_no_safepoint_check_flag);
|
|
60 }
|
|
61 }
|
|
62
|
|
63 void G1StringDedupQueue::push(uint worker_id, oop java_string) {
|
|
64 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
|
|
65 assert(worker_id < _queue->_nqueues, "Invalid queue");
|
|
66
|
|
67 // Push and notify waiter
|
|
68 G1StringDedupWorkerQueue& worker_queue = _queue->_queues[worker_id];
|
|
69 if (!worker_queue.is_full()) {
|
|
70 worker_queue.push(java_string);
|
|
71 if (_queue->_empty) {
|
|
72 MonitorLockerEx ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);
|
|
73 if (_queue->_empty) {
|
|
74 // Mark non-empty and notify waiter
|
|
75 _queue->_empty = false;
|
|
76 ml.notify();
|
|
77 }
|
|
78 }
|
|
79 } else {
|
|
80 // Queue is full, drop the string and update the statistics
|
|
81 Atomic::inc_ptr(&_queue->_dropped);
|
|
82 }
|
|
83 }
|
|
84
|
|
85 oop G1StringDedupQueue::pop() {
|
|
86 assert(!SafepointSynchronize::is_at_safepoint(), "Must not be at safepoint");
|
|
87 No_Safepoint_Verifier nsv;
|
|
88
|
|
89 // Try all queues before giving up
|
|
90 for (size_t tries = 0; tries < _queue->_nqueues; tries++) {
|
|
91 // The cursor indicates where we left of last time
|
|
92 G1StringDedupWorkerQueue* queue = &_queue->_queues[_queue->_cursor];
|
|
93 while (!queue->is_empty()) {
|
|
94 oop obj = queue->pop();
|
|
95 // The oop we pop can be NULL if it was marked
|
|
96 // dead. Just ignore those and pop the next oop.
|
|
97 if (obj != NULL) {
|
|
98 return obj;
|
|
99 }
|
|
100 }
|
|
101
|
|
102 // Try next queue
|
|
103 _queue->_cursor = (_queue->_cursor + 1) % _queue->_nqueues;
|
|
104 }
|
|
105
|
|
106 // Mark empty
|
|
107 _queue->_empty = true;
|
|
108
|
|
109 return NULL;
|
|
110 }
|
|
111
|
|
112 void G1StringDedupQueue::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl) {
|
|
113 // A worker thread first claims a queue, which ensures exclusive
|
|
114 // access to that queue, then continues to process it.
|
|
115 for (;;) {
|
|
116 // Grab next queue to scan
|
|
117 size_t queue = cl->claim_queue();
|
|
118 if (queue >= _queue->_nqueues) {
|
|
119 // End of queues
|
|
120 break;
|
|
121 }
|
|
122
|
|
123 // Scan the queue
|
|
124 unlink_or_oops_do(cl, queue);
|
|
125 }
|
|
126 }
|
|
127
|
|
128 void G1StringDedupQueue::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl, size_t queue) {
|
|
129 assert(queue < _queue->_nqueues, "Invalid queue");
|
|
130 StackIterator<oop, mtGC> iter(_queue->_queues[queue]);
|
|
131 while (!iter.is_empty()) {
|
|
132 oop* p = iter.next_addr();
|
|
133 if (*p != NULL) {
|
|
134 if (cl->is_alive(*p)) {
|
|
135 cl->keep_alive(p);
|
|
136 } else {
|
|
137 // Clear dead reference
|
|
138 *p = NULL;
|
|
139 }
|
|
140 }
|
|
141 }
|
|
142 }
|
|
143
|
|
144 void G1StringDedupQueue::print_statistics(outputStream* st) {
|
|
145 st->print_cr(
|
|
146 " [Queue]\n"
|
|
147 " [Dropped: "UINTX_FORMAT"]", _queue->_dropped);
|
|
148 }
|
|
149
|
|
150 void G1StringDedupQueue::verify() {
|
|
151 for (size_t i = 0; i < _queue->_nqueues; i++) {
|
|
152 StackIterator<oop, mtGC> iter(_queue->_queues[i]);
|
|
153 while (!iter.is_empty()) {
|
|
154 oop obj = iter.next();
|
|
155 if (obj != NULL) {
|
|
156 guarantee(Universe::heap()->is_in_reserved(obj), "Object must be on the heap");
|
|
157 guarantee(!obj->is_forwarded(), "Object must not be forwarded");
|
|
158 guarantee(java_lang_String::is_instance(obj), "Object must be a String");
|
|
159 }
|
|
160 }
|
|
161 }
|
|
162 }
|