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comparison src/share/vm/gc_implementation/g1/ptrQueue.cpp @ 342:37f87013dfd8

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6711316: Open source the Garbage-First garbage collector Summary: First mercurial integration of the code for the Garbage-First garbage collector. Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author ysr
date Thu, 05 Jun 2008 15:57:56 -0700
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children da9cb4e97a5f
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189:0b27f3512f9e 342:37f87013dfd8
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_ptrQueue.cpp.incl"
27
28 PtrQueue::PtrQueue(PtrQueueSet* qset_, bool perm) :
29 _qset(qset_), _buf(NULL), _index(0), _active(false),
30 _perm(perm), _lock(NULL)
31 {}
32
33 PtrQueue::~PtrQueue() {
34 if (!_perm && _buf != NULL) {
35 if (_index == _sz) {
36 // No work to do.
37 qset()->deallocate_buffer(_buf);
38 } else {
39 // We must NULL out the unused entries, then enqueue.
40 for (size_t i = 0; i < _index; i += oopSize) {
41 _buf[byte_index_to_index((int)i)] = NULL;
42 }
43 qset()->enqueue_complete_buffer(_buf);
44 _buf = NULL;
45 }
46 }
47 }
48
49
50 static int byte_index_to_index(int ind) {
51 assert((ind % oopSize) == 0, "Invariant.");
52 return ind / oopSize;
53 }
54
55 static int index_to_byte_index(int byte_ind) {
56 return byte_ind * oopSize;
57 }
58
59 void PtrQueue::enqueue_known_active(void* ptr) {
60 assert(0 <= _index && _index <= _sz, "Invariant.");
61 assert(_index == 0 || _buf != NULL, "invariant");
62
63 while (_index == 0) {
64 handle_zero_index();
65 }
66 assert(_index > 0, "postcondition");
67
68 _index -= oopSize;
69 _buf[byte_index_to_index((int)_index)] = ptr;
70 assert(0 <= _index && _index <= _sz, "Invariant.");
71 }
72
73 void PtrQueue::locking_enqueue_completed_buffer(void** buf) {
74 assert(_lock->owned_by_self(), "Required.");
75 _lock->unlock();
76 qset()->enqueue_complete_buffer(buf);
77 // We must relock only because the caller will unlock, for the normal
78 // case.
79 _lock->lock_without_safepoint_check();
80 }
81
82
83 PtrQueueSet::PtrQueueSet(bool notify_when_complete) :
84 _max_completed_queue(0),
85 _cbl_mon(NULL), _fl_lock(NULL),
86 _notify_when_complete(notify_when_complete),
87 _sz(0),
88 _completed_buffers_head(NULL),
89 _completed_buffers_tail(NULL),
90 _n_completed_buffers(0),
91 _process_completed_threshold(0), _process_completed(false),
92 _buf_free_list(NULL), _buf_free_list_sz(0)
93 {}
94
95 void** PtrQueueSet::allocate_buffer() {
96 assert(_sz > 0, "Didn't set a buffer size.");
97 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
98 if (_buf_free_list != NULL) {
99 void** res = _buf_free_list;
100 _buf_free_list = (void**)_buf_free_list[0];
101 _buf_free_list_sz--;
102 // Just override the next pointer with NULL, just in case we scan this part
103 // of the buffer.
104 res[0] = NULL;
105 return res;
106 } else {
107 return NEW_C_HEAP_ARRAY(void*, _sz);
108 }
109 }
110
111 void PtrQueueSet::deallocate_buffer(void** buf) {
112 assert(_sz > 0, "Didn't set a buffer size.");
113 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
114 buf[0] = (void*)_buf_free_list;
115 _buf_free_list = buf;
116 _buf_free_list_sz++;
117 }
118
119 void PtrQueueSet::reduce_free_list() {
120 // For now we'll adopt the strategy of deleting half.
121 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
122 size_t n = _buf_free_list_sz / 2;
123 while (n > 0) {
124 assert(_buf_free_list != NULL, "_buf_free_list_sz must be wrong.");
125 void** head = _buf_free_list;
126 _buf_free_list = (void**)_buf_free_list[0];
127 FREE_C_HEAP_ARRAY(void*,head);
128 n--;
129 }
130 }
131
132 void PtrQueueSet::enqueue_complete_buffer(void** buf, size_t index, bool ignore_max_completed) {
133 // I use explicit locking here because there's a bailout in the middle.
134 _cbl_mon->lock_without_safepoint_check();
135
136 Thread* thread = Thread::current();
137 assert( ignore_max_completed ||
138 thread->is_Java_thread() ||
139 SafepointSynchronize::is_at_safepoint(),
140 "invariant" );
141 ignore_max_completed = ignore_max_completed || !thread->is_Java_thread();
142
143 if (!ignore_max_completed && _max_completed_queue > 0 &&
144 _n_completed_buffers >= (size_t) _max_completed_queue) {
145 _cbl_mon->unlock();
146 bool b = mut_process_buffer(buf);
147 if (b) {
148 deallocate_buffer(buf);
149 return;
150 }
151
152 // Otherwise, go ahead and enqueue the buffer. Must reaquire the lock.
153 _cbl_mon->lock_without_safepoint_check();
154 }
155
156 // Here we still hold the _cbl_mon.
157 CompletedBufferNode* cbn = new CompletedBufferNode;
158 cbn->buf = buf;
159 cbn->next = NULL;
160 cbn->index = index;
161 if (_completed_buffers_tail == NULL) {
162 assert(_completed_buffers_head == NULL, "Well-formedness");
163 _completed_buffers_head = cbn;
164 _completed_buffers_tail = cbn;
165 } else {
166 _completed_buffers_tail->next = cbn;
167 _completed_buffers_tail = cbn;
168 }
169 _n_completed_buffers++;
170
171 if (!_process_completed &&
172 _n_completed_buffers == _process_completed_threshold) {
173 _process_completed = true;
174 if (_notify_when_complete)
175 _cbl_mon->notify_all();
176 }
177 debug_only(assert_completed_buffer_list_len_correct_locked());
178 _cbl_mon->unlock();
179 }
180
181 int PtrQueueSet::completed_buffers_list_length() {
182 int n = 0;
183 CompletedBufferNode* cbn = _completed_buffers_head;
184 while (cbn != NULL) {
185 n++;
186 cbn = cbn->next;
187 }
188 return n;
189 }
190
191 void PtrQueueSet::assert_completed_buffer_list_len_correct() {
192 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
193 assert_completed_buffer_list_len_correct_locked();
194 }
195
196 void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() {
197 guarantee((size_t)completed_buffers_list_length() == _n_completed_buffers,
198 "Completed buffer length is wrong.");
199 }
200
201 void PtrQueueSet::set_buffer_size(size_t sz) {
202 assert(_sz == 0 && sz > 0, "Should be called only once.");
203 _sz = sz * oopSize;
204 }
205
206 void PtrQueueSet::set_process_completed_threshold(size_t sz) {
207 _process_completed_threshold = sz;
208 }