1 /*
2 * Copyright (c) 2001, 2018, 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/ptrQueue.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "runtime/mutex.hpp"
30 #include "runtime/mutexLocker.hpp"
31 #include "runtime/thread.inline.hpp"
32
33 #include <new>
34
35 PtrQueue::PtrQueue(PtrQueueSet* qset, bool permanent, bool active) :
36 _qset(qset),
37 _active(active),
38 _permanent(permanent),
39 _index(0),
40 _capacity_in_bytes(0),
41 _buf(NULL),
42 _lock(NULL)
43 {}
44
45 PtrQueue::~PtrQueue() {
46 assert(_permanent || (_buf == NULL), "queue must be flushed before delete");
47 }
48
49 void PtrQueue::flush_impl() {
50 if (_buf != NULL) {
51 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index());
52 if (is_empty()) {
53 // No work to do.
54 qset()->deallocate_buffer(node);
55 } else {
56 qset()->enqueue_complete_buffer(node);
57 }
58 _buf = NULL;
59 set_index(0);
60 }
61 }
62
63
64 void PtrQueue::enqueue_known_active(void* ptr) {
65 while (_index == 0) {
66 handle_zero_index();
67 }
68
69 assert(_buf != NULL, "postcondition");
70 assert(index() > 0, "postcondition");
71 assert(index() <= capacity(), "invariant");
72 _index -= _element_size;
73 _buf[index()] = ptr;
74 }
75
76 void PtrQueue::locking_enqueue_completed_buffer(BufferNode* node) {
77 assert(_lock->owned_by_self(), "Required.");
78 qset()->enqueue_complete_buffer(node);
79 }
80
81
82 BufferNode* BufferNode::allocate(size_t size) {
83 size_t byte_size = size * sizeof(void*);
84 void* data = NEW_C_HEAP_ARRAY(char, buffer_offset() + byte_size, mtGC);
85 return new (data) BufferNode;
86 }
87
88 void BufferNode::deallocate(BufferNode* node) {
89 node->~BufferNode();
90 FREE_C_HEAP_ARRAY(char, node);
91 }
92
93 PtrQueueSet::PtrQueueSet(bool notify_when_complete) :
94 _buffer_size(0),
95 _cbl_mon(NULL),
96 _completed_buffers_head(NULL),
97 _completed_buffers_tail(NULL),
98 _n_completed_buffers(0),
99 _process_completed_threshold(0),
100 _process_completed(false),
101 _fl_lock(NULL),
102 _buf_free_list(NULL),
103 _buf_free_list_sz(0),
104 _fl_owner(NULL),
105 _all_active(false),
106 _notify_when_complete(notify_when_complete),
107 _max_completed_queue(0),
108 _completed_queue_padding(0)
109 {
110 _fl_owner = this;
111 }
112
113 PtrQueueSet::~PtrQueueSet() {
114 // There are presently only a couple (derived) instances ever
115 // created, and they are permanent, so no harm currently done by
116 // doing nothing here.
117 }
118
119 void PtrQueueSet::initialize(Monitor* cbl_mon,
120 Mutex* fl_lock,
121 int process_completed_threshold,
122 int max_completed_queue,
123 PtrQueueSet *fl_owner) {
124 _max_completed_queue = max_completed_queue;
125 _process_completed_threshold = process_completed_threshold;
126 _completed_queue_padding = 0;
127 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
128 _cbl_mon = cbl_mon;
129 _fl_lock = fl_lock;
130 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
131 }
132
133 void** PtrQueueSet::allocate_buffer() {
134 BufferNode* node = NULL;
135 {
136 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag);
137 node = _fl_owner->_buf_free_list;
138 if (node != NULL) {
139 _fl_owner->_buf_free_list = node->next();
140 _fl_owner->_buf_free_list_sz--;
141 }
142 }
143 if (node == NULL) {
144 node = BufferNode::allocate(buffer_size());
145 } else {
146 // Reinitialize buffer obtained from free list.
147 node->set_index(0);
148 node->set_next(NULL);
149 }
150 return BufferNode::make_buffer_from_node(node);
151 }
152
153 void PtrQueueSet::deallocate_buffer(BufferNode* node) {
154 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag);
155 node->set_next(_fl_owner->_buf_free_list);
156 _fl_owner->_buf_free_list = node;
157 _fl_owner->_buf_free_list_sz++;
158 }
159
160 void PtrQueueSet::reduce_free_list() {
161 assert(_fl_owner == this, "Free list reduction is allowed only for the owner");
162 // For now we'll adopt the strategy of deleting half.
163 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
164 size_t n = _buf_free_list_sz / 2;
165 for (size_t i = 0; i < n; ++i) {
166 assert(_buf_free_list != NULL,
167 "_buf_free_list_sz is wrong: " SIZE_FORMAT, _buf_free_list_sz);
168 BufferNode* node = _buf_free_list;
169 _buf_free_list = node->next();
170 _buf_free_list_sz--;
171 BufferNode::deallocate(node);
172 }
173 }
174
175 void PtrQueue::handle_zero_index() {
176 assert(index() == 0, "precondition");
177
178 // This thread records the full buffer and allocates a new one (while
179 // holding the lock if there is one).
180 if (_buf != NULL) {
181 if (!should_enqueue_buffer()) {
182 assert(index() > 0, "the buffer can only be re-used if it's not full");
183 return;
184 }
185
186 if (_lock) {
187 assert(_lock->owned_by_self(), "Required.");
188
189 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index());
190 _buf = NULL; // clear shared _buf field
191
192 locking_enqueue_completed_buffer(node); // enqueue completed buffer
193 assert(_buf == NULL, "multiple enqueuers appear to be racing");
194 } else {
195 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index());
196 if (qset()->process_or_enqueue_complete_buffer(node)) {
197 // Recycle the buffer. No allocation.
198 assert(_buf == BufferNode::make_buffer_from_node(node), "invariant");
199 assert(capacity() == qset()->buffer_size(), "invariant");
200 reset();
201 return;
202 }
203 }
204 }
205 // Set capacity in case this is the first allocation.
206 set_capacity(qset()->buffer_size());
207 // Allocate a new buffer.
208 _buf = qset()->allocate_buffer();
209 reset();
210 }
211
212 bool PtrQueueSet::process_or_enqueue_complete_buffer(BufferNode* node) {
213 if (Thread::current()->is_Java_thread()) {
214 // We don't lock. It is fine to be epsilon-precise here.
215 if (_max_completed_queue == 0 ||
216 (_max_completed_queue > 0 &&
217 _n_completed_buffers >= _max_completed_queue + _completed_queue_padding)) {
218 bool b = mut_process_buffer(node);
219 if (b) {
220 // True here means that the buffer hasn't been deallocated and the caller may reuse it.
221 return true;
222 }
223 }
224 }
225 // The buffer will be enqueued. The caller will have to get a new one.
226 enqueue_complete_buffer(node);
227 return false;
228 }
229
230 void PtrQueueSet::enqueue_complete_buffer(BufferNode* cbn) {
231 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
232 cbn->set_next(NULL);
233 if (_completed_buffers_tail == NULL) {
234 assert(_completed_buffers_head == NULL, "Well-formedness");
235 _completed_buffers_head = cbn;
236 _completed_buffers_tail = cbn;
237 } else {
238 _completed_buffers_tail->set_next(cbn);
239 _completed_buffers_tail = cbn;
240 }
241 _n_completed_buffers++;
242
243 if (!_process_completed && _process_completed_threshold >= 0 &&
244 _n_completed_buffers >= (size_t)_process_completed_threshold) {
245 _process_completed = true;
246 if (_notify_when_complete) {
247 _cbl_mon->notify();
248 }
249 }
250 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
251 }
252
253 size_t PtrQueueSet::completed_buffers_list_length() {
254 size_t n = 0;
255 BufferNode* cbn = _completed_buffers_head;
256 while (cbn != NULL) {
257 n++;
258 cbn = cbn->next();
259 }
260 return n;
261 }
262
263 void PtrQueueSet::assert_completed_buffer_list_len_correct() {
264 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
265 assert_completed_buffer_list_len_correct_locked();
266 }
267
268 void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() {
269 guarantee(completed_buffers_list_length() == _n_completed_buffers,
270 "Completed buffer length is wrong.");
271 }
272
273 void PtrQueueSet::set_buffer_size(size_t sz) {
274 assert(_buffer_size == 0 && sz > 0, "Should be called only once.");
275 _buffer_size = sz;
276 }
277
278 // Merge lists of buffers. Notify the processing threads.
279 // The source queue is emptied as a result. The queues
280 // must share the monitor.
281 void PtrQueueSet::merge_bufferlists(PtrQueueSet *src) {
282 assert(_cbl_mon == src->_cbl_mon, "Should share the same lock");
283 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
284 if (_completed_buffers_tail == NULL) {
285 assert(_completed_buffers_head == NULL, "Well-formedness");
286 _completed_buffers_head = src->_completed_buffers_head;
287 _completed_buffers_tail = src->_completed_buffers_tail;
288 } else {
289 assert(_completed_buffers_head != NULL, "Well formedness");
290 if (src->_completed_buffers_head != NULL) {
291 _completed_buffers_tail->set_next(src->_completed_buffers_head);
292 _completed_buffers_tail = src->_completed_buffers_tail;
293 }
294 }
295 _n_completed_buffers += src->_n_completed_buffers;
296
297 src->_n_completed_buffers = 0;
298 src->_completed_buffers_head = NULL;
299 src->_completed_buffers_tail = NULL;
300
301 assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL ||
302 _completed_buffers_head != NULL && _completed_buffers_tail != NULL,
303 "Sanity");
304 }
305
306 void PtrQueueSet::notify_if_necessary() {
307 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
308 assert(_process_completed_threshold >= 0, "_process_completed is negative");
309 if (_n_completed_buffers >= (size_t)_process_completed_threshold || _max_completed_queue == 0) {
310 _process_completed = true;
311 if (_notify_when_complete)
312 _cbl_mon->notify();
313 }
314 }