1 /*
2 * Copyright (c) 2001, 2017, 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/g1/dirtyCardQueue.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1RemSet.hpp"
29 #include "gc/g1/heapRegionRemSet.hpp"
30 #include "gc/shared/workgroup.hpp"
31 #include "runtime/atomic.hpp"
32 #include "runtime/mutexLocker.hpp"
33 #include "runtime/safepoint.hpp"
34 #include "runtime/thread.inline.hpp"
35
36 // Closure used for updating remembered sets and recording references that
37 // point into the collection set while the mutator is running.
38 // Assumed to be only executed concurrently with the mutator. Yields via
39 // SuspendibleThreadSet after every card.
40 class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure {
41 public:
42 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
43 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
44
45 if (SuspendibleThreadSet::should_yield()) {
46 // Caller will actually yield.
47 return false;
48 }
49 // Otherwise, we finished successfully; return true.
50 return true;
51 }
52 };
53
54 // Represents a set of free small integer ids.
55 class FreeIdSet : public CHeapObj<mtGC> {
56 enum {
57 end_of_list = UINT_MAX,
58 claimed = UINT_MAX - 1
59 };
60
61 uint _size;
62 Monitor* _mon;
63
64 uint* _ids;
65 uint _hd;
66 uint _waiters;
67 uint _claimed;
68
69 public:
70 FreeIdSet(uint size, Monitor* mon);
71 ~FreeIdSet();
72
73 // Returns an unclaimed parallel id (waiting for one to be released if
74 // necessary).
75 uint claim_par_id();
76
77 void release_par_id(uint id);
78 };
79
80 FreeIdSet::FreeIdSet(uint size, Monitor* mon) :
81 _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)
82 {
83 guarantee(size != 0, "must be");
84 _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);
85 for (uint i = 0; i < size - 1; i++) {
86 _ids[i] = i+1;
87 }
88 _ids[size-1] = end_of_list; // end of list.
89 }
90
91 FreeIdSet::~FreeIdSet() {
92 FREE_C_HEAP_ARRAY(uint, _ids);
93 }
94
95 uint FreeIdSet::claim_par_id() {
96 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
97 while (_hd == end_of_list) {
98 _waiters++;
99 _mon->wait(Mutex::_no_safepoint_check_flag);
100 _waiters--;
101 }
102 uint res = _hd;
103 _hd = _ids[res];
104 _ids[res] = claimed; // For debugging.
105 _claimed++;
106 return res;
107 }
108
109 void FreeIdSet::release_par_id(uint id) {
110 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
111 assert(_ids[id] == claimed, "Precondition.");
112 _ids[id] = _hd;
113 _hd = id;
114 _claimed--;
115 if (_waiters > 0) {
116 _mon->notify_all();
117 }
118 }
119
120 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :
121 // Dirty card queues are always active, so we create them with their
122 // active field set to true.
123 PtrQueue(qset, permanent, true /* active */)
124 { }
125
126 DirtyCardQueue::~DirtyCardQueue() {
127 if (!is_permanent()) {
128 flush();
129 }
130 }
131
132 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :
133 PtrQueueSet(notify_when_complete),
134 _shared_dirty_card_queue(this, true /* permanent */),
135 _free_ids(NULL),
136 _processed_buffers_mut(0), _processed_buffers_rs_thread(0)
137 {
138 _all_active = true;
139 }
140
141 // Determines how many mutator threads can process the buffers in parallel.
142 uint DirtyCardQueueSet::num_par_ids() {
143 return (uint)os::initial_active_processor_count();
144 }
145
146 void DirtyCardQueueSet::initialize(Monitor* cbl_mon,
147 Mutex* fl_lock,
148 int process_completed_threshold,
149 int max_completed_queue,
150 Mutex* lock,
151 DirtyCardQueueSet* fl_owner,
152 bool init_free_ids) {
153 PtrQueueSet::initialize(cbl_mon,
154 fl_lock,
155 process_completed_threshold,
156 max_completed_queue,
157 fl_owner);
158 set_buffer_size(G1UpdateBufferSize);
159 _shared_dirty_card_queue.set_lock(lock);
160 if (init_free_ids) {
161 _free_ids = new FreeIdSet(num_par_ids(), _cbl_mon);
162 }
163 }
164
165 void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {
166 t->dirty_card_queue().handle_zero_index();
167 }
168
169 bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,
170 BufferNode* node,
171 bool consume,
172 uint worker_i) {
173 if (cl == NULL) return true;
174 bool result = true;
175 void** buf = BufferNode::make_buffer_from_node(node);
176 size_t i = node->index();
177 size_t limit = buffer_size();
178 for ( ; i < limit; ++i) {
179 jbyte* card_ptr = static_cast<jbyte*>(buf[i]);
180 assert(card_ptr != NULL, "invariant");
181 if (!cl->do_card_ptr(card_ptr, worker_i)) {
182 result = false; // Incomplete processing.
183 break;
184 }
185 }
186 if (consume) {
187 assert(i <= buffer_size(), "invariant");
188 node->set_index(i);
189 }
190 return result;
191 }
192
193 #ifndef ASSERT
194 #define assert_fully_consumed(node, buffer_size)
195 #else
196 #define assert_fully_consumed(node, buffer_size) \
197 do { \
198 size_t _afc_index = (node)->index(); \
199 size_t _afc_size = (buffer_size); \
200 assert(_afc_index == _afc_size, \
201 "Buffer was not fully consumed as claimed: index: " \
202 SIZE_FORMAT ", size: " SIZE_FORMAT, \
203 _afc_index, _afc_size); \
204 } while (0)
205 #endif // ASSERT
206
207 bool DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
208 guarantee(_free_ids != NULL, "must be");
209
210 uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
211 G1RefineCardConcurrentlyClosure cl;
212 bool result = apply_closure_to_buffer(&cl, node, true, worker_i);
213 _free_ids->release_par_id(worker_i); // release the id
214
215 if (result) {
216 assert_fully_consumed(node, buffer_size());
217 Atomic::inc(&_processed_buffers_mut);
218 }
219 return result;
220 }
221
222
223 BufferNode* DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {
224 BufferNode* nd = NULL;
225 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
226
227 if (_n_completed_buffers <= stop_at) {
228 _process_completed = false;
229 return NULL;
230 }
231
232 if (_completed_buffers_head != NULL) {
233 nd = _completed_buffers_head;
234 assert(_n_completed_buffers > 0, "Invariant");
235 _completed_buffers_head = nd->next();
236 _n_completed_buffers--;
237 if (_completed_buffers_head == NULL) {
238 assert(_n_completed_buffers == 0, "Invariant");
239 _completed_buffers_tail = NULL;
240 }
241 }
242 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
243 return nd;
244 }
245
246 bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {
247 G1RefineCardConcurrentlyClosure cl;
248 return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);
249 }
250
251 bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) {
252 assert_at_safepoint(false);
253 return apply_closure_to_completed_buffer(cl, worker_i, 0, true);
254 }
255
256 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
257 uint worker_i,
258 size_t stop_at,
259 bool during_pause) {
260 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
261 BufferNode* nd = get_completed_buffer(stop_at);
262 if (nd == NULL) {
263 return false;
264 } else {
265 if (apply_closure_to_buffer(cl, nd, true, worker_i)) {
266 assert_fully_consumed(nd, buffer_size());
267 // Done with fully processed buffer.
268 deallocate_buffer(nd);
269 Atomic::inc(&_processed_buffers_rs_thread);
270 } else {
271 // Return partially processed buffer to the queue.
272 guarantee(!during_pause, "Should never stop early");
273 enqueue_complete_buffer(nd);
274 }
275 return true;
276 }
277 }
278
279 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {
280 BufferNode* nd = _cur_par_buffer_node;
281 while (nd != NULL) {
282 BufferNode* next = nd->next();
283 BufferNode* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd);
284 if (actual == nd) {
285 bool b = apply_closure_to_buffer(cl, nd, false);
286 guarantee(b, "Should not stop early.");
287 nd = next;
288 } else {
289 nd = actual;
290 }
291 }
292 }
293
294 // Deallocates any completed log buffers
295 void DirtyCardQueueSet::clear() {
296 BufferNode* buffers_to_delete = NULL;
297 {
298 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
299 while (_completed_buffers_head != NULL) {
300 BufferNode* nd = _completed_buffers_head;
301 _completed_buffers_head = nd->next();
302 nd->set_next(buffers_to_delete);
303 buffers_to_delete = nd;
304 }
305 _n_completed_buffers = 0;
306 _completed_buffers_tail = NULL;
307 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
308 }
309 while (buffers_to_delete != NULL) {
310 BufferNode* nd = buffers_to_delete;
311 buffers_to_delete = nd->next();
312 deallocate_buffer(nd);
313 }
314
315 }
316
317 void DirtyCardQueueSet::abandon_logs() {
318 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
319 clear();
320 // Since abandon is done only at safepoints, we can safely manipulate
321 // these queues.
322 for (JavaThread* t = Threads::first(); t; t = t->next()) {
323 t->dirty_card_queue().reset();
324 }
325 shared_dirty_card_queue()->reset();
326 }
327
328 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {
329 if (!dcq.is_empty()) {
330 dcq.flush();
331 }
332 }
333
334 void DirtyCardQueueSet::concatenate_logs() {
335 // Iterate over all the threads, if we find a partial log add it to
336 // the global list of logs. Temporarily turn off the limit on the number
337 // of outstanding buffers.
338 int save_max_completed_queue = _max_completed_queue;
339 _max_completed_queue = max_jint;
340 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
341 for (JavaThread* t = Threads::first(); t; t = t->next()) {
342 concatenate_log(t->dirty_card_queue());
343 }
344 concatenate_log(_shared_dirty_card_queue);
345 // Restore the completed buffer queue limit.
346 _max_completed_queue = save_max_completed_queue;
347 }