Thu, 07 Aug 2014 22:28:53 +0200
8054341: Remove some obsolete code in G1CollectedHeap class
Summary: Remove dead code.
Reviewed-by: stefank, brutisso
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 */
26 #include "precompiled.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"
29 #include "memory/iterator.hpp"
31 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
33 G1CodeRootChunk::G1CodeRootChunk() : _top(NULL), _next(NULL), _prev(NULL), _free(NULL) {
34 _top = bottom();
35 }
37 void G1CodeRootChunk::reset() {
38 _next = _prev = NULL;
39 _free = NULL;
40 _top = bottom();
41 }
43 void G1CodeRootChunk::nmethods_do(CodeBlobClosure* cl) {
44 NmethodOrLink* cur = bottom();
45 while (cur != _top) {
46 if (is_nmethod(cur)) {
47 cl->do_code_blob(cur->_nmethod);
48 }
49 cur++;
50 }
51 }
53 bool G1CodeRootChunk::remove_lock_free(nmethod* method) {
54 NmethodOrLink* cur = bottom();
56 for (NmethodOrLink* cur = bottom(); cur != _top; cur++) {
57 if (cur->_nmethod == method) {
58 bool result = Atomic::cmpxchg_ptr(NULL, &cur->_nmethod, method) == method;
60 if (!result) {
61 // Someone else cleared out this entry.
62 return false;
63 }
65 // The method was cleared. Time to link it into the free list.
66 NmethodOrLink* prev_free;
67 do {
68 prev_free = (NmethodOrLink*)_free;
69 cur->_link = prev_free;
70 } while (Atomic::cmpxchg_ptr(cur, &_free, prev_free) != prev_free);
72 return true;
73 }
74 }
76 return false;
77 }
79 G1CodeRootChunkManager::G1CodeRootChunkManager() : _free_list(), _num_chunks_handed_out(0) {
80 _free_list.initialize();
81 _free_list.set_size(G1CodeRootChunk::word_size());
82 }
84 size_t G1CodeRootChunkManager::fl_mem_size() {
85 return _free_list.count() * _free_list.size();
86 }
88 void G1CodeRootChunkManager::free_all_chunks(FreeList<G1CodeRootChunk>* list) {
89 _num_chunks_handed_out -= list->count();
90 _free_list.prepend(list);
91 }
93 void G1CodeRootChunkManager::free_chunk(G1CodeRootChunk* chunk) {
94 _free_list.return_chunk_at_head(chunk);
95 _num_chunks_handed_out--;
96 }
98 void G1CodeRootChunkManager::purge_chunks(size_t keep_ratio) {
99 size_t keep = _num_chunks_handed_out * keep_ratio / 100;
100 if (keep >= (size_t)_free_list.count()) {
101 return;
102 }
104 FreeList<G1CodeRootChunk> temp;
105 temp.initialize();
106 temp.set_size(G1CodeRootChunk::word_size());
108 _free_list.getFirstNChunksFromList((size_t)_free_list.count() - keep, &temp);
110 G1CodeRootChunk* cur = temp.get_chunk_at_head();
111 while (cur != NULL) {
112 delete cur;
113 cur = temp.get_chunk_at_head();
114 }
115 }
117 size_t G1CodeRootChunkManager::static_mem_size() {
118 return sizeof(G1CodeRootChunkManager);
119 }
122 G1CodeRootChunk* G1CodeRootChunkManager::new_chunk() {
123 G1CodeRootChunk* result = _free_list.get_chunk_at_head();
124 if (result == NULL) {
125 result = new G1CodeRootChunk();
126 }
127 _num_chunks_handed_out++;
128 result->reset();
129 return result;
130 }
132 #ifndef PRODUCT
134 size_t G1CodeRootChunkManager::num_chunks_handed_out() const {
135 return _num_chunks_handed_out;
136 }
138 size_t G1CodeRootChunkManager::num_free_chunks() const {
139 return (size_t)_free_list.count();
140 }
142 #endif
144 G1CodeRootChunkManager G1CodeRootSet::_default_chunk_manager;
146 void G1CodeRootSet::purge_chunks(size_t keep_ratio) {
147 _default_chunk_manager.purge_chunks(keep_ratio);
148 }
150 size_t G1CodeRootSet::free_chunks_static_mem_size() {
151 return _default_chunk_manager.static_mem_size();
152 }
154 size_t G1CodeRootSet::free_chunks_mem_size() {
155 return _default_chunk_manager.fl_mem_size();
156 }
158 G1CodeRootSet::G1CodeRootSet(G1CodeRootChunkManager* manager) : _manager(manager), _list(), _length(0) {
159 if (_manager == NULL) {
160 _manager = &_default_chunk_manager;
161 }
162 _list.initialize();
163 _list.set_size(G1CodeRootChunk::word_size());
164 }
166 G1CodeRootSet::~G1CodeRootSet() {
167 clear();
168 }
170 void G1CodeRootSet::add(nmethod* method) {
171 if (!contains(method)) {
172 // Find the first chunk that isn't full.
173 G1CodeRootChunk* cur = _list.head();
174 while (cur != NULL) {
175 if (!cur->is_full()) {
176 break;
177 }
178 cur = cur->next();
179 }
181 // All chunks are full, get a new chunk.
182 if (cur == NULL) {
183 cur = new_chunk();
184 _list.return_chunk_at_head(cur);
185 }
187 // Add the nmethod.
188 bool result = cur->add(method);
190 guarantee(result, err_msg("Not able to add nmethod "PTR_FORMAT" to newly allocated chunk.", method));
192 _length++;
193 }
194 }
196 void G1CodeRootSet::remove_lock_free(nmethod* method) {
197 G1CodeRootChunk* found = find(method);
198 if (found != NULL) {
199 bool result = found->remove_lock_free(method);
200 if (result) {
201 Atomic::dec_ptr((volatile intptr_t*)&_length);
202 }
203 }
204 assert(!contains(method), err_msg(PTR_FORMAT" still contains nmethod "PTR_FORMAT, this, method));
205 }
207 nmethod* G1CodeRootSet::pop() {
208 while (true) {
209 G1CodeRootChunk* cur = _list.head();
210 if (cur == NULL) {
211 assert(_length == 0, "when there are no chunks, there should be no elements");
212 return NULL;
213 }
214 nmethod* result = cur->pop();
215 if (result != NULL) {
216 _length--;
217 return result;
218 } else {
219 free(_list.get_chunk_at_head());
220 }
221 }
222 }
224 G1CodeRootChunk* G1CodeRootSet::find(nmethod* method) {
225 G1CodeRootChunk* cur = _list.head();
226 while (cur != NULL) {
227 if (cur->contains(method)) {
228 return cur;
229 }
230 cur = (G1CodeRootChunk*)cur->next();
231 }
232 return NULL;
233 }
235 void G1CodeRootSet::free(G1CodeRootChunk* chunk) {
236 free_chunk(chunk);
237 }
239 bool G1CodeRootSet::contains(nmethod* method) {
240 return find(method) != NULL;
241 }
243 void G1CodeRootSet::clear() {
244 free_all_chunks(&_list);
245 _length = 0;
246 }
248 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {
249 G1CodeRootChunk* cur = _list.head();
250 while (cur != NULL) {
251 cur->nmethods_do(blk);
252 cur = (G1CodeRootChunk*)cur->next();
253 }
254 }
256 size_t G1CodeRootSet::static_mem_size() {
257 return sizeof(G1CodeRootSet);
258 }
260 size_t G1CodeRootSet::mem_size() {
261 return G1CodeRootSet::static_mem_size() + _list.count() * _list.size();
262 }
264 #ifndef PRODUCT
266 void G1CodeRootSet::test() {
267 G1CodeRootChunkManager mgr;
269 assert(mgr.num_chunks_handed_out() == 0, "Must not have handed out chunks yet");
271 assert(G1CodeRootChunkManager::static_mem_size() > sizeof(void*),
272 err_msg("The chunk manager's static memory usage seems too small, is only "SIZE_FORMAT" bytes.", G1CodeRootChunkManager::static_mem_size()));
274 // The number of chunks that we allocate for purge testing.
275 size_t const num_chunks = 10;
277 {
278 G1CodeRootSet set1(&mgr);
279 assert(set1.is_empty(), "Code root set must be initially empty but is not.");
281 assert(G1CodeRootSet::static_mem_size() > sizeof(void*),
282 err_msg("The code root set's static memory usage seems too small, is only "SIZE_FORMAT" bytes", G1CodeRootSet::static_mem_size()));
284 set1.add((nmethod*)1);
285 assert(mgr.num_chunks_handed_out() == 1,
286 err_msg("Must have allocated and handed out one chunk, but handed out "
287 SIZE_FORMAT" chunks", mgr.num_chunks_handed_out()));
288 assert(set1.length() == 1, err_msg("Added exactly one element, but set contains "
289 SIZE_FORMAT" elements", set1.length()));
291 // G1CodeRootChunk::word_size() is larger than G1CodeRootChunk::num_entries which
292 // we cannot access.
293 for (uint i = 0; i < G1CodeRootChunk::word_size() + 1; i++) {
294 set1.add((nmethod*)1);
295 }
296 assert(mgr.num_chunks_handed_out() == 1,
297 err_msg("Duplicate detection must have prevented allocation of further "
298 "chunks but allocated "SIZE_FORMAT, mgr.num_chunks_handed_out()));
299 assert(set1.length() == 1,
300 err_msg("Duplicate detection should not have increased the set size but "
301 "is "SIZE_FORMAT, set1.length()));
303 size_t num_total_after_add = G1CodeRootChunk::word_size() + 1;
304 for (size_t i = 0; i < num_total_after_add - 1; i++) {
305 set1.add((nmethod*)(uintptr_t)(2 + i));
306 }
307 assert(mgr.num_chunks_handed_out() > 1,
308 "After adding more code roots, more than one additional chunk should have been handed out");
309 assert(set1.length() == num_total_after_add,
310 err_msg("After adding in total "SIZE_FORMAT" distinct code roots, they "
311 "need to be in the set, but there are only "SIZE_FORMAT,
312 num_total_after_add, set1.length()));
314 size_t num_popped = 0;
315 while (set1.pop() != NULL) {
316 num_popped++;
317 }
318 assert(num_popped == num_total_after_add,
319 err_msg("Managed to pop "SIZE_FORMAT" code roots, but only "SIZE_FORMAT" "
320 "were added", num_popped, num_total_after_add));
321 assert(mgr.num_chunks_handed_out() == 0,
322 err_msg("After popping all elements, all chunks must have been returned "
323 "but there are still "SIZE_FORMAT" additional", mgr.num_chunks_handed_out()));
325 mgr.purge_chunks(0);
326 assert(mgr.num_free_chunks() == 0,
327 err_msg("After purging everything, the free list must be empty but still "
328 "contains "SIZE_FORMAT" chunks", mgr.num_free_chunks()));
330 // Add some more handed out chunks.
331 size_t i = 0;
332 while (mgr.num_chunks_handed_out() < num_chunks) {
333 set1.add((nmethod*)i);
334 i++;
335 }
337 {
338 // Generate chunks on the free list.
339 G1CodeRootSet set2(&mgr);
340 size_t i = 0;
341 while (mgr.num_chunks_handed_out() < (num_chunks * 2)) {
342 set2.add((nmethod*)i);
343 i++;
344 }
345 // Exit of the scope of the set2 object will call the destructor that generates
346 // num_chunks elements on the free list.
347 }
349 assert(mgr.num_chunks_handed_out() == num_chunks,
350 err_msg("Deletion of the second set must have resulted in giving back "
351 "those, but there are still "SIZE_FORMAT" additional handed out, expecting "
352 SIZE_FORMAT, mgr.num_chunks_handed_out(), num_chunks));
353 assert(mgr.num_free_chunks() == num_chunks,
354 err_msg("After freeing "SIZE_FORMAT" chunks, they must be on the free list "
355 "but there are only "SIZE_FORMAT, num_chunks, mgr.num_free_chunks()));
357 size_t const test_percentage = 50;
358 mgr.purge_chunks(test_percentage);
359 assert(mgr.num_chunks_handed_out() == num_chunks,
360 err_msg("Purging must not hand out chunks but there are "SIZE_FORMAT,
361 mgr.num_chunks_handed_out()));
362 assert(mgr.num_free_chunks() == (size_t)(mgr.num_chunks_handed_out() * test_percentage / 100),
363 err_msg("Must have purged "SIZE_FORMAT" percent of "SIZE_FORMAT" chunks"
364 "but there are "SIZE_FORMAT, test_percentage, num_chunks,
365 mgr.num_free_chunks()));
366 // Purge the remainder of the chunks on the free list.
367 mgr.purge_chunks(0);
368 assert(mgr.num_free_chunks() == 0, "Free List must be empty");
369 assert(mgr.num_chunks_handed_out() == num_chunks,
370 err_msg("Expected to be "SIZE_FORMAT" chunks handed out from the first set "
371 "but there are "SIZE_FORMAT, num_chunks, mgr.num_chunks_handed_out()));
373 // Exit of the scope of the set1 object will call the destructor that generates
374 // num_chunks additional elements on the free list.
375 }
377 assert(mgr.num_chunks_handed_out() == 0,
378 err_msg("Deletion of the only set must have resulted in no chunks handed "
379 "out, but there is still "SIZE_FORMAT" handed out", mgr.num_chunks_handed_out()));
380 assert(mgr.num_free_chunks() == num_chunks,
381 err_msg("After freeing "SIZE_FORMAT" chunks, they must be on the free list "
382 "but there are only "SIZE_FORMAT, num_chunks, mgr.num_free_chunks()));
384 // Restore initial state.
385 mgr.purge_chunks(0);
386 assert(mgr.num_free_chunks() == 0, "Free List must be empty");
387 assert(mgr.num_chunks_handed_out() == 0, "No additional elements must have been handed out yet");
388 }
390 void TestCodeCacheRemSet_test() {
391 G1CodeRootSet::test();
392 }
393 #endif