1 /*
2 * Copyright (c) 2001, 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 "memory/freeBlockDictionary.hpp"
27 #include "memory/freeList.hpp"
28 #include "memory/metachunk.hpp"
29 #include "memory/sharedHeap.hpp"
30 #include "runtime/globals.hpp"
31 #include "runtime/mutex.hpp"
32 #include "runtime/vmThread.hpp"
33 #include "utilities/macros.hpp"
34
35 #if INCLUDE_ALL_GCS
36 #include "gc_implementation/concurrentMarkSweep/freeChunk.hpp"
37 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"
38 #endif // INCLUDE_ALL_GCS
39
40 // Free list. A FreeList is used to access a linked list of chunks
41 // of space in the heap. The head and tail are maintained so that
42 // items can be (as in the current implementation) added at the
43 // at the tail of the list and removed from the head of the list to
44 // maintain a FIFO queue.
45
46 template <class Chunk>
47 FreeList<Chunk>::FreeList() :
48 _head(NULL), _tail(NULL)
49 #ifdef ASSERT
50 , _protecting_lock(NULL)
51 #endif
52 {
53 _size = 0;
54 _count = 0;
55 }
56
57 template <class Chunk>
58 void FreeList<Chunk>::link_head(Chunk* v) {
59 assert_proper_lock_protection();
60 set_head(v);
61 // If this method is not used (just set the head instead),
62 // this check can be avoided.
63 if (v != NULL) {
64 v->link_prev(NULL);
65 }
66 }
67
68
69
70 template <class Chunk>
71 void FreeList<Chunk>::reset() {
72 // Don't set the _size to 0 because this method is
73 // used with a existing list that has a size but which has
74 // been emptied.
75 // Don't clear the _protecting_lock of an existing list.
76 set_count(0);
77 set_head(NULL);
78 set_tail(NULL);
79 }
80
81 template <class Chunk>
82 void FreeList<Chunk>::initialize() {
83 #ifdef ASSERT
84 // Needed early because it might be checked in other initializing code.
85 set_protecting_lock(NULL);
86 #endif
87 reset();
88 set_size(0);
89 }
90
91 template <class Chunk_t>
92 Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() {
93 assert_proper_lock_protection();
94 assert(head() == NULL || head()->prev() == NULL, "list invariant");
95 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
96 Chunk_t* fc = head();
97 if (fc != NULL) {
98 Chunk_t* nextFC = fc->next();
99 if (nextFC != NULL) {
100 // The chunk fc being removed has a "next". Set the "next" to the
101 // "prev" of fc.
102 nextFC->link_prev(NULL);
103 } else { // removed tail of list
104 link_tail(NULL);
105 }
106 link_head(nextFC);
107 decrement_count();
108 }
109 assert(head() == NULL || head()->prev() == NULL, "list invariant");
110 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
111 return fc;
112 }
113
114
115 template <class Chunk>
116 void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) {
117 assert_proper_lock_protection();
118 assert(fl->count() == 0, "Precondition");
119 if (count() > 0) {
120 int k = 1;
121 fl->set_head(head()); n--;
122 Chunk* tl = head();
123 while (tl->next() != NULL && n > 0) {
124 tl = tl->next(); n--; k++;
125 }
126 assert(tl != NULL, "Loop Inv.");
127
128 // First, fix up the list we took from.
129 Chunk* new_head = tl->next();
130 set_head(new_head);
131 set_count(count() - k);
132 if (new_head == NULL) {
133 set_tail(NULL);
134 } else {
135 new_head->link_prev(NULL);
136 }
137 // Now we can fix up the tail.
138 tl->link_next(NULL);
139 // And return the result.
140 fl->set_tail(tl);
141 fl->set_count(k);
142 }
143 }
144
145 // Remove this chunk from the list
146 template <class Chunk>
147 void FreeList<Chunk>::remove_chunk(Chunk*fc) {
148 assert_proper_lock_protection();
149 assert(head() != NULL, "Remove from empty list");
150 assert(fc != NULL, "Remove a NULL chunk");
151 assert(size() == fc->size(), "Wrong list");
152 assert(head() == NULL || head()->prev() == NULL, "list invariant");
153 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
154
155 Chunk* prevFC = fc->prev();
156 Chunk* nextFC = fc->next();
157 if (nextFC != NULL) {
158 // The chunk fc being removed has a "next". Set the "next" to the
159 // "prev" of fc.
160 nextFC->link_prev(prevFC);
161 } else { // removed tail of list
162 link_tail(prevFC);
163 }
164 if (prevFC == NULL) { // removed head of list
165 link_head(nextFC);
166 assert(nextFC == NULL || nextFC->prev() == NULL,
167 "Prev of head should be NULL");
168 } else {
169 prevFC->link_next(nextFC);
170 assert(tail() != prevFC || prevFC->next() == NULL,
171 "Next of tail should be NULL");
172 }
173 decrement_count();
174 assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0,
175 "H/T/C Inconsistency");
176 // clear next and prev fields of fc, debug only
177 NOT_PRODUCT(
178 fc->link_prev(NULL);
179 fc->link_next(NULL);
180 )
181 assert(fc->is_free(), "Should still be a free chunk");
182 assert(head() == NULL || head()->prev() == NULL, "list invariant");
183 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
184 assert(head() == NULL || head()->size() == size(), "wrong item on list");
185 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
186 }
187
188 // Add this chunk at the head of the list.
189 template <class Chunk>
190 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk, bool record_return) {
191 assert_proper_lock_protection();
192 assert(chunk != NULL, "insert a NULL chunk");
193 assert(size() == chunk->size(), "Wrong size");
194 assert(head() == NULL || head()->prev() == NULL, "list invariant");
195 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
196
197 Chunk* oldHead = head();
198 assert(chunk != oldHead, "double insertion");
199 chunk->link_after(oldHead);
200 link_head(chunk);
201 if (oldHead == NULL) { // only chunk in list
202 assert(tail() == NULL, "inconsistent FreeList");
203 link_tail(chunk);
204 }
205 increment_count(); // of # of chunks in list
206 assert(head() == NULL || head()->prev() == NULL, "list invariant");
207 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
208 assert(head() == NULL || head()->size() == size(), "wrong item on list");
209 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
210 }
211
212 template <class Chunk>
213 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) {
214 assert_proper_lock_protection();
215 return_chunk_at_head(chunk, true);
216 }
217
218 // Add this chunk at the tail of the list.
219 template <class Chunk>
220 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk, bool record_return) {
221 assert_proper_lock_protection();
222 assert(head() == NULL || head()->prev() == NULL, "list invariant");
223 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
224 assert(chunk != NULL, "insert a NULL chunk");
225 assert(size() == chunk->size(), "wrong size");
226
227 Chunk* oldTail = tail();
228 assert(chunk != oldTail, "double insertion");
229 if (oldTail != NULL) {
230 oldTail->link_after(chunk);
231 } else { // only chunk in list
232 assert(head() == NULL, "inconsistent FreeList");
233 link_head(chunk);
234 }
235 link_tail(chunk);
236 increment_count(); // of # of chunks in list
237 assert(head() == NULL || head()->prev() == NULL, "list invariant");
238 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
239 assert(head() == NULL || head()->size() == size(), "wrong item on list");
240 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
241 }
242
243 template <class Chunk>
244 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) {
245 return_chunk_at_tail(chunk, true);
246 }
247
248 template <class Chunk>
249 void FreeList<Chunk>::prepend(FreeList<Chunk>* fl) {
250 assert_proper_lock_protection();
251 if (fl->count() > 0) {
252 if (count() == 0) {
253 set_head(fl->head());
254 set_tail(fl->tail());
255 set_count(fl->count());
256 } else {
257 // Both are non-empty.
258 Chunk* fl_tail = fl->tail();
259 Chunk* this_head = head();
260 assert(fl_tail->next() == NULL, "Well-formedness of fl");
261 fl_tail->link_next(this_head);
262 this_head->link_prev(fl_tail);
263 set_head(fl->head());
264 set_count(count() + fl->count());
265 }
266 fl->set_head(NULL);
267 fl->set_tail(NULL);
268 fl->set_count(0);
269 }
270 }
271
272 // verify_chunk_in_free_lists() is used to verify that an item is in this free list.
273 // It is used as a debugging aid.
274 template <class Chunk>
275 bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* fc) const {
276 // This is an internal consistency check, not part of the check that the
277 // chunk is in the free lists.
278 guarantee(fc->size() == size(), "Wrong list is being searched");
279 Chunk* curFC = head();
280 while (curFC) {
281 // This is an internal consistency check.
282 guarantee(size() == curFC->size(), "Chunk is in wrong list.");
283 if (fc == curFC) {
284 return true;
285 }
286 curFC = curFC->next();
287 }
288 return false;
289 }
290
291 #ifndef PRODUCT
292 template <class Chunk>
293 void FreeList<Chunk>::assert_proper_lock_protection_work() const {
294 assert(protecting_lock() != NULL, "Don't call this directly");
295 assert(ParallelGCThreads > 0, "Don't call this directly");
296 Thread* thr = Thread::current();
297 if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) {
298 // assert that we are holding the freelist lock
299 } else if (thr->is_GC_task_thread()) {
300 assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED");
301 } else if (thr->is_Java_thread()) {
302 assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing");
303 } else {
304 ShouldNotReachHere(); // unaccounted thread type?
305 }
306 }
307 #endif
308
309 // Print the "label line" for free list stats.
310 template <class Chunk>
311 void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) {
312 st->print("%16s\t", c);
313 st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t"
314 "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n",
315 "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep",
316 "count", "cBirths", "cDeaths", "sBirths", "sDeaths");
317 }
318
319 // Print the AllocationStats for the given free list. If the second argument
320 // to the call is a non-null string, it is printed in the first column;
321 // otherwise, if the argument is null (the default), then the size of the
322 // (free list) block is printed in the first column.
323 template <class Chunk_t>
324 void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const {
325 if (c != NULL) {
326 st->print("%16s", c);
327 } else {
328 st->print(SIZE_FORMAT_W(16), size());
329 }
330 }
331
332 template class FreeList<Metablock>;
333 template class FreeList<Metachunk>;
334 #if INCLUDE_ALL_GCS
335 template class FreeList<FreeChunk>;
336 template class FreeList<G1CodeRootChunk>;
337 #endif // INCLUDE_ALL_GCS