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.
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23 */
24
25 #ifndef SHARE_MEMORY_FREELIST_INLINE_HPP
26 #define SHARE_MEMORY_FREELIST_INLINE_HPP
27
28 #include "gc/shared/collectedHeap.hpp"
29 #include "memory/freeList.hpp"
30 #include "memory/metachunk.hpp"
31 #include "runtime/globals.hpp"
32 #include "runtime/mutex.hpp"
33 #include "runtime/vmThread.hpp"
34 #include "utilities/macros.hpp"
35
36 // Free list. A FreeList is used to access a linked list of chunks
37 // of space in the heap. The head and tail are maintained so that
38 // items can be (as in the current implementation) added at the
39 // at the tail of the list and removed from the head of the list to
40 // maintain a FIFO queue.
41
42 template <class Chunk>
43 FreeList<Chunk>::FreeList() :
44 _head(NULL), _tail(NULL)
45 #ifdef ASSERT
46 , _protecting_lock(NULL)
47 #endif
48 {
49 _size = 0;
50 _count = 0;
51 }
52
53 template <class Chunk>
54 void FreeList<Chunk>::link_head(Chunk* v) {
55 assert_proper_lock_protection();
56 set_head(v);
57 // If this method is not used (just set the head instead),
58 // this check can be avoided.
59 if (v != NULL) {
60 v->link_prev(NULL);
61 }
62 }
63
64
65
66 template <class Chunk>
67 void FreeList<Chunk>::reset() {
68 // Don't set the _size to 0 because this method is
69 // used with a existing list that has a size but which has
70 // been emptied.
71 // Don't clear the _protecting_lock of an existing list.
72 set_count(0);
73 set_head(NULL);
74 set_tail(NULL);
75 }
76
77 template <class Chunk>
78 void FreeList<Chunk>::initialize() {
79 #ifdef ASSERT
80 // Needed early because it might be checked in other initializing code.
81 set_protecting_lock(NULL);
82 #endif
83 reset();
84 set_size(0);
85 }
86
87 template <class Chunk_t>
88 Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() {
89 assert_proper_lock_protection();
90 assert(head() == NULL || head()->prev() == NULL, "list invariant");
91 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
92 Chunk_t* fc = head();
93 if (fc != NULL) {
94 Chunk_t* nextFC = fc->next();
95 if (nextFC != NULL) {
96 // The chunk fc being removed has a "next". Set the "next" to the
97 // "prev" of fc.
98 nextFC->link_prev(NULL);
99 } else { // removed tail of list
100 link_tail(NULL);
101 }
102 link_head(nextFC);
103 decrement_count();
104 }
105 assert(head() == NULL || head()->prev() == NULL, "list invariant");
106 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
107 return fc;
108 }
109
110
111 template <class Chunk>
112 void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) {
113 assert_proper_lock_protection();
114 assert(fl->count() == 0, "Precondition");
115 if (count() > 0) {
116 int k = 1;
117 fl->set_head(head()); n--;
118 Chunk* tl = head();
119 while (tl->next() != NULL && n > 0) {
120 tl = tl->next(); n--; k++;
121 }
122 assert(tl != NULL, "Loop Inv.");
123
124 // First, fix up the list we took from.
125 Chunk* new_head = tl->next();
126 set_head(new_head);
127 set_count(count() - k);
128 if (new_head == NULL) {
129 set_tail(NULL);
130 } else {
131 new_head->link_prev(NULL);
132 }
133 // Now we can fix up the tail.
134 tl->link_next(NULL);
135 // And return the result.
136 fl->set_tail(tl);
137 fl->set_count(k);
138 }
139 }
140
141 // Remove this chunk from the list
142 template <class Chunk>
143 void FreeList<Chunk>::remove_chunk(Chunk*fc) {
144 assert_proper_lock_protection();
145 assert(head() != NULL, "Remove from empty list");
146 assert(fc != NULL, "Remove a NULL chunk");
147 assert(size() == fc->size(), "Wrong list");
148 assert(head() == NULL || head()->prev() == NULL, "list invariant");
149 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
150
151 Chunk* prevFC = fc->prev();
152 Chunk* nextFC = fc->next();
153 if (nextFC != NULL) {
154 // The chunk fc being removed has a "next". Set the "next" to the
155 // "prev" of fc.
156 nextFC->link_prev(prevFC);
157 } else { // removed tail of list
158 link_tail(prevFC);
159 }
160 if (prevFC == NULL) { // removed head of list
161 link_head(nextFC);
162 assert(nextFC == NULL || nextFC->prev() == NULL,
163 "Prev of head should be NULL");
164 } else {
165 prevFC->link_next(nextFC);
166 assert(tail() != prevFC || prevFC->next() == NULL,
167 "Next of tail should be NULL");
168 }
169 decrement_count();
170 assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0,
171 "H/T/C Inconsistency");
172 // clear next and prev fields of fc, debug only
173 NOT_PRODUCT(
174 fc->link_prev(NULL);
175 fc->link_next(NULL);
176 )
177 assert(fc->is_free(), "Should still be a free chunk");
178 assert(head() == NULL || head()->prev() == NULL, "list invariant");
179 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
180 assert(head() == NULL || head()->size() == size(), "wrong item on list");
181 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
182 }
183
184 // Add this chunk at the head of the list.
185 template <class Chunk>
186 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk, bool record_return) {
187 assert_proper_lock_protection();
188 assert(chunk != NULL, "insert a NULL chunk");
189 assert(size() == chunk->size(), "Wrong size");
190 assert(head() == NULL || head()->prev() == NULL, "list invariant");
191 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
192
193 Chunk* oldHead = head();
194 assert(chunk != oldHead, "double insertion");
195 chunk->link_after(oldHead);
196 link_head(chunk);
197 if (oldHead == NULL) { // only chunk in list
198 assert(tail() == NULL, "inconsistent FreeList");
199 link_tail(chunk);
200 }
201 increment_count(); // of # of chunks in list
202 assert(head() == NULL || head()->prev() == NULL, "list invariant");
203 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
204 assert(head() == NULL || head()->size() == size(), "wrong item on list");
205 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
206 }
207
208 template <class Chunk>
209 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) {
210 assert_proper_lock_protection();
211 return_chunk_at_head(chunk, true);
212 }
213
214 // Add this chunk at the tail of the list.
215 template <class Chunk>
216 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk, bool record_return) {
217 assert_proper_lock_protection();
218 assert(head() == NULL || head()->prev() == NULL, "list invariant");
219 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
220 assert(chunk != NULL, "insert a NULL chunk");
221 assert(size() == chunk->size(), "wrong size");
222
223 Chunk* oldTail = tail();
224 assert(chunk != oldTail, "double insertion");
225 if (oldTail != NULL) {
226 oldTail->link_after(chunk);
227 } else { // only chunk in list
228 assert(head() == NULL, "inconsistent FreeList");
229 link_head(chunk);
230 }
231 link_tail(chunk);
232 increment_count(); // of # of chunks in list
233 assert(head() == NULL || head()->prev() == NULL, "list invariant");
234 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
235 assert(head() == NULL || head()->size() == size(), "wrong item on list");
236 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
237 }
238
239 template <class Chunk>
240 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) {
241 return_chunk_at_tail(chunk, true);
242 }
243
244 template <class Chunk>
245 void FreeList<Chunk>::prepend(FreeList<Chunk>* fl) {
246 assert_proper_lock_protection();
247 if (fl->count() > 0) {
248 if (count() == 0) {
249 set_head(fl->head());
250 set_tail(fl->tail());
251 set_count(fl->count());
252 } else {
253 // Both are non-empty.
254 Chunk* fl_tail = fl->tail();
255 Chunk* this_head = head();
256 assert(fl_tail->next() == NULL, "Well-formedness of fl");
257 fl_tail->link_next(this_head);
258 this_head->link_prev(fl_tail);
259 set_head(fl->head());
260 set_count(count() + fl->count());
261 }
262 fl->set_head(NULL);
263 fl->set_tail(NULL);
264 fl->set_count(0);
265 }
266 }
267
268 // verify_chunk_in_free_lists() is used to verify that an item is in this free list.
269 // It is used as a debugging aid.
270 template <class Chunk>
271 bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* fc) const {
272 // This is an internal consistency check, not part of the check that the
273 // chunk is in the free lists.
274 guarantee(fc->size() == size(), "Wrong list is being searched");
275 Chunk* curFC = head();
276 while (curFC) {
277 // This is an internal consistency check.
278 guarantee(size() == curFC->size(), "Chunk is in wrong list.");
279 if (fc == curFC) {
280 return true;
281 }
282 curFC = curFC->next();
283 }
284 return false;
285 }
286
287 #ifdef ASSERT
288 template <class Chunk>
289 void FreeList<Chunk>::assert_proper_lock_protection_work() const {
290 // Nothing to do if the list has no assigned protecting lock
291 if (protecting_lock() == NULL) {
292 return;
293 }
294
295 Thread* thr = Thread::current();
296 if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) {
297 // assert that we are holding the freelist lock
298 } else if (thr->is_GC_task_thread()) {
299 assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED");
300 } else if (thr->is_Java_thread()) {
301 assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing");
302 } else {
303 ShouldNotReachHere(); // unaccounted thread type?
304 }
305 }
306 #endif
307
308 // Print the "label line" for free list stats.
309 template <class Chunk>
310 void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) {
311 st->print("%16s\t", c);
312 st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t"
313 "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n",
314 "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep",
315 "count", "cBirths", "cDeaths", "sBirths", "sDeaths");
316 }
317
318 // Print the AllocationStats for the given free list. If the second argument
319 // to the call is a non-null string, it is printed in the first column;
320 // otherwise, if the argument is null (the default), then the size of the
321 // (free list) block is printed in the first column.
322 template <class Chunk_t>
323 void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const {
324 if (c != NULL) {
325 st->print("%16s", c);
326 } else {
327 st->print(SIZE_FORMAT_W(16), size());
328 }
329 }
330
331 #endif // SHARE_MEMORY_FREELIST_INLINE_HPP