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comparison src/share/vm/gc_implementation/concurrentMarkSweep/freeList.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2001-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_freeList.cpp.incl"
27
28 // Free list. A FreeList is used to access a linked list of chunks
29 // of space in the heap. The head and tail are maintained so that
30 // items can be (as in the current implementation) added at the
31 // at the tail of the list and removed from the head of the list to
32 // maintain a FIFO queue.
33
34 FreeList::FreeList() :
35 _head(NULL), _tail(NULL)
36 #ifdef ASSERT
37 , _protecting_lock(NULL)
38 #endif
39 {
40 _size = 0;
41 _count = 0;
42 _hint = 0;
43 init_statistics();
44 }
45
46 FreeList::FreeList(FreeChunk* fc) :
47 _head(fc), _tail(fc)
48 #ifdef ASSERT
49 , _protecting_lock(NULL)
50 #endif
51 {
52 _size = fc->size();
53 _count = 1;
54 _hint = 0;
55 init_statistics();
56 #ifndef PRODUCT
57 _allocation_stats.set_returnedBytes(size() * HeapWordSize);
58 #endif
59 }
60
61 FreeList::FreeList(HeapWord* addr, size_t size) :
62 _head((FreeChunk*) addr), _tail((FreeChunk*) addr)
63 #ifdef ASSERT
64 , _protecting_lock(NULL)
65 #endif
66 {
67 assert(size > sizeof(FreeChunk), "size is too small");
68 head()->setSize(size);
69 _size = size;
70 _count = 1;
71 init_statistics();
72 #ifndef PRODUCT
73 _allocation_stats.set_returnedBytes(_size * HeapWordSize);
74 #endif
75 }
76
77 void FreeList::reset(size_t hint) {
78 set_count(0);
79 set_head(NULL);
80 set_tail(NULL);
81 set_hint(hint);
82 }
83
84 void FreeList::init_statistics() {
85 _allocation_stats.initialize();
86 }
87
88 FreeChunk* FreeList::getChunkAtHead() {
89 assert_proper_lock_protection();
90 assert(head() == NULL || head()->prev() == NULL, "list invariant");
91 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
92 FreeChunk* fc = head();
93 if (fc != NULL) {
94 FreeChunk* 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->linkPrev(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 void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
112 assert_proper_lock_protection();
113 assert(fl->count() == 0, "Precondition");
114 if (count() > 0) {
115 int k = 1;
116 fl->set_head(head()); n--;
117 FreeChunk* tl = head();
118 while (tl->next() != NULL && n > 0) {
119 tl = tl->next(); n--; k++;
120 }
121 assert(tl != NULL, "Loop Inv.");
122
123 // First, fix up the list we took from.
124 FreeChunk* new_head = tl->next();
125 set_head(new_head);
126 set_count(count() - k);
127 if (new_head == NULL) {
128 set_tail(NULL);
129 } else {
130 new_head->linkPrev(NULL);
131 }
132 // Now we can fix up the tail.
133 tl->linkNext(NULL);
134 // And return the result.
135 fl->set_tail(tl);
136 fl->set_count(k);
137 }
138 }
139
140 // Remove this chunk from the list
141 void FreeList::removeChunk(FreeChunk*fc) {
142 assert_proper_lock_protection();
143 assert(head() != NULL, "Remove from empty list");
144 assert(fc != NULL, "Remove a NULL chunk");
145 assert(size() == fc->size(), "Wrong list");
146 assert(head() == NULL || head()->prev() == NULL, "list invariant");
147 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
148
149 FreeChunk* prevFC = fc->prev();
150 FreeChunk* nextFC = fc->next();
151 if (nextFC != NULL) {
152 // The chunk fc being removed has a "next". Set the "next" to the
153 // "prev" of fc.
154 nextFC->linkPrev(prevFC);
155 } else { // removed tail of list
156 link_tail(prevFC);
157 }
158 if (prevFC == NULL) { // removed head of list
159 link_head(nextFC);
160 assert(nextFC == NULL || nextFC->prev() == NULL,
161 "Prev of head should be NULL");
162 } else {
163 prevFC->linkNext(nextFC);
164 assert(tail() != prevFC || prevFC->next() == NULL,
165 "Next of tail should be NULL");
166 }
167 decrement_count();
168 #define TRAP_CODE 1
169 #if TRAP_CODE
170 if (head() == NULL) {
171 guarantee(tail() == NULL, "INVARIANT");
172 guarantee(count() == 0, "INVARIANT");
173 }
174 #endif
175 // clear next and prev fields of fc, debug only
176 NOT_PRODUCT(
177 fc->linkPrev(NULL);
178 fc->linkNext(NULL);
179 )
180 assert(fc->isFree(), "Should still be a free chunk");
181 assert(head() == NULL || head()->prev() == NULL, "list invariant");
182 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
183 assert(head() == NULL || head()->size() == size(), "wrong item on list");
184 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
185 }
186
187 // Add this chunk at the head of the list.
188 void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
189 assert_proper_lock_protection();
190 assert(chunk != NULL, "insert a NULL chunk");
191 assert(size() == chunk->size(), "Wrong size");
192 assert(head() == NULL || head()->prev() == NULL, "list invariant");
193 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
194
195 FreeChunk* oldHead = head();
196 assert(chunk != oldHead, "double insertion");
197 chunk->linkAfter(oldHead);
198 link_head(chunk);
199 if (oldHead == NULL) { // only chunk in list
200 assert(tail() == NULL, "inconsistent FreeList");
201 link_tail(chunk);
202 }
203 increment_count(); // of # of chunks in list
204 DEBUG_ONLY(
205 if (record_return) {
206 increment_returnedBytes_by(size()*HeapWordSize);
207 }
208 )
209 assert(head() == NULL || head()->prev() == NULL, "list invariant");
210 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
211 assert(head() == NULL || head()->size() == size(), "wrong item on list");
212 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
213 }
214
215 void FreeList::returnChunkAtHead(FreeChunk* chunk) {
216 assert_proper_lock_protection();
217 returnChunkAtHead(chunk, true);
218 }
219
220 // Add this chunk at the tail of the list.
221 void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
222 assert_proper_lock_protection();
223 assert(head() == NULL || head()->prev() == NULL, "list invariant");
224 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
225 assert(chunk != NULL, "insert a NULL chunk");
226 assert(size() == chunk->size(), "wrong size");
227
228 FreeChunk* oldTail = tail();
229 assert(chunk != oldTail, "double insertion");
230 if (oldTail != NULL) {
231 oldTail->linkAfter(chunk);
232 } else { // only chunk in list
233 assert(head() == NULL, "inconsistent FreeList");
234 link_head(chunk);
235 }
236 link_tail(chunk);
237 increment_count(); // of # of chunks in list
238 DEBUG_ONLY(
239 if (record_return) {
240 increment_returnedBytes_by(size()*HeapWordSize);
241 }
242 )
243 assert(head() == NULL || head()->prev() == NULL, "list invariant");
244 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
245 assert(head() == NULL || head()->size() == size(), "wrong item on list");
246 assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
247 }
248
249 void FreeList::returnChunkAtTail(FreeChunk* chunk) {
250 returnChunkAtTail(chunk, true);
251 }
252
253 void FreeList::prepend(FreeList* fl) {
254 assert_proper_lock_protection();
255 if (fl->count() > 0) {
256 if (count() == 0) {
257 set_head(fl->head());
258 set_tail(fl->tail());
259 set_count(fl->count());
260 } else {
261 // Both are non-empty.
262 FreeChunk* fl_tail = fl->tail();
263 FreeChunk* this_head = head();
264 assert(fl_tail->next() == NULL, "Well-formedness of fl");
265 fl_tail->linkNext(this_head);
266 this_head->linkPrev(fl_tail);
267 set_head(fl->head());
268 set_count(count() + fl->count());
269 }
270 fl->set_head(NULL);
271 fl->set_tail(NULL);
272 fl->set_count(0);
273 }
274 }
275
276 // verifyChunkInFreeLists() is used to verify that an item is in this free list.
277 // It is used as a debugging aid.
278 bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
279 // This is an internal consistency check, not part of the check that the
280 // chunk is in the free lists.
281 guarantee(fc->size() == size(), "Wrong list is being searched");
282 FreeChunk* curFC = head();
283 while (curFC) {
284 // This is an internal consistency check.
285 guarantee(size() == curFC->size(), "Chunk is in wrong list.");
286 if (fc == curFC) {
287 return true;
288 }
289 curFC = curFC->next();
290 }
291 return false;
292 }
293
294 #ifndef PRODUCT
295 void FreeList::assert_proper_lock_protection_work() const {
296 #ifdef ASSERT
297 if (_protecting_lock != NULL &&
298 SharedHeap::heap()->n_par_threads() > 0) {
299 // Should become an assert.
300 guarantee(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
301 }
302 #endif
303 }
304 #endif