1 /*
2 * Copyright (c) 2001, 2008, 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 class CompactibleFreeListSpace;
26
27 // A class for maintaining a free list of FreeChunk's. The FreeList
28 // maintains a the structure of the list (head, tail, etc.) plus
29 // statistics for allocations from the list. The links between items
30 // are not part of FreeList. The statistics are
31 // used to make decisions about coalescing FreeChunk's when they
32 // are swept during collection.
33 //
34 // See the corresponding .cpp file for a description of the specifics
35 // for that implementation.
36
37 class Mutex;
38 class TreeList;
39
40 class FreeList VALUE_OBJ_CLASS_SPEC {
41 friend class CompactibleFreeListSpace;
42 friend class VMStructs;
43 friend class PrintTreeCensusClosure;
44
45 protected:
46 TreeList* _parent;
47 TreeList* _left;
48 TreeList* _right;
49
50 private:
51 FreeChunk* _head; // Head of list of free chunks
52 FreeChunk* _tail; // Tail of list of free chunks
53 size_t _size; // Size in Heap words of each chunk
54 ssize_t _count; // Number of entries in list
55 size_t _hint; // next larger size list with a positive surplus
56
57 AllocationStats _allocation_stats; // allocation-related statistics
58
59 #ifdef ASSERT
60 Mutex* _protecting_lock;
61 #endif
62
63 // Asserts false if the protecting lock (if any) is not held.
64 void assert_proper_lock_protection_work() const PRODUCT_RETURN;
65 void assert_proper_lock_protection() const {
66 #ifdef ASSERT
67 if (_protecting_lock != NULL)
68 assert_proper_lock_protection_work();
69 #endif
70 }
71
72 // Initialize the allocation statistics.
73 protected:
74 void init_statistics(bool split_birth = false);
75 void set_count(ssize_t v) { _count = v;}
76 void increment_count() {
77 _count++;
78 }
79
80 void decrement_count() {
81 _count--;
82 assert(_count >= 0, "Count should not be negative");
83 }
84
85 public:
86 // Constructor
87 // Construct a list without any entries.
88 FreeList();
89 // Construct a list with "fc" as the first (and lone) entry in the list.
90 FreeList(FreeChunk* fc);
91 // Construct a list which will have a FreeChunk at address "addr" and
92 // of size "size" as the first (and lone) entry in the list.
93 FreeList(HeapWord* addr, size_t size);
94
95 // Reset the head, tail, hint, and count of a free list.
96 void reset(size_t hint);
97
98 // Declare the current free list to be protected by the given lock.
99 #ifdef ASSERT
100 void set_protecting_lock(Mutex* protecting_lock) {
101 _protecting_lock = protecting_lock;
102 }
103 #endif
104
105 // Accessors.
106 FreeChunk* head() const {
107 assert_proper_lock_protection();
108 return _head;
109 }
110 void set_head(FreeChunk* v) {
111 assert_proper_lock_protection();
112 _head = v;
113 assert(!_head || _head->size() == _size, "bad chunk size");
114 }
115 // Set the head of the list and set the prev field of non-null
116 // values to NULL.
117 void link_head(FreeChunk* v) {
118 assert_proper_lock_protection();
119 set_head(v);
120 // If this method is not used (just set the head instead),
121 // this check can be avoided.
122 if (v != NULL) {
123 v->linkPrev(NULL);
124 }
125 }
126
127 FreeChunk* tail() const {
128 assert_proper_lock_protection();
129 return _tail;
130 }
131 void set_tail(FreeChunk* v) {
132 assert_proper_lock_protection();
133 _tail = v;
134 assert(!_tail || _tail->size() == _size, "bad chunk size");
135 }
136 // Set the tail of the list and set the next field of non-null
137 // values to NULL.
138 void link_tail(FreeChunk* v) {
139 assert_proper_lock_protection();
140 set_tail(v);
141 if (v != NULL) {
142 v->clearNext();
143 }
144 }
145
146 // No locking checks in read-accessors: lock-free reads (only) are benign.
147 // Readers are expected to have the lock if they are doing work that
148 // requires atomicity guarantees in sections of code.
149 size_t size() const {
150 return _size;
151 }
152 void set_size(size_t v) {
153 assert_proper_lock_protection();
154 _size = v;
155 }
156 ssize_t count() const {
157 return _count;
158 }
159 size_t hint() const {
160 return _hint;
161 }
162 void set_hint(size_t v) {
163 assert_proper_lock_protection();
164 assert(v == 0 || _size < v, "Bad hint"); _hint = v;
165 }
166
167 // Accessors for statistics
168 AllocationStats* allocation_stats() {
169 assert_proper_lock_protection();
170 return &_allocation_stats;
171 }
172
173 ssize_t desired() const {
174 return _allocation_stats.desired();
175 }
176 void set_desired(ssize_t v) {
177 assert_proper_lock_protection();
178 _allocation_stats.set_desired(v);
179 }
180 void compute_desired(float inter_sweep_current,
181 float inter_sweep_estimate,
182 float intra_sweep_estimate) {
183 assert_proper_lock_protection();
184 _allocation_stats.compute_desired(_count,
185 inter_sweep_current,
186 inter_sweep_estimate,
187 intra_sweep_estimate);
188 }
189 ssize_t coalDesired() const {
190 return _allocation_stats.coalDesired();
191 }
192 void set_coalDesired(ssize_t v) {
193 assert_proper_lock_protection();
194 _allocation_stats.set_coalDesired(v);
195 }
196
197 ssize_t surplus() const {
198 return _allocation_stats.surplus();
199 }
200 void set_surplus(ssize_t v) {
201 assert_proper_lock_protection();
202 _allocation_stats.set_surplus(v);
203 }
204 void increment_surplus() {
205 assert_proper_lock_protection();
206 _allocation_stats.increment_surplus();
207 }
208 void decrement_surplus() {
209 assert_proper_lock_protection();
210 _allocation_stats.decrement_surplus();
211 }
212
213 ssize_t bfrSurp() const {
214 return _allocation_stats.bfrSurp();
215 }
216 void set_bfrSurp(ssize_t v) {
217 assert_proper_lock_protection();
218 _allocation_stats.set_bfrSurp(v);
219 }
220 ssize_t prevSweep() const {
221 return _allocation_stats.prevSweep();
222 }
223 void set_prevSweep(ssize_t v) {
224 assert_proper_lock_protection();
225 _allocation_stats.set_prevSweep(v);
226 }
227 ssize_t beforeSweep() const {
228 return _allocation_stats.beforeSweep();
229 }
230 void set_beforeSweep(ssize_t v) {
231 assert_proper_lock_protection();
232 _allocation_stats.set_beforeSweep(v);
233 }
234
235 ssize_t coalBirths() const {
236 return _allocation_stats.coalBirths();
237 }
238 void set_coalBirths(ssize_t v) {
239 assert_proper_lock_protection();
240 _allocation_stats.set_coalBirths(v);
241 }
242 void increment_coalBirths() {
243 assert_proper_lock_protection();
244 _allocation_stats.increment_coalBirths();
245 }
246
247 ssize_t coalDeaths() const {
248 return _allocation_stats.coalDeaths();
249 }
250 void set_coalDeaths(ssize_t v) {
251 assert_proper_lock_protection();
252 _allocation_stats.set_coalDeaths(v);
253 }
254 void increment_coalDeaths() {
255 assert_proper_lock_protection();
256 _allocation_stats.increment_coalDeaths();
257 }
258
259 ssize_t splitBirths() const {
260 return _allocation_stats.splitBirths();
261 }
262 void set_splitBirths(ssize_t v) {
263 assert_proper_lock_protection();
264 _allocation_stats.set_splitBirths(v);
265 }
266 void increment_splitBirths() {
267 assert_proper_lock_protection();
268 _allocation_stats.increment_splitBirths();
269 }
270
271 ssize_t splitDeaths() const {
272 return _allocation_stats.splitDeaths();
273 }
274 void set_splitDeaths(ssize_t v) {
275 assert_proper_lock_protection();
276 _allocation_stats.set_splitDeaths(v);
277 }
278 void increment_splitDeaths() {
279 assert_proper_lock_protection();
280 _allocation_stats.increment_splitDeaths();
281 }
282
283 NOT_PRODUCT(
284 // For debugging. The "_returnedBytes" in all the lists are summed
285 // and compared with the total number of bytes swept during a
286 // collection.
287 size_t returnedBytes() const { return _allocation_stats.returnedBytes(); }
288 void set_returnedBytes(size_t v) { _allocation_stats.set_returnedBytes(v); }
289 void increment_returnedBytes_by(size_t v) {
290 _allocation_stats.set_returnedBytes(_allocation_stats.returnedBytes() + v);
291 }
292 )
293
294 // Unlink head of list and return it. Returns NULL if
295 // the list is empty.
296 FreeChunk* getChunkAtHead();
297
298 // Remove the first "n" or "count", whichever is smaller, chunks from the
299 // list, setting "fl", which is required to be empty, to point to them.
300 void getFirstNChunksFromList(size_t n, FreeList* fl);
301
302 // Unlink this chunk from it's free list
303 void removeChunk(FreeChunk* fc);
304
305 // Add this chunk to this free list.
306 void returnChunkAtHead(FreeChunk* fc);
307 void returnChunkAtTail(FreeChunk* fc);
308
309 // Similar to returnChunk* but also records some diagnostic
310 // information.
311 void returnChunkAtHead(FreeChunk* fc, bool record_return);
312 void returnChunkAtTail(FreeChunk* fc, bool record_return);
313
314 // Prepend "fl" (whose size is required to be the same as that of "this")
315 // to the front of "this" list.
316 void prepend(FreeList* fl);
317
318 // Verify that the chunk is in the list.
319 // found. Return NULL if "fc" is not found.
320 bool verifyChunkInFreeLists(FreeChunk* fc) const;
321
322 // Stats verification
323 void verify_stats() const PRODUCT_RETURN;
324
325 // Printing support
326 static void print_labels_on(outputStream* st, const char* c);
327 void print_on(outputStream* st, const char* c = NULL) const;
328 };