1 /* 2 * Copyright (c) 2001, 2015, 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 "gc/shared/collectedHeap.hpp" 27 #include "memory/freeBlockDictionary.hpp" 28 #include "memory/freeList.hpp" 29 #include "memory/metachunk.hpp" 30 #include "runtime/globals.hpp" 31 #include "runtime/mutex.hpp" 32 #include "runtime/vmThread.hpp" 33 #include "utilities/macros.hpp" 34 #if INCLUDE_ALL_GCS 35 #include "gc/cms/freeChunk.hpp" 36 #endif // INCLUDE_ALL_GCS 37 38 // Free list. A FreeList is used to access a linked list of chunks 39 // of space in the heap. The head and tail are maintained so that 40 // items can be (as in the current implementation) added at the 41 // at the tail of the list and removed from the head of the list to 42 // maintain a FIFO queue. 43 44 template <class Chunk> 45 FreeList<Chunk>::FreeList() : 46 _head(NULL), _tail(NULL) 47 #ifdef ASSERT 48 , _protecting_lock(NULL) 49 #endif 50 { 51 _size = 0; 52 _count = 0; 53 } 54 55 template <class Chunk> 56 void FreeList<Chunk>::link_head(Chunk* v) { 57 assert_proper_lock_protection(); 58 set_head(v); 59 // If this method is not used (just set the head instead), 60 // this check can be avoided. 61 if (v != NULL) { 62 v->link_prev(NULL); 63 } 64 } 65 66 67 68 template <class Chunk> 69 void FreeList<Chunk>::reset() { 70 // Don't set the _size to 0 because this method is 71 // used with a existing list that has a size but which has 72 // been emptied. 73 // Don't clear the _protecting_lock of an existing list. 74 set_count(0); 75 set_head(NULL); 76 set_tail(NULL); 77 } 78 79 template <class Chunk> 80 void FreeList<Chunk>::initialize() { 81 #ifdef ASSERT 82 // Needed early because it might be checked in other initializing code. 83 set_protecting_lock(NULL); 84 #endif 85 reset(); 86 set_size(0); 87 } 88 89 template <class Chunk_t> 90 Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() { 91 assert_proper_lock_protection(); 92 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 93 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 94 Chunk_t* fc = head(); 95 if (fc != NULL) { 96 Chunk_t* nextFC = fc->next(); 97 if (nextFC != NULL) { 98 // The chunk fc being removed has a "next". Set the "next" to the 99 // "prev" of fc. 100 nextFC->link_prev(NULL); 101 } else { // removed tail of list 102 link_tail(NULL); 103 } 104 link_head(nextFC); 105 decrement_count(); 106 } 107 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 108 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 109 return fc; 110 } 111 112 113 template <class Chunk> 114 void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) { 115 assert_proper_lock_protection(); 116 assert(fl->count() == 0, "Precondition"); 117 if (count() > 0) { 118 int k = 1; 119 fl->set_head(head()); n--; 120 Chunk* tl = head(); 121 while (tl->next() != NULL && n > 0) { 122 tl = tl->next(); n--; k++; 123 } 124 assert(tl != NULL, "Loop Inv."); 125 126 // First, fix up the list we took from. 127 Chunk* new_head = tl->next(); 128 set_head(new_head); 129 set_count(count() - k); 130 if (new_head == NULL) { 131 set_tail(NULL); 132 } else { 133 new_head->link_prev(NULL); 134 } 135 // Now we can fix up the tail. 136 tl->link_next(NULL); 137 // And return the result. 138 fl->set_tail(tl); 139 fl->set_count(k); 140 } 141 } 142 143 // Remove this chunk from the list 144 template <class Chunk> 145 void FreeList<Chunk>::remove_chunk(Chunk*fc) { 146 assert_proper_lock_protection(); 147 assert(head() != NULL, "Remove from empty list"); 148 assert(fc != NULL, "Remove a NULL chunk"); 149 assert(size() == fc->size(), "Wrong list"); 150 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 151 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 152 153 Chunk* prevFC = fc->prev(); 154 Chunk* nextFC = fc->next(); 155 if (nextFC != NULL) { 156 // The chunk fc being removed has a "next". Set the "next" to the 157 // "prev" of fc. 158 nextFC->link_prev(prevFC); 159 } else { // removed tail of list 160 link_tail(prevFC); 161 } 162 if (prevFC == NULL) { // removed head of list 163 link_head(nextFC); 164 assert(nextFC == NULL || nextFC->prev() == NULL, 165 "Prev of head should be NULL"); 166 } else { 167 prevFC->link_next(nextFC); 168 assert(tail() != prevFC || prevFC->next() == NULL, 169 "Next of tail should be NULL"); 170 } 171 decrement_count(); 172 assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0, 173 "H/T/C Inconsistency"); 174 // clear next and prev fields of fc, debug only 175 NOT_PRODUCT( 176 fc->link_prev(NULL); 177 fc->link_next(NULL); 178 ) 179 assert(fc->is_free(), "Should still be a free chunk"); 180 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 181 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 182 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 183 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 184 } 185 186 // Add this chunk at the head of the list. 187 template <class Chunk> 188 void FreeList<Chunk>::return_chunk_at_head(Chunk* 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 Chunk* oldHead = head(); 196 assert(chunk != oldHead, "double insertion"); 197 chunk->link_after(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 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 205 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 206 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 207 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 208 } 209 210 template <class Chunk> 211 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) { 212 assert_proper_lock_protection(); 213 return_chunk_at_head(chunk, true); 214 } 215 216 // Add this chunk at the tail of the list. 217 template <class Chunk> 218 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk, bool record_return) { 219 assert_proper_lock_protection(); 220 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 221 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 222 assert(chunk != NULL, "insert a NULL chunk"); 223 assert(size() == chunk->size(), "wrong size"); 224 225 Chunk* oldTail = tail(); 226 assert(chunk != oldTail, "double insertion"); 227 if (oldTail != NULL) { 228 oldTail->link_after(chunk); 229 } else { // only chunk in list 230 assert(head() == NULL, "inconsistent FreeList"); 231 link_head(chunk); 232 } 233 link_tail(chunk); 234 increment_count(); // of # of chunks in list 235 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 236 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 237 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 238 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 239 } 240 241 template <class Chunk> 242 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) { 243 return_chunk_at_tail(chunk, true); 244 } 245 246 template <class Chunk> 247 void FreeList<Chunk>::prepend(FreeList<Chunk>* fl) { 248 assert_proper_lock_protection(); 249 if (fl->count() > 0) { 250 if (count() == 0) { 251 set_head(fl->head()); 252 set_tail(fl->tail()); 253 set_count(fl->count()); 254 } else { 255 // Both are non-empty. 256 Chunk* fl_tail = fl->tail(); 257 Chunk* this_head = head(); 258 assert(fl_tail->next() == NULL, "Well-formedness of fl"); 259 fl_tail->link_next(this_head); 260 this_head->link_prev(fl_tail); 261 set_head(fl->head()); 262 set_count(count() + fl->count()); 263 } 264 fl->set_head(NULL); 265 fl->set_tail(NULL); 266 fl->set_count(0); 267 } 268 } 269 270 // verify_chunk_in_free_lists() is used to verify that an item is in this free list. 271 // It is used as a debugging aid. 272 template <class Chunk> 273 bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* fc) const { 274 // This is an internal consistency check, not part of the check that the 275 // chunk is in the free lists. 276 guarantee(fc->size() == size(), "Wrong list is being searched"); 277 Chunk* curFC = head(); 278 while (curFC) { 279 // This is an internal consistency check. 280 guarantee(size() == curFC->size(), "Chunk is in wrong list."); 281 if (fc == curFC) { 282 return true; 283 } 284 curFC = curFC->next(); 285 } 286 return false; 287 } 288 289 #ifdef ASSERT 290 template <class Chunk> 291 void FreeList<Chunk>::assert_proper_lock_protection_work() const { 292 // Nothing to do if the list has no assigned protecting lock 293 if (protecting_lock() == NULL) { 294 return; 295 } 296 297 Thread* thr = Thread::current(); 298 if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) { 299 // assert that we are holding the freelist lock 300 } else if (thr->is_GC_task_thread()) { 301 assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED"); 302 } else if (thr->is_Java_thread()) { 303 assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing"); 304 } else { 305 ShouldNotReachHere(); // unaccounted thread type? 306 } 307 } 308 #endif 309 310 // Print the "label line" for free list stats. 311 template <class Chunk> 312 void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) { 313 st->print("%16s\t", c); 314 st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" 315 "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n", 316 "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep", 317 "count", "cBirths", "cDeaths", "sBirths", "sDeaths"); 318 } 319 320 // Print the AllocationStats for the given free list. If the second argument 321 // to the call is a non-null string, it is printed in the first column; 322 // otherwise, if the argument is null (the default), then the size of the 323 // (free list) block is printed in the first column. 324 template <class Chunk_t> 325 void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const { 326 if (c != NULL) { 327 st->print("%16s", c); 328 } else { 329 st->print(SIZE_FORMAT_W(16), size()); 330 } 331 } 332 333 template class FreeList<Metablock>; 334 template class FreeList<Metachunk>; 335 #if INCLUDE_ALL_GCS 336 template class FreeList<FreeChunk>; 337 #endif // INCLUDE_ALL_GCS