1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/freeList.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,304 @@
1.4 +/*
1.5 + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_freeList.cpp.incl"
1.30 +
1.31 +// Free list. A FreeList is used to access a linked list of chunks
1.32 +// of space in the heap. The head and tail are maintained so that
1.33 +// items can be (as in the current implementation) added at the
1.34 +// at the tail of the list and removed from the head of the list to
1.35 +// maintain a FIFO queue.
1.36 +
1.37 +FreeList::FreeList() :
1.38 + _head(NULL), _tail(NULL)
1.39 +#ifdef ASSERT
1.40 + , _protecting_lock(NULL)
1.41 +#endif
1.42 +{
1.43 + _size = 0;
1.44 + _count = 0;
1.45 + _hint = 0;
1.46 + init_statistics();
1.47 +}
1.48 +
1.49 +FreeList::FreeList(FreeChunk* fc) :
1.50 + _head(fc), _tail(fc)
1.51 +#ifdef ASSERT
1.52 + , _protecting_lock(NULL)
1.53 +#endif
1.54 +{
1.55 + _size = fc->size();
1.56 + _count = 1;
1.57 + _hint = 0;
1.58 + init_statistics();
1.59 +#ifndef PRODUCT
1.60 + _allocation_stats.set_returnedBytes(size() * HeapWordSize);
1.61 +#endif
1.62 +}
1.63 +
1.64 +FreeList::FreeList(HeapWord* addr, size_t size) :
1.65 + _head((FreeChunk*) addr), _tail((FreeChunk*) addr)
1.66 +#ifdef ASSERT
1.67 + , _protecting_lock(NULL)
1.68 +#endif
1.69 +{
1.70 + assert(size > sizeof(FreeChunk), "size is too small");
1.71 + head()->setSize(size);
1.72 + _size = size;
1.73 + _count = 1;
1.74 + init_statistics();
1.75 +#ifndef PRODUCT
1.76 + _allocation_stats.set_returnedBytes(_size * HeapWordSize);
1.77 +#endif
1.78 +}
1.79 +
1.80 +void FreeList::reset(size_t hint) {
1.81 + set_count(0);
1.82 + set_head(NULL);
1.83 + set_tail(NULL);
1.84 + set_hint(hint);
1.85 +}
1.86 +
1.87 +void FreeList::init_statistics() {
1.88 + _allocation_stats.initialize();
1.89 +}
1.90 +
1.91 +FreeChunk* FreeList::getChunkAtHead() {
1.92 + assert_proper_lock_protection();
1.93 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.94 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.95 + FreeChunk* fc = head();
1.96 + if (fc != NULL) {
1.97 + FreeChunk* nextFC = fc->next();
1.98 + if (nextFC != NULL) {
1.99 + // The chunk fc being removed has a "next". Set the "next" to the
1.100 + // "prev" of fc.
1.101 + nextFC->linkPrev(NULL);
1.102 + } else { // removed tail of list
1.103 + link_tail(NULL);
1.104 + }
1.105 + link_head(nextFC);
1.106 + decrement_count();
1.107 + }
1.108 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.109 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.110 + return fc;
1.111 +}
1.112 +
1.113 +
1.114 +void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
1.115 + assert_proper_lock_protection();
1.116 + assert(fl->count() == 0, "Precondition");
1.117 + if (count() > 0) {
1.118 + int k = 1;
1.119 + fl->set_head(head()); n--;
1.120 + FreeChunk* tl = head();
1.121 + while (tl->next() != NULL && n > 0) {
1.122 + tl = tl->next(); n--; k++;
1.123 + }
1.124 + assert(tl != NULL, "Loop Inv.");
1.125 +
1.126 + // First, fix up the list we took from.
1.127 + FreeChunk* new_head = tl->next();
1.128 + set_head(new_head);
1.129 + set_count(count() - k);
1.130 + if (new_head == NULL) {
1.131 + set_tail(NULL);
1.132 + } else {
1.133 + new_head->linkPrev(NULL);
1.134 + }
1.135 + // Now we can fix up the tail.
1.136 + tl->linkNext(NULL);
1.137 + // And return the result.
1.138 + fl->set_tail(tl);
1.139 + fl->set_count(k);
1.140 + }
1.141 +}
1.142 +
1.143 +// Remove this chunk from the list
1.144 +void FreeList::removeChunk(FreeChunk*fc) {
1.145 + assert_proper_lock_protection();
1.146 + assert(head() != NULL, "Remove from empty list");
1.147 + assert(fc != NULL, "Remove a NULL chunk");
1.148 + assert(size() == fc->size(), "Wrong list");
1.149 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.150 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.151 +
1.152 + FreeChunk* prevFC = fc->prev();
1.153 + FreeChunk* nextFC = fc->next();
1.154 + if (nextFC != NULL) {
1.155 + // The chunk fc being removed has a "next". Set the "next" to the
1.156 + // "prev" of fc.
1.157 + nextFC->linkPrev(prevFC);
1.158 + } else { // removed tail of list
1.159 + link_tail(prevFC);
1.160 + }
1.161 + if (prevFC == NULL) { // removed head of list
1.162 + link_head(nextFC);
1.163 + assert(nextFC == NULL || nextFC->prev() == NULL,
1.164 + "Prev of head should be NULL");
1.165 + } else {
1.166 + prevFC->linkNext(nextFC);
1.167 + assert(tail() != prevFC || prevFC->next() == NULL,
1.168 + "Next of tail should be NULL");
1.169 + }
1.170 + decrement_count();
1.171 +#define TRAP_CODE 1
1.172 +#if TRAP_CODE
1.173 + if (head() == NULL) {
1.174 + guarantee(tail() == NULL, "INVARIANT");
1.175 + guarantee(count() == 0, "INVARIANT");
1.176 + }
1.177 +#endif
1.178 + // clear next and prev fields of fc, debug only
1.179 + NOT_PRODUCT(
1.180 + fc->linkPrev(NULL);
1.181 + fc->linkNext(NULL);
1.182 + )
1.183 + assert(fc->isFree(), "Should still be a free chunk");
1.184 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.185 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.186 + assert(head() == NULL || head()->size() == size(), "wrong item on list");
1.187 + assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
1.188 +}
1.189 +
1.190 +// Add this chunk at the head of the list.
1.191 +void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
1.192 + assert_proper_lock_protection();
1.193 + assert(chunk != NULL, "insert a NULL chunk");
1.194 + assert(size() == chunk->size(), "Wrong size");
1.195 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.196 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.197 +
1.198 + FreeChunk* oldHead = head();
1.199 + assert(chunk != oldHead, "double insertion");
1.200 + chunk->linkAfter(oldHead);
1.201 + link_head(chunk);
1.202 + if (oldHead == NULL) { // only chunk in list
1.203 + assert(tail() == NULL, "inconsistent FreeList");
1.204 + link_tail(chunk);
1.205 + }
1.206 + increment_count(); // of # of chunks in list
1.207 + DEBUG_ONLY(
1.208 + if (record_return) {
1.209 + increment_returnedBytes_by(size()*HeapWordSize);
1.210 + }
1.211 + )
1.212 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.213 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.214 + assert(head() == NULL || head()->size() == size(), "wrong item on list");
1.215 + assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
1.216 +}
1.217 +
1.218 +void FreeList::returnChunkAtHead(FreeChunk* chunk) {
1.219 + assert_proper_lock_protection();
1.220 + returnChunkAtHead(chunk, true);
1.221 +}
1.222 +
1.223 +// Add this chunk at the tail of the list.
1.224 +void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
1.225 + assert_proper_lock_protection();
1.226 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.227 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.228 + assert(chunk != NULL, "insert a NULL chunk");
1.229 + assert(size() == chunk->size(), "wrong size");
1.230 +
1.231 + FreeChunk* oldTail = tail();
1.232 + assert(chunk != oldTail, "double insertion");
1.233 + if (oldTail != NULL) {
1.234 + oldTail->linkAfter(chunk);
1.235 + } else { // only chunk in list
1.236 + assert(head() == NULL, "inconsistent FreeList");
1.237 + link_head(chunk);
1.238 + }
1.239 + link_tail(chunk);
1.240 + increment_count(); // of # of chunks in list
1.241 + DEBUG_ONLY(
1.242 + if (record_return) {
1.243 + increment_returnedBytes_by(size()*HeapWordSize);
1.244 + }
1.245 + )
1.246 + assert(head() == NULL || head()->prev() == NULL, "list invariant");
1.247 + assert(tail() == NULL || tail()->next() == NULL, "list invariant");
1.248 + assert(head() == NULL || head()->size() == size(), "wrong item on list");
1.249 + assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
1.250 +}
1.251 +
1.252 +void FreeList::returnChunkAtTail(FreeChunk* chunk) {
1.253 + returnChunkAtTail(chunk, true);
1.254 +}
1.255 +
1.256 +void FreeList::prepend(FreeList* fl) {
1.257 + assert_proper_lock_protection();
1.258 + if (fl->count() > 0) {
1.259 + if (count() == 0) {
1.260 + set_head(fl->head());
1.261 + set_tail(fl->tail());
1.262 + set_count(fl->count());
1.263 + } else {
1.264 + // Both are non-empty.
1.265 + FreeChunk* fl_tail = fl->tail();
1.266 + FreeChunk* this_head = head();
1.267 + assert(fl_tail->next() == NULL, "Well-formedness of fl");
1.268 + fl_tail->linkNext(this_head);
1.269 + this_head->linkPrev(fl_tail);
1.270 + set_head(fl->head());
1.271 + set_count(count() + fl->count());
1.272 + }
1.273 + fl->set_head(NULL);
1.274 + fl->set_tail(NULL);
1.275 + fl->set_count(0);
1.276 + }
1.277 +}
1.278 +
1.279 +// verifyChunkInFreeLists() is used to verify that an item is in this free list.
1.280 +// It is used as a debugging aid.
1.281 +bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
1.282 + // This is an internal consistency check, not part of the check that the
1.283 + // chunk is in the free lists.
1.284 + guarantee(fc->size() == size(), "Wrong list is being searched");
1.285 + FreeChunk* curFC = head();
1.286 + while (curFC) {
1.287 + // This is an internal consistency check.
1.288 + guarantee(size() == curFC->size(), "Chunk is in wrong list.");
1.289 + if (fc == curFC) {
1.290 + return true;
1.291 + }
1.292 + curFC = curFC->next();
1.293 + }
1.294 + return false;
1.295 +}
1.296 +
1.297 +#ifndef PRODUCT
1.298 +void FreeList::assert_proper_lock_protection_work() const {
1.299 +#ifdef ASSERT
1.300 + if (_protecting_lock != NULL &&
1.301 + SharedHeap::heap()->n_par_threads() > 0) {
1.302 + // Should become an assert.
1.303 + guarantee(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
1.304 + }
1.305 +#endif
1.306 +}
1.307 +#endif
