--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/freeList.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,304 @@
+/*
+ * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_freeList.cpp.incl"
+
+// Free list. A FreeList is used to access a linked list of chunks
+// of space in the heap. The head and tail are maintained so that
+// items can be (as in the current implementation) added at the
+// at the tail of the list and removed from the head of the list to
+// maintain a FIFO queue.
+
+FreeList::FreeList() :
+ _head(NULL), _tail(NULL)
+#ifdef ASSERT
+ , _protecting_lock(NULL)
+#endif
+{
+ _size = 0;
+ _count = 0;
+ _hint = 0;
+ init_statistics();
+}
+
+FreeList::FreeList(FreeChunk* fc) :
+ _head(fc), _tail(fc)
+#ifdef ASSERT
+ , _protecting_lock(NULL)
+#endif
+{
+ _size = fc->size();
+ _count = 1;
+ _hint = 0;
+ init_statistics();
+#ifndef PRODUCT
+ _allocation_stats.set_returnedBytes(size() * HeapWordSize);
+#endif
+}
+
+FreeList::FreeList(HeapWord* addr, size_t size) :
+ _head((FreeChunk*) addr), _tail((FreeChunk*) addr)
+#ifdef ASSERT
+ , _protecting_lock(NULL)
+#endif
+{
+ assert(size > sizeof(FreeChunk), "size is too small");
+ head()->setSize(size);
+ _size = size;
+ _count = 1;
+ init_statistics();
+#ifndef PRODUCT
+ _allocation_stats.set_returnedBytes(_size * HeapWordSize);
+#endif
+}
+
+void FreeList::reset(size_t hint) {
+ set_count(0);
+ set_head(NULL);
+ set_tail(NULL);
+ set_hint(hint);
+}
+
+void FreeList::init_statistics() {
+ _allocation_stats.initialize();
+}
+
+FreeChunk* FreeList::getChunkAtHead() {
+ assert_proper_lock_protection();
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ FreeChunk* fc = head();
+ if (fc != NULL) {
+ FreeChunk* nextFC = fc->next();
+ if (nextFC != NULL) {
+ // The chunk fc being removed has a "next". Set the "next" to the
+ // "prev" of fc.
+ nextFC->linkPrev(NULL);
+ } else { // removed tail of list
+ link_tail(NULL);
+ }
+ link_head(nextFC);
+ decrement_count();
+ }
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ return fc;
+}
+
+
+void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
+ assert_proper_lock_protection();
+ assert(fl->count() == 0, "Precondition");
+ if (count() > 0) {
+ int k = 1;
+ fl->set_head(head()); n--;
+ FreeChunk* tl = head();
+ while (tl->next() != NULL && n > 0) {
+ tl = tl->next(); n--; k++;
+ }
+ assert(tl != NULL, "Loop Inv.");
+
+ // First, fix up the list we took from.
+ FreeChunk* new_head = tl->next();
+ set_head(new_head);
+ set_count(count() - k);
+ if (new_head == NULL) {
+ set_tail(NULL);
+ } else {
+ new_head->linkPrev(NULL);
+ }
+ // Now we can fix up the tail.
+ tl->linkNext(NULL);
+ // And return the result.
+ fl->set_tail(tl);
+ fl->set_count(k);
+ }
+}
+
+// Remove this chunk from the list
+void FreeList::removeChunk(FreeChunk*fc) {
+ assert_proper_lock_protection();
+ assert(head() != NULL, "Remove from empty list");
+ assert(fc != NULL, "Remove a NULL chunk");
+ assert(size() == fc->size(), "Wrong list");
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+
+ FreeChunk* prevFC = fc->prev();
+ FreeChunk* nextFC = fc->next();
+ if (nextFC != NULL) {
+ // The chunk fc being removed has a "next". Set the "next" to the
+ // "prev" of fc.
+ nextFC->linkPrev(prevFC);
+ } else { // removed tail of list
+ link_tail(prevFC);
+ }
+ if (prevFC == NULL) { // removed head of list
+ link_head(nextFC);
+ assert(nextFC == NULL || nextFC->prev() == NULL,
+ "Prev of head should be NULL");
+ } else {
+ prevFC->linkNext(nextFC);
+ assert(tail() != prevFC || prevFC->next() == NULL,
+ "Next of tail should be NULL");
+ }
+ decrement_count();
+#define TRAP_CODE 1
+#if TRAP_CODE
+ if (head() == NULL) {
+ guarantee(tail() == NULL, "INVARIANT");
+ guarantee(count() == 0, "INVARIANT");
+ }
+#endif
+ // clear next and prev fields of fc, debug only
+ NOT_PRODUCT(
+ fc->linkPrev(NULL);
+ fc->linkNext(NULL);
+ )
+ assert(fc->isFree(), "Should still be a free chunk");
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ assert(head() == NULL || head()->size() == size(), "wrong item on list");
+ assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
+}
+
+// Add this chunk at the head of the list.
+void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
+ assert_proper_lock_protection();
+ assert(chunk != NULL, "insert a NULL chunk");
+ assert(size() == chunk->size(), "Wrong size");
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+
+ FreeChunk* oldHead = head();
+ assert(chunk != oldHead, "double insertion");
+ chunk->linkAfter(oldHead);
+ link_head(chunk);
+ if (oldHead == NULL) { // only chunk in list
+ assert(tail() == NULL, "inconsistent FreeList");
+ link_tail(chunk);
+ }
+ increment_count(); // of # of chunks in list
+ DEBUG_ONLY(
+ if (record_return) {
+ increment_returnedBytes_by(size()*HeapWordSize);
+ }
+ )
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ assert(head() == NULL || head()->size() == size(), "wrong item on list");
+ assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
+}
+
+void FreeList::returnChunkAtHead(FreeChunk* chunk) {
+ assert_proper_lock_protection();
+ returnChunkAtHead(chunk, true);
+}
+
+// Add this chunk at the tail of the list.
+void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
+ assert_proper_lock_protection();
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ assert(chunk != NULL, "insert a NULL chunk");
+ assert(size() == chunk->size(), "wrong size");
+
+ FreeChunk* oldTail = tail();
+ assert(chunk != oldTail, "double insertion");
+ if (oldTail != NULL) {
+ oldTail->linkAfter(chunk);
+ } else { // only chunk in list
+ assert(head() == NULL, "inconsistent FreeList");
+ link_head(chunk);
+ }
+ link_tail(chunk);
+ increment_count(); // of # of chunks in list
+ DEBUG_ONLY(
+ if (record_return) {
+ increment_returnedBytes_by(size()*HeapWordSize);
+ }
+ )
+ assert(head() == NULL || head()->prev() == NULL, "list invariant");
+ assert(tail() == NULL || tail()->next() == NULL, "list invariant");
+ assert(head() == NULL || head()->size() == size(), "wrong item on list");
+ assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
+}
+
+void FreeList::returnChunkAtTail(FreeChunk* chunk) {
+ returnChunkAtTail(chunk, true);
+}
+
+void FreeList::prepend(FreeList* fl) {
+ assert_proper_lock_protection();
+ if (fl->count() > 0) {
+ if (count() == 0) {
+ set_head(fl->head());
+ set_tail(fl->tail());
+ set_count(fl->count());
+ } else {
+ // Both are non-empty.
+ FreeChunk* fl_tail = fl->tail();
+ FreeChunk* this_head = head();
+ assert(fl_tail->next() == NULL, "Well-formedness of fl");
+ fl_tail->linkNext(this_head);
+ this_head->linkPrev(fl_tail);
+ set_head(fl->head());
+ set_count(count() + fl->count());
+ }
+ fl->set_head(NULL);
+ fl->set_tail(NULL);
+ fl->set_count(0);
+ }
+}
+
+// verifyChunkInFreeLists() is used to verify that an item is in this free list.
+// It is used as a debugging aid.
+bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
+ // This is an internal consistency check, not part of the check that the
+ // chunk is in the free lists.
+ guarantee(fc->size() == size(), "Wrong list is being searched");
+ FreeChunk* curFC = head();
+ while (curFC) {
+ // This is an internal consistency check.
+ guarantee(size() == curFC->size(), "Chunk is in wrong list.");
+ if (fc == curFC) {
+ return true;
+ }
+ curFC = curFC->next();
+ }
+ return false;
+}
+
+#ifndef PRODUCT
+void FreeList::assert_proper_lock_protection_work() const {
+#ifdef ASSERT
+ if (_protecting_lock != NULL &&
+ SharedHeap::heap()->n_par_threads() > 0) {
+ // Should become an assert.
+ guarantee(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
+ }
+#endif
+}
+#endif