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view src/share/vm/gc_implementation/concurrentMarkSweep/freeList.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 6432c3bb6240 |
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/* * 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