| /* |
| * Copyright (c) 2001, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc/shared/collectedHeap.hpp" |
| #include "memory/freeList.hpp" |
| #include "memory/metachunk.hpp" |
| #include "runtime/globals.hpp" |
| #include "runtime/mutex.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/macros.hpp" |
| #if INCLUDE_ALL_GCS |
| #include "gc/cms/freeChunk.hpp" |
| #endif // INCLUDE_ALL_GCS |
| |
| // 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. |
| |
| template <class Chunk> |
| FreeList<Chunk>::FreeList() : |
| _head(NULL), _tail(NULL) |
| #ifdef ASSERT |
| , _protecting_lock(NULL) |
| #endif |
| { |
| _size = 0; |
| _count = 0; |
| } |
| |
| template <class Chunk> |
| void FreeList<Chunk>::link_head(Chunk* v) { |
| assert_proper_lock_protection(); |
| set_head(v); |
| // If this method is not used (just set the head instead), |
| // this check can be avoided. |
| if (v != NULL) { |
| v->link_prev(NULL); |
| } |
| } |
| |
| |
| |
| template <class Chunk> |
| void FreeList<Chunk>::reset() { |
| // Don't set the _size to 0 because this method is |
| // used with a existing list that has a size but which has |
| // been emptied. |
| // Don't clear the _protecting_lock of an existing list. |
| set_count(0); |
| set_head(NULL); |
| set_tail(NULL); |
| } |
| |
| template <class Chunk> |
| void FreeList<Chunk>::initialize() { |
| #ifdef ASSERT |
| // Needed early because it might be checked in other initializing code. |
| set_protecting_lock(NULL); |
| #endif |
| reset(); |
| set_size(0); |
| } |
| |
| template <class Chunk_t> |
| Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() { |
| assert_proper_lock_protection(); |
| assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
| assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
| Chunk_t* fc = head(); |
| if (fc != NULL) { |
| Chunk_t* nextFC = fc->next(); |
| if (nextFC != NULL) { |
| // The chunk fc being removed has a "next". Set the "next" to the |
| // "prev" of fc. |
| nextFC->link_prev(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; |
| } |
| |
| |
| template <class Chunk> |
| void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) { |
| assert_proper_lock_protection(); |
| assert(fl->count() == 0, "Precondition"); |
| if (count() > 0) { |
| int k = 1; |
| fl->set_head(head()); n--; |
| Chunk* 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. |
| Chunk* new_head = tl->next(); |
| set_head(new_head); |
| set_count(count() - k); |
| if (new_head == NULL) { |
| set_tail(NULL); |
| } else { |
| new_head->link_prev(NULL); |
| } |
| // Now we can fix up the tail. |
| tl->link_next(NULL); |
| // And return the result. |
| fl->set_tail(tl); |
| fl->set_count(k); |
| } |
| } |
| |
| // Remove this chunk from the list |
| template <class Chunk> |
| void FreeList<Chunk>::remove_chunk(Chunk*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"); |
| |
| Chunk* prevFC = fc->prev(); |
| Chunk* nextFC = fc->next(); |
| if (nextFC != NULL) { |
| // The chunk fc being removed has a "next". Set the "next" to the |
| // "prev" of fc. |
| nextFC->link_prev(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->link_next(nextFC); |
| assert(tail() != prevFC || prevFC->next() == NULL, |
| "Next of tail should be NULL"); |
| } |
| decrement_count(); |
| assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0, |
| "H/T/C Inconsistency"); |
| // clear next and prev fields of fc, debug only |
| NOT_PRODUCT( |
| fc->link_prev(NULL); |
| fc->link_next(NULL); |
| ) |
| assert(fc->is_free(), "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. |
| template <class Chunk> |
| void FreeList<Chunk>::return_chunk_at_head(Chunk* 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"); |
| |
| Chunk* oldHead = head(); |
| assert(chunk != oldHead, "double insertion"); |
| chunk->link_after(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 |
| 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"); |
| } |
| |
| template <class Chunk> |
| void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) { |
| assert_proper_lock_protection(); |
| return_chunk_at_head(chunk, true); |
| } |
| |
| // Add this chunk at the tail of the list. |
| template <class Chunk> |
| void FreeList<Chunk>::return_chunk_at_tail(Chunk* 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"); |
| |
| Chunk* oldTail = tail(); |
| assert(chunk != oldTail, "double insertion"); |
| if (oldTail != NULL) { |
| oldTail->link_after(chunk); |
| } else { // only chunk in list |
| assert(head() == NULL, "inconsistent FreeList"); |
| link_head(chunk); |
| } |
| link_tail(chunk); |
| increment_count(); // of # of chunks in list |
| 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"); |
| } |
| |
| template <class Chunk> |
| void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) { |
| return_chunk_at_tail(chunk, true); |
| } |
| |
| template <class Chunk> |
| void FreeList<Chunk>::prepend(FreeList<Chunk>* 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. |
| Chunk* fl_tail = fl->tail(); |
| Chunk* this_head = head(); |
| assert(fl_tail->next() == NULL, "Well-formedness of fl"); |
| fl_tail->link_next(this_head); |
| this_head->link_prev(fl_tail); |
| set_head(fl->head()); |
| set_count(count() + fl->count()); |
| } |
| fl->set_head(NULL); |
| fl->set_tail(NULL); |
| fl->set_count(0); |
| } |
| } |
| |
| // verify_chunk_in_free_lists() is used to verify that an item is in this free list. |
| // It is used as a debugging aid. |
| template <class Chunk> |
| bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* 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"); |
| Chunk* 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; |
| } |
| |
| #ifdef ASSERT |
| template <class Chunk> |
| void FreeList<Chunk>::assert_proper_lock_protection_work() const { |
| // Nothing to do if the list has no assigned protecting lock |
| if (protecting_lock() == NULL) { |
| return; |
| } |
| |
| Thread* thr = Thread::current(); |
| if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) { |
| // assert that we are holding the freelist lock |
| } else if (thr->is_GC_task_thread()) { |
| assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED"); |
| } else if (thr->is_Java_thread()) { |
| assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing"); |
| } else { |
| ShouldNotReachHere(); // unaccounted thread type? |
| } |
| } |
| #endif |
| |
| // Print the "label line" for free list stats. |
| template <class Chunk> |
| void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) { |
| st->print("%16s\t", c); |
| st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" |
| "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n", |
| "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep", |
| "count", "cBirths", "cDeaths", "sBirths", "sDeaths"); |
| } |
| |
| // Print the AllocationStats for the given free list. If the second argument |
| // to the call is a non-null string, it is printed in the first column; |
| // otherwise, if the argument is null (the default), then the size of the |
| // (free list) block is printed in the first column. |
| template <class Chunk_t> |
| void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const { |
| if (c != NULL) { |
| st->print("%16s", c); |
| } else { |
| st->print(SIZE_FORMAT_W(16), size()); |
| } |
| } |
| |
| template class FreeList<Metablock>; |
| template class FreeList<Metachunk>; |
| #if INCLUDE_ALL_GCS |
| template class FreeList<FreeChunk>; |
| #endif // INCLUDE_ALL_GCS |