duke@435: /*
stefank@2314:  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp"
stefank@2314: #include "gc_implementation/concurrentMarkSweep/freeList.hpp"
stefank@2314: #include "memory/sharedHeap.hpp"
stefank@2314: #include "runtime/globals.hpp"
stefank@2314: #include "runtime/mutex.hpp"
stefank@2314: #include "runtime/vmThread.hpp"
duke@435: 
duke@435: // Free list.  A FreeList is used to access a linked list of chunks
duke@435: // of space in the heap.  The head and tail are maintained so that
duke@435: // items can be (as in the current implementation) added at the
duke@435: // at the tail of the list and removed from the head of the list to
duke@435: // maintain a FIFO queue.
duke@435: 
duke@435: FreeList::FreeList() :
duke@435:   _head(NULL), _tail(NULL)
duke@435: #ifdef ASSERT
duke@435:   , _protecting_lock(NULL)
duke@435: #endif
duke@435: {
duke@435:   _size         = 0;
duke@435:   _count        = 0;
duke@435:   _hint         = 0;
duke@435:   init_statistics();
duke@435: }
duke@435: 
duke@435: FreeList::FreeList(FreeChunk* fc) :
duke@435:   _head(fc), _tail(fc)
duke@435: #ifdef ASSERT
duke@435:   , _protecting_lock(NULL)
duke@435: #endif
duke@435: {
duke@435:   _size         = fc->size();
duke@435:   _count        = 1;
duke@435:   _hint         = 0;
duke@435:   init_statistics();
duke@435: #ifndef PRODUCT
duke@435:   _allocation_stats.set_returnedBytes(size() * HeapWordSize);
duke@435: #endif
duke@435: }
duke@435: 
duke@435: FreeList::FreeList(HeapWord* addr, size_t size) :
duke@435:   _head((FreeChunk*) addr), _tail((FreeChunk*) addr)
duke@435: #ifdef ASSERT
duke@435:   , _protecting_lock(NULL)
duke@435: #endif
duke@435: {
duke@435:   assert(size > sizeof(FreeChunk), "size is too small");
duke@435:   head()->setSize(size);
duke@435:   _size         = size;
duke@435:   _count        = 1;
duke@435:   init_statistics();
duke@435: #ifndef PRODUCT
duke@435:   _allocation_stats.set_returnedBytes(_size * HeapWordSize);
duke@435: #endif
duke@435: }
duke@435: 
duke@435: void FreeList::reset(size_t hint) {
duke@435:   set_count(0);
duke@435:   set_head(NULL);
duke@435:   set_tail(NULL);
duke@435:   set_hint(hint);
duke@435: }
duke@435: 
ysr@1580: void FreeList::init_statistics(bool split_birth) {
ysr@1580:   _allocation_stats.initialize(split_birth);
duke@435: }
duke@435: 
duke@435: FreeChunk* FreeList::getChunkAtHead() {
duke@435:   assert_proper_lock_protection();
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:   FreeChunk* fc = head();
duke@435:   if (fc != NULL) {
duke@435:     FreeChunk* nextFC = fc->next();
duke@435:     if (nextFC != NULL) {
duke@435:       // The chunk fc being removed has a "next".  Set the "next" to the
duke@435:       // "prev" of fc.
duke@435:       nextFC->linkPrev(NULL);
duke@435:     } else { // removed tail of list
duke@435:       link_tail(NULL);
duke@435:     }
duke@435:     link_head(nextFC);
duke@435:     decrement_count();
duke@435:   }
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:   return fc;
duke@435: }
duke@435: 
duke@435: 
duke@435: void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
duke@435:   assert_proper_lock_protection();
duke@435:   assert(fl->count() == 0, "Precondition");
duke@435:   if (count() > 0) {
duke@435:     int k = 1;
duke@435:     fl->set_head(head()); n--;
duke@435:     FreeChunk* tl = head();
duke@435:     while (tl->next() != NULL && n > 0) {
duke@435:       tl = tl->next(); n--; k++;
duke@435:     }
duke@435:     assert(tl != NULL, "Loop Inv.");
duke@435: 
duke@435:     // First, fix up the list we took from.
duke@435:     FreeChunk* new_head = tl->next();
duke@435:     set_head(new_head);
duke@435:     set_count(count() - k);
duke@435:     if (new_head == NULL) {
duke@435:       set_tail(NULL);
duke@435:     } else {
duke@435:       new_head->linkPrev(NULL);
duke@435:     }
duke@435:     // Now we can fix up the tail.
duke@435:     tl->linkNext(NULL);
duke@435:     // And return the result.
duke@435:     fl->set_tail(tl);
duke@435:     fl->set_count(k);
duke@435:   }
duke@435: }
duke@435: 
duke@435: // Remove this chunk from the list
duke@435: void FreeList::removeChunk(FreeChunk*fc) {
duke@435:    assert_proper_lock_protection();
duke@435:    assert(head() != NULL, "Remove from empty list");
duke@435:    assert(fc != NULL, "Remove a NULL chunk");
duke@435:    assert(size() == fc->size(), "Wrong list");
duke@435:    assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:    assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435: 
duke@435:    FreeChunk* prevFC = fc->prev();
duke@435:    FreeChunk* nextFC = fc->next();
duke@435:    if (nextFC != NULL) {
duke@435:      // The chunk fc being removed has a "next".  Set the "next" to the
duke@435:      // "prev" of fc.
duke@435:      nextFC->linkPrev(prevFC);
duke@435:    } else { // removed tail of list
duke@435:      link_tail(prevFC);
duke@435:    }
duke@435:    if (prevFC == NULL) { // removed head of list
duke@435:      link_head(nextFC);
duke@435:      assert(nextFC == NULL || nextFC->prev() == NULL,
duke@435:        "Prev of head should be NULL");
duke@435:    } else {
duke@435:      prevFC->linkNext(nextFC);
duke@435:      assert(tail() != prevFC || prevFC->next() == NULL,
duke@435:        "Next of tail should be NULL");
duke@435:    }
duke@435:    decrement_count();
ysr@2132:    assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0,
ysr@2132:           "H/T/C Inconsistency");
duke@435:    // clear next and prev fields of fc, debug only
duke@435:    NOT_PRODUCT(
duke@435:      fc->linkPrev(NULL);
duke@435:      fc->linkNext(NULL);
duke@435:    )
duke@435:    assert(fc->isFree(), "Should still be a free chunk");
duke@435:    assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:    assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:    assert(head() == NULL || head()->size() == size(), "wrong item on list");
duke@435:    assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
duke@435: }
duke@435: 
duke@435: // Add this chunk at the head of the list.
duke@435: void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
duke@435:   assert_proper_lock_protection();
duke@435:   assert(chunk != NULL, "insert a NULL chunk");
duke@435:   assert(size() == chunk->size(), "Wrong size");
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435: 
duke@435:   FreeChunk* oldHead = head();
duke@435:   assert(chunk != oldHead, "double insertion");
duke@435:   chunk->linkAfter(oldHead);
duke@435:   link_head(chunk);
duke@435:   if (oldHead == NULL) { // only chunk in list
duke@435:     assert(tail() == NULL, "inconsistent FreeList");
duke@435:     link_tail(chunk);
duke@435:   }
duke@435:   increment_count(); // of # of chunks in list
duke@435:   DEBUG_ONLY(
duke@435:     if (record_return) {
duke@435:       increment_returnedBytes_by(size()*HeapWordSize);
duke@435:     }
duke@435:   )
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:   assert(head() == NULL || head()->size() == size(), "wrong item on list");
duke@435:   assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
duke@435: }
duke@435: 
duke@435: void FreeList::returnChunkAtHead(FreeChunk* chunk) {
duke@435:   assert_proper_lock_protection();
duke@435:   returnChunkAtHead(chunk, true);
duke@435: }
duke@435: 
duke@435: // Add this chunk at the tail of the list.
duke@435: void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
duke@435:   assert_proper_lock_protection();
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:   assert(chunk != NULL, "insert a NULL chunk");
duke@435:   assert(size() == chunk->size(), "wrong size");
duke@435: 
duke@435:   FreeChunk* oldTail = tail();
duke@435:   assert(chunk != oldTail, "double insertion");
duke@435:   if (oldTail != NULL) {
duke@435:     oldTail->linkAfter(chunk);
duke@435:   } else { // only chunk in list
duke@435:     assert(head() == NULL, "inconsistent FreeList");
duke@435:     link_head(chunk);
duke@435:   }
duke@435:   link_tail(chunk);
duke@435:   increment_count();  // of # of chunks in list
duke@435:   DEBUG_ONLY(
duke@435:     if (record_return) {
duke@435:       increment_returnedBytes_by(size()*HeapWordSize);
duke@435:     }
duke@435:   )
duke@435:   assert(head() == NULL || head()->prev() == NULL, "list invariant");
duke@435:   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
duke@435:   assert(head() == NULL || head()->size() == size(), "wrong item on list");
duke@435:   assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
duke@435: }
duke@435: 
duke@435: void FreeList::returnChunkAtTail(FreeChunk* chunk) {
duke@435:   returnChunkAtTail(chunk, true);
duke@435: }
duke@435: 
duke@435: void FreeList::prepend(FreeList* fl) {
duke@435:   assert_proper_lock_protection();
duke@435:   if (fl->count() > 0) {
duke@435:     if (count() == 0) {
duke@435:       set_head(fl->head());
duke@435:       set_tail(fl->tail());
duke@435:       set_count(fl->count());
duke@435:     } else {
duke@435:       // Both are non-empty.
duke@435:       FreeChunk* fl_tail = fl->tail();
duke@435:       FreeChunk* this_head = head();
duke@435:       assert(fl_tail->next() == NULL, "Well-formedness of fl");
duke@435:       fl_tail->linkNext(this_head);
duke@435:       this_head->linkPrev(fl_tail);
duke@435:       set_head(fl->head());
duke@435:       set_count(count() + fl->count());
duke@435:     }
duke@435:     fl->set_head(NULL);
duke@435:     fl->set_tail(NULL);
duke@435:     fl->set_count(0);
duke@435:   }
duke@435: }
duke@435: 
duke@435: // verifyChunkInFreeLists() is used to verify that an item is in this free list.
duke@435: // It is used as a debugging aid.
duke@435: bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
duke@435:   // This is an internal consistency check, not part of the check that the
duke@435:   // chunk is in the free lists.
duke@435:   guarantee(fc->size() == size(), "Wrong list is being searched");
duke@435:   FreeChunk* curFC = head();
duke@435:   while (curFC) {
duke@435:     // This is an internal consistency check.
duke@435:     guarantee(size() == curFC->size(), "Chunk is in wrong list.");
duke@435:     if (fc == curFC) {
duke@435:       return true;
duke@435:     }
duke@435:     curFC = curFC->next();
duke@435:   }
duke@435:   return false;
duke@435: }
duke@435: 
duke@435: #ifndef PRODUCT
ysr@1580: void FreeList::verify_stats() const {
ysr@1580:   // The +1 of the LH comparand is to allow some "looseness" in
ysr@1580:   // checking: we usually call this interface when adding a block
ysr@1580:   // and we'll subsequently update the stats; we cannot update the
ysr@1580:   // stats beforehand because in the case of the large-block BT
ysr@1580:   // dictionary for example, this might be the first block and
ysr@1580:   // in that case there would be no place that we could record
ysr@1580:   // the stats (which are kept in the block itself).
ysr@1580:   assert(_allocation_stats.prevSweep() + _allocation_stats.splitBirths() + 1   // Total Stock + 1
ysr@1580:           >= _allocation_stats.splitDeaths() + (ssize_t)count(), "Conservation Principle");
ysr@1580: }
ysr@1580: 
duke@435: void FreeList::assert_proper_lock_protection_work() const {
ysr@1580:   assert(_protecting_lock != NULL, "Don't call this directly");
ysr@1580:   assert(ParallelGCThreads > 0, "Don't call this directly");
ysr@1580:   Thread* thr = Thread::current();
ysr@1580:   if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) {
ysr@1580:     // assert that we are holding the freelist lock
ysr@1580:   } else if (thr->is_GC_task_thread()) {
ysr@1580:     assert(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
ysr@1580:   } else if (thr->is_Java_thread()) {
ysr@1580:     assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing");
ysr@1580:   } else {
ysr@1580:     ShouldNotReachHere();  // unaccounted thread type?
duke@435:   }
duke@435: }
duke@435: #endif
ysr@447: 
ysr@447: // Print the "label line" for free list stats.
ysr@447: void FreeList::print_labels_on(outputStream* st, const char* c) {
ysr@447:   st->print("%16s\t", c);
ysr@447:   st->print("%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"
ysr@447:             "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "\n",
ysr@447:             "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep",
ysr@447:             "count",   "cBirths", "cDeaths", "sBirths", "sDeaths");
ysr@447: }
ysr@447: 
ysr@447: // Print the AllocationStats for the given free list. If the second argument
ysr@447: // to the call is a non-null string, it is printed in the first column;
ysr@447: // otherwise, if the argument is null (the default), then the size of the
ysr@447: // (free list) block is printed in the first column.
ysr@447: void FreeList::print_on(outputStream* st, const char* c) const {
ysr@447:   if (c != NULL) {
ysr@447:     st->print("%16s", c);
ysr@447:   } else {
ysr@447:     st->print(SIZE_FORMAT_W(16), size());
ysr@447:   }
ysr@447:   st->print("\t"
ysr@447:            SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t"
ysr@447:            SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\n",
ysr@447:            bfrSurp(),             surplus(),             desired(),             prevSweep(),           beforeSweep(),
ysr@447:            count(),               coalBirths(),          coalDeaths(),          splitBirths(),         splitDeaths());
ysr@447: }