/*
* Copyright (c) 2010, 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
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*/
#include "precompiled.hpp"
#include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp"
#include "gc_implementation/concurrentMarkSweep/promotionInfo.hpp"
#include "oops/markOop.inline.hpp"
#include "oops/oop.inline.hpp"
/////////////////////////////////////////////////////////////////////////
//// PromotionInfo
/////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////
// We go over the list of promoted objects, removing each from the list,
// and applying the closure (this may, in turn, add more elements to
// the tail of the promoted list, and these newly added objects will
// also be processed) until the list is empty.
// To aid verification and debugging, in the non-product builds
// we actually forward _promoHead each time we process a promoted oop.
// Note that this is not necessary in general (i.e. when we don't need to
// call PromotionInfo::verify()) because oop_iterate can only add to the
// end of _promoTail, and never needs to look at _promoHead.
#define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \
\
void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \
NOT_PRODUCT(verify()); \
PromotedObject *curObj, *nextObj; \
for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \
if ((nextObj = curObj->next()) == NULL) { \
/* protect ourselves against additions due to closure application \
below by resetting the list. */ \
assert(_promoTail == curObj, "Should have been the tail"); \
_promoHead = _promoTail = NULL; \
} \
if (curObj->hasDisplacedMark()) { \
/* restore displaced header */ \
oop(curObj)->set_mark(nextDisplacedHeader()); \
} else { \
/* restore prototypical header */ \
oop(curObj)->init_mark(); \
} \
/* The "promoted_mark" should now not be set */ \
assert(!curObj->hasPromotedMark(), \
"Should have been cleared by restoring displaced mark-word"); \
NOT_PRODUCT(_promoHead = nextObj); \
if (cl != NULL) oop(curObj)->oop_iterate(cl); \
if (nextObj == NULL) { /* start at head of list reset above */ \
nextObj = _promoHead; \
} \
} \
assert(noPromotions(), "post-condition violation"); \
assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\
assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \
assert(_firstIndex == _nextIndex, "empty buffer"); \
}
// This should have been ALL_SINCE_...() just like the others,
// but, because the body of the method above is somehwat longer,
// the MSVC compiler cannot cope; as a workaround, we split the
// macro into its 3 constituent parts below (see original macro
// definition in specializedOopClosures.hpp).
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN)
PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v)
// Return the next displaced header, incrementing the pointer and
// recycling spool area as necessary.
markOop PromotionInfo::nextDisplacedHeader() {
assert(_spoolHead != NULL, "promotionInfo inconsistency");
assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex,
"Empty spool space: no displaced header can be fetched");
assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?");
markOop hdr = _spoolHead->displacedHdr[_firstIndex];
// Spool forward
if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block
// forward to next block, recycling this block into spare spool buffer
SpoolBlock* tmp = _spoolHead->nextSpoolBlock;
assert(_spoolHead != _spoolTail, "Spooling storage mix-up");
_spoolHead->nextSpoolBlock = _spareSpool;
_spareSpool = _spoolHead;
_spoolHead = tmp;
_firstIndex = 1;
NOT_PRODUCT(
if (_spoolHead == NULL) { // all buffers fully consumed
assert(_spoolTail == NULL && _nextIndex == 1,
"spool buffers processing inconsistency");
}
)
}
return hdr;
}
void PromotionInfo::track(PromotedObject* trackOop) {
track(trackOop, oop(trackOop)->klass());
}
void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) {
// make a copy of header as it may need to be spooled
markOop mark = oop(trackOop)->mark();
trackOop->clear_next();
if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
// save non-prototypical header, and mark oop
saveDisplacedHeader(mark);
trackOop->setDisplacedMark();
} else {
// we'd like to assert something like the following:
// assert(mark == markOopDesc::prototype(), "consistency check");
// ... but the above won't work because the age bits have not (yet) been
// cleared. The remainder of the check would be identical to the
// condition checked in must_be_preserved() above, so we don't really
// have anything useful to check here!
}
if (_promoTail != NULL) {
assert(_promoHead != NULL, "List consistency");
_promoTail->setNext(trackOop);
_promoTail = trackOop;
} else {
assert(_promoHead == NULL, "List consistency");
_promoHead = _promoTail = trackOop;
}
// Mask as newly promoted, so we can skip over such objects
// when scanning dirty cards
assert(!trackOop->hasPromotedMark(), "Should not have been marked");
trackOop->setPromotedMark();
}
// Save the given displaced header, incrementing the pointer and
// obtaining more spool area as necessary.
void PromotionInfo::saveDisplacedHeader(markOop hdr) {
assert(_spoolHead != NULL && _spoolTail != NULL,
"promotionInfo inconsistency");
assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
_spoolTail->displacedHdr[_nextIndex] = hdr;
// Spool forward
if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
// get a new spooling block
assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
_splice_point = _spoolTail; // save for splicing
_spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
_spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
// ... but will attempt filling before next promotion attempt
_nextIndex = 1;
}
}
// Ensure that spooling space exists. Return false if spooling space
// could not be obtained.
bool PromotionInfo::ensure_spooling_space_work() {
assert(!has_spooling_space(), "Only call when there is no spooling space");
// Try and obtain more spooling space
SpoolBlock* newSpool = getSpoolBlock();
assert(newSpool == NULL ||
(newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
"getSpoolBlock() sanity check");
if (newSpool == NULL) {
return false;
}
_nextIndex = 1;
if (_spoolTail == NULL) {
_spoolTail = newSpool;
if (_spoolHead == NULL) {
_spoolHead = newSpool;
_firstIndex = 1;
} else {
assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
"Splice point invariant");
// Extra check that _splice_point is connected to list
#ifdef ASSERT
{
SpoolBlock* blk = _spoolHead;
for (; blk->nextSpoolBlock != NULL;
blk = blk->nextSpoolBlock);
assert(blk != NULL && blk == _splice_point,
"Splice point incorrect");
}
#endif // ASSERT
_splice_point->nextSpoolBlock = newSpool;
}
} else {
assert(_spoolHead != NULL, "spool list consistency");
_spoolTail->nextSpoolBlock = newSpool;
_spoolTail = newSpool;
}
return true;
}
// Get a free spool buffer from the free pool, getting a new block
// from the heap if necessary.
SpoolBlock* PromotionInfo::getSpoolBlock() {
SpoolBlock* res;
if ((res = _spareSpool) != NULL) {
_spareSpool = _spareSpool->nextSpoolBlock;
res->nextSpoolBlock = NULL;
} else { // spare spool exhausted, get some from heap
res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
if (res != NULL) {
res->init();
}
}
assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
return res;
}
void PromotionInfo::startTrackingPromotions() {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = true;
}
#define CMSPrintPromoBlockInfo 1
void PromotionInfo::stopTrackingPromotions(uint worker_id) {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = false;
if (CMSPrintPromoBlockInfo > 1) {
print_statistics(worker_id);
}
}
void PromotionInfo::print_statistics(uint worker_id) const {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"Else will undercount");
assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
// Count the number of blocks and slots in the free pool
size_t slots = 0;
size_t blocks = 0;
for (SpoolBlock* cur_spool = _spareSpool;
cur_spool != NULL;
cur_spool = cur_spool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
assert((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
"first entry of displacedHdr should be self-referential");
slots += cur_spool->bufferSize - 1;
blocks++;
}
if (_spoolHead != NULL) {
slots += _spoolHead->bufferSize - 1;
blocks++;
}
gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ",
worker_id, blocks, slots);
}
// When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
// points to the next slot available for filling.
// The set of slots holding displaced headers are then all those in the
// right-open interval denoted by:
//
// [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
//
// When _spoolTail is NULL, then the set of slots with displaced headers
// is all those starting at the slot <_spoolHead, _firstIndex> and
// going up to the last slot of last block in the linked list.
// In this lartter case, _splice_point points to the tail block of
// this linked list of blocks holding displaced headers.
void PromotionInfo::verify() const {
// Verify the following:
// 1. the number of displaced headers matches the number of promoted
// objects that have displaced headers
// 2. each promoted object lies in this space
debug_only(
PromotedObject* junk = NULL;
assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
"Offset of PromotedObject::_next is expected to align with "
" the OopDesc::_mark within OopDesc");
)
// FIXME: guarantee????
guarantee(_spoolHead == NULL || _spoolTail != NULL ||
_splice_point != NULL, "list consistency");
guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
// count the number of objects with displaced headers
size_t numObjsWithDisplacedHdrs = 0;
for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
// the last promoted object may fail the mark() != NULL test of is_oop().
guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
if (curObj->hasDisplacedMark()) {
numObjsWithDisplacedHdrs++;
}
}
// Count the number of displaced headers
size_t numDisplacedHdrs = 0;
for (SpoolBlock* curSpool = _spoolHead;
curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
"first entry of displacedHdr should be self-referential");
numDisplacedHdrs += curSpool->bufferSize - 1;
}
guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
"internal consistency");
guarantee(_spoolTail != NULL || _nextIndex == 1,
"Inconsistency between _spoolTail and _nextIndex");
// We overcounted (_firstIndex-1) worth of slots in block
// _spoolHead and we undercounted (_nextIndex-1) worth of
// slots in block _spoolTail. We make an appropriate
// adjustment by subtracting the first and adding the
// second: - (_firstIndex - 1) + (_nextIndex - 1)
numDisplacedHdrs += (_nextIndex - _firstIndex);
guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
}
void PromotionInfo::print_on(outputStream* st) const {
SpoolBlock* curSpool = NULL;
size_t i = 0;
st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
_firstIndex, _nextIndex);
for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" active ");
i++;
}
for (curSpool = _spoolTail; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" inactive ");
i++;
}
for (curSpool = _spareSpool; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" free ");
i++;
}
st->print_cr(" " SIZE_FORMAT " header spooling blocks", i);
}
void SpoolBlock::print_on(outputStream* st) const {
st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
this, (HeapWord*)displacedHdr + bufferSize,
bufferSize, nextSpoolBlock);
}