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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * 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->clearNext();

   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);

 }