/*

 * Copyright (c) 2001, 2014, 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_implementation/shared/parGCAllocBuffer.hpp"

#include "memory/sharedHeap.hpp"

#include "oops/arrayOop.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/globalDefinitions.hpp"

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

ParGCAllocBuffer::ParGCAllocBuffer(size_t desired_plab_sz_) :

  _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),

  _end(NULL), _hard_end(NULL),

  _retained(false), _retained_filler(),

  _allocated(0), _wasted(0)

{

  assert (min_size() > AlignmentReserve, "Inconsistency!");

  // arrayOopDesc::header_size depends on command line initialization.

  FillerHeaderSize = align_object_size(arrayOopDesc::header_size(T_INT));

  AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? FillerHeaderSize : 0;

}

size_t ParGCAllocBuffer::FillerHeaderSize;

// If the minimum object size is greater than MinObjAlignment, we can

// end up with a shard at the end of the buffer that's smaller than

// the smallest object.  We can't allow that because the buffer must

// look like it's full of objects when we retire it, so we make

// sure we have enough space for a filler int array object.

size_t ParGCAllocBuffer::AlignmentReserve;

void ParGCAllocBuffer::retire(bool end_of_gc, bool retain) {

  assert(!retain || end_of_gc, "Can only retain at GC end.");

  if (_retained) {

    // If the buffer had been retained shorten the previous filler object.

    assert(_retained_filler.end() <= _top, "INVARIANT");

    CollectedHeap::fill_with_object(_retained_filler);

    // Wasted space book-keeping, otherwise (normally) done in invalidate()

    _wasted += _retained_filler.word_size();

    _retained = false;

  }

  assert(!end_of_gc || !_retained, "At this point, end_of_gc ==> !_retained.");

  if (_top < _hard_end) {

    CollectedHeap::fill_with_object(_top, _hard_end);

    if (!retain) {

      invalidate();

    } else {

      // Is there wasted space we'd like to retain for the next GC?

      if (pointer_delta(_end, _top) > FillerHeaderSize) {

        _retained = true;

        _retained_filler = MemRegion(_top, FillerHeaderSize);

        _top = _top + FillerHeaderSize;

      } else {

        invalidate();

      }

    }

  }

}

void ParGCAllocBuffer::flush_stats(PLABStats* stats) {

  assert(ResizePLAB, "Wasted work");

  stats->add_allocated(_allocated);

  stats->add_wasted(_wasted);

  stats->add_unused(pointer_delta(_end, _top));

}

// Compute desired plab size and latch result for later

// use. This should be called once at the end of parallel

// scavenge; it clears the sensor accumulators.

void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) {

  assert(ResizePLAB, "Not set");

  assert(is_object_aligned(max_size()) && min_size() <= max_size(),

         "PLAB clipping computation may be incorrect");

  if (_allocated == 0) {

    assert(_unused == 0,

           err_msg("Inconsistency in PLAB stats: "

                   "_allocated: "SIZE_FORMAT", "

                   "_wasted: "SIZE_FORMAT", "

                   "_unused: "SIZE_FORMAT", "

                   "_used  : "SIZE_FORMAT,

                   _allocated, _wasted, _unused, _used));

    _allocated = 1;

  }

  double wasted_frac    = (double)_unused/(double)_allocated;

  size_t target_refills = (size_t)((wasted_frac*TargetSurvivorRatio)/

                                   TargetPLABWastePct);

  if (target_refills == 0) {

    target_refills = 1;

  }

  _used = _allocated - _wasted - _unused;

  size_t plab_sz = _used/(target_refills*no_of_gc_workers);

  if (PrintPLAB) gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT " ", plab_sz);

  // Take historical weighted average

  _filter.sample(plab_sz);

  // Clip from above and below, and align to object boundary

  plab_sz = MAX2(min_size(), (size_t)_filter.average());

  plab_sz = MIN2(max_size(), plab_sz);

  plab_sz = align_object_size(plab_sz);

  // Latch the result

  if (PrintPLAB) gclog_or_tty->print(" desired_plab_sz = " SIZE_FORMAT ") ", plab_sz);

  _desired_plab_sz = plab_sz;

  // Now clear the accumulators for next round:

  // note this needs to be fixed in the case where we

  // are retaining across scavenges. FIX ME !!! XXX

  _allocated = 0;

  _wasted    = 0;

  _unused    = 0;

}

#ifndef PRODUCT

void ParGCAllocBuffer::print() {

  gclog_or_tty->print("parGCAllocBuffer: _bottom: " PTR_FORMAT "  _top: " PTR_FORMAT

             "  _end: " PTR_FORMAT "  _hard_end: " PTR_FORMAT " _retained: %c"

             " _retained_filler: [" PTR_FORMAT "," PTR_FORMAT ")\n",

             _bottom, _top, _end, _hard_end,

             "FT"[_retained], _retained_filler.start(), _retained_filler.end());

}

#endif // !PRODUCT