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 /*

  * Copyright (c) 2001, 2011, 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

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/collectionSetChooser.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1CollectorPolicy.hpp"

 #include "gc_implementation/g1/g1ErgoVerbose.hpp"

 #include "memory/space.inline.hpp"

 CSetChooserCache::CSetChooserCache() {

   for (int i = 0; i < CacheLength; ++i)

     _cache[i] = NULL;

   clear();

 }

 void CSetChooserCache::clear() {

   _occupancy = 0;

   _first = 0;

   for (int i = 0; i < CacheLength; ++i) {

     HeapRegion *hr = _cache[i];

     if (hr != NULL)

       hr->set_sort_index(-1);

     _cache[i] = NULL;

   }

 }

 #ifndef PRODUCT

 bool CSetChooserCache::verify() {

   int index = _first;

   HeapRegion *prev = NULL;

   for (int i = 0; i < _occupancy; ++i) {

     guarantee(_cache[index] != NULL, "cache entry should not be empty");

     HeapRegion *hr = _cache[index];

     guarantee(!hr->is_young(), "should not be young!");

     if (prev != NULL) {

       guarantee(prev->gc_efficiency() >= hr->gc_efficiency(),

                 "cache should be correctly ordered");

     }

     guarantee(hr->sort_index() == get_sort_index(index),

               "sort index should be correct");

     index = trim_index(index + 1);

     prev = hr;

   }

   for (int i = 0; i < (CacheLength - _occupancy); ++i) {

     guarantee(_cache[index] == NULL, "cache entry should be empty");

     index = trim_index(index + 1);

   }

   guarantee(index == _first, "we should have reached where we started from");

   return true;

 }

 #endif // PRODUCT

 void CSetChooserCache::insert(HeapRegion *hr) {

   assert(!is_full(), "cache should not be empty");

   hr->calc_gc_efficiency();

   int empty_index;

   if (_occupancy == 0) {

     empty_index = _first;

   } else {

     empty_index = trim_index(_first + _occupancy);

     assert(_cache[empty_index] == NULL, "last slot should be empty");

     int last_index = trim_index(empty_index - 1);

     HeapRegion *last = _cache[last_index];

     assert(last != NULL,"as the cache is not empty, last should not be empty");

     while (empty_index != _first &&

            last->gc_efficiency() < hr->gc_efficiency()) {

       _cache[empty_index] = last;

       last->set_sort_index(get_sort_index(empty_index));

       empty_index = last_index;

       last_index = trim_index(last_index - 1);

       last = _cache[last_index];

     }

   }

   _cache[empty_index] = hr;

   hr->set_sort_index(get_sort_index(empty_index));

   ++_occupancy;

   assert(verify(), "cache should be consistent");

 }

 HeapRegion *CSetChooserCache::remove_first() {

   if (_occupancy > 0) {

     assert(_cache[_first] != NULL, "cache should have at least one region");

     HeapRegion *ret = _cache[_first];

     _cache[_first] = NULL;

     ret->set_sort_index(-1);

     --_occupancy;

     _first = trim_index(_first + 1);

     assert(verify(), "cache should be consistent");

     return ret;

   } else {

     return NULL;

   }

 }

 static inline int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {

   if (hr1 == NULL) {

     if (hr2 == NULL) return 0;

     else return 1;

   } else if (hr2 == NULL) {

     return -1;

   }

   if (hr2->gc_efficiency() < hr1->gc_efficiency()) return -1;

   else if (hr1->gc_efficiency() < hr2->gc_efficiency()) return 1;

   else return 0;

 }

 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {

   return orderRegions(*hr1p, *hr2p);

 }

 CollectionSetChooser::CollectionSetChooser() :

   // The line below is the worst bit of C++ hackery I've ever written

   // (Detlefs, 11/23).  You should think of it as equivalent to

   // "_regions(100, true)": initialize the growable array and inform it

   // that it should allocate its elem array(s) on the C heap.

   //

   // The first argument, however, is actually a comma expression

   // (set_allocation_type(this, C_HEAP), 100). The purpose of the

   // set_allocation_type() call is to replace the default allocation

   // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will

   // allow to pass the assert in GenericGrowableArray() which checks

   // that a growable array object must be on C heap if elements are.

   //

   // Note: containing object is allocated on C heap since it is CHeapObj.

   //

   _markedRegions((ResourceObj::set_allocation_type((address)&_markedRegions,

                                              ResourceObj::C_HEAP),

                   100),

                  true),

   _curMarkedIndex(0),

   _numMarkedRegions(0),

   _unmarked_age_1_returned_as_new(false),

   _first_par_unreserved_idx(0)

 {}

 #ifndef PRODUCT

 bool CollectionSetChooser::verify() {

   int index = 0;

   guarantee(_curMarkedIndex <= _numMarkedRegions,

             "_curMarkedIndex should be within bounds");

   while (index < _curMarkedIndex) {

     guarantee(_markedRegions.at(index++) == NULL,

               "all entries before _curMarkedIndex should be NULL");

   }

   HeapRegion *prev = NULL;

   while (index < _numMarkedRegions) {

     HeapRegion *curr = _markedRegions.at(index++);

     guarantee(curr != NULL, "Regions in _markedRegions array cannot be NULL");

     int si = curr->sort_index();

     guarantee(!curr->is_young(), "should not be young!");

     guarantee(si > -1 && si == (index-1), "sort index invariant");

     if (prev != NULL) {

       guarantee(orderRegions(prev, curr) != 1, "regions should be sorted");

     }

     prev = curr;

   }

   return _cache.verify();

 }

 #endif

 void

 CollectionSetChooser::fillCache() {

   while (!_cache.is_full() && (_curMarkedIndex < _numMarkedRegions)) {

     HeapRegion* hr = _markedRegions.at(_curMarkedIndex);

     assert(hr != NULL,

            err_msg("Unexpected NULL hr in _markedRegions at index %d",

                    _curMarkedIndex));

     _curMarkedIndex += 1;

     assert(!hr->is_young(), "should not be young!");

     assert(hr->sort_index() == _curMarkedIndex-1, "sort_index invariant");

     _markedRegions.at_put(hr->sort_index(), NULL);

     _cache.insert(hr);

     assert(!_cache.is_empty(), "cache should not be empty");

   }

   assert(verify(), "cache should be consistent");

 }

 void

 CollectionSetChooser::sortMarkedHeapRegions() {

   guarantee(_cache.is_empty(), "cache should be empty");

   // First trim any unused portion of the top in the parallel case.

   if (_first_par_unreserved_idx > 0) {

     if (G1PrintParCleanupStats) {

       gclog_or_tty->print("     Truncating _markedRegions from %d to %d.\n",

                           _markedRegions.length(), _first_par_unreserved_idx);

     }

     assert(_first_par_unreserved_idx <= _markedRegions.length(),

            "Or we didn't reserved enough length");

     _markedRegions.trunc_to(_first_par_unreserved_idx);

   }

   _markedRegions.sort(orderRegions);

   assert(_numMarkedRegions <= _markedRegions.length(), "Requirement");

   assert(_numMarkedRegions == 0

          || _markedRegions.at(_numMarkedRegions-1) != NULL,

          "Testing _numMarkedRegions");

   assert(_numMarkedRegions == _markedRegions.length()

          || _markedRegions.at(_numMarkedRegions) == NULL,

          "Testing _numMarkedRegions");

   if (G1PrintParCleanupStats) {

     gclog_or_tty->print_cr("     Sorted %d marked regions.", _numMarkedRegions);

   }

   for (int i = 0; i < _numMarkedRegions; i++) {

     assert(_markedRegions.at(i) != NULL, "Should be true by sorting!");

     _markedRegions.at(i)->set_sort_index(i);

   }

   if (G1PrintRegionLivenessInfo) {

     G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Sorting");

     for (int i = 0; i < _numMarkedRegions; ++i) {

       HeapRegion* r = _markedRegions.at(i);

       cl.doHeapRegion(r);

     }

   }

   assert(verify(), "should now be sorted");

 }

 void

 CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {

   assert(!hr->isHumongous(),

          "Humongous regions shouldn't be added to the collection set");

   assert(!hr->is_young(), "should not be young!");

   _markedRegions.append(hr);

   _numMarkedRegions++;

   hr->calc_gc_efficiency();

 }

 void

 CollectionSetChooser::

 prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize) {

   _first_par_unreserved_idx = 0;

   size_t max_waste = ParallelGCThreads * chunkSize;

   // it should be aligned with respect to chunkSize

   size_t aligned_n_regions =

                      (n_regions + (chunkSize - 1)) / chunkSize * chunkSize;

   assert( aligned_n_regions % chunkSize == 0, "should be aligned" );

   _markedRegions.at_put_grow((int)(aligned_n_regions + max_waste - 1), NULL);

 }

 jint

 CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {

   jint res = Atomic::add(n_regions, &_first_par_unreserved_idx);

   assert(_markedRegions.length() > res + n_regions - 1,

          "Should already have been expanded");

   return res - n_regions;

 }

 void

 CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {

   assert(_markedRegions.at(index) == NULL, "precondition");

   assert(!hr->is_young(), "should not be young!");

   _markedRegions.at_put(index, hr);

   hr->calc_gc_efficiency();

 }

 void

 CollectionSetChooser::incNumMarkedHeapRegions(jint inc_by) {

   (void)Atomic::add(inc_by, &_numMarkedRegions);

 }

 void

 CollectionSetChooser::clearMarkedHeapRegions(){

   for (int i = 0; i < _markedRegions.length(); i++) {

     HeapRegion* r =   _markedRegions.at(i);

     if (r != NULL) r->set_sort_index(-1);

   }

   _markedRegions.clear();

   _curMarkedIndex = 0;

   _numMarkedRegions = 0;

   _cache.clear();

 };

 void

 CollectionSetChooser::updateAfterFullCollection() {

   clearMarkedHeapRegions();

 }

 // if time_remaining < 0.0, then this method should try to return

 // a region, whether it fits within the remaining time or not

 HeapRegion*

 CollectionSetChooser::getNextMarkedRegion(double time_remaining,

                                           double avg_prediction) {

   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   G1CollectorPolicy* g1p = g1h->g1_policy();

   fillCache();

   if (_cache.is_empty()) {

     assert(_curMarkedIndex == _numMarkedRegions,

            "if cache is empty, list should also be empty");

     ergo_verbose0(ErgoCSetConstruction,

                   "stop adding old regions to CSet",

                   ergo_format_reason("cache is empty"));

     return NULL;

   }

   HeapRegion *hr = _cache.get_first();

   assert(hr != NULL, "if cache not empty, first entry should be non-null");

   double predicted_time = g1h->predict_region_elapsed_time_ms(hr, false);

   if (g1p->adaptive_young_list_length()) {

     if (time_remaining - predicted_time < 0.0) {

       g1h->check_if_region_is_too_expensive(predicted_time);

       ergo_verbose2(ErgoCSetConstruction,

                     "stop adding old regions to CSet",

                     ergo_format_reason("predicted old region time higher than remaining time")

                     ergo_format_ms("predicted old region time")

                     ergo_format_ms("remaining time"),

                     predicted_time, time_remaining);

       return NULL;

     }

   } else {

     double threshold = 2.0 * avg_prediction;

     if (predicted_time > threshold) {

       ergo_verbose2(ErgoCSetConstruction,

                     "stop adding old regions to CSet",

                     ergo_format_reason("predicted old region time higher than threshold")

                     ergo_format_ms("predicted old region time")

                     ergo_format_ms("threshold"),

                     predicted_time, threshold);

       return NULL;

     }

   }

   HeapRegion *hr2 = _cache.remove_first();

   assert(hr == hr2, "cache contents should not have changed");

   return hr;

 }