1 /*
   2  * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  26 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
  27 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
  28 #include "gc_implementation/shenandoah/shenandoahUtils.hpp"
  29 #include "runtime/atomic.hpp"
  30 #include "utilities/copy.hpp"
  31 
  32 ShenandoahHeapRegionSetIterator::ShenandoahHeapRegionSetIterator(const ShenandoahHeapRegionSet* const set) :
  33         _set(set), _heap(ShenandoahHeap::heap()), _current_index(0) {}
  34 
  35 void ShenandoahHeapRegionSetIterator::reset(const ShenandoahHeapRegionSet* const set) {
  36   _set = set;
  37   _current_index = 0;
  38 }
  39 
  40 ShenandoahHeapRegionSet::ShenandoahHeapRegionSet() :
  41         _heap(ShenandoahHeap::heap()),
  42         _map_size(_heap->num_regions()),
  43         _region_size_bytes_shift(ShenandoahHeapRegion::region_size_bytes_shift()),
  44         _set_map(NEW_C_HEAP_ARRAY(jbyte, _map_size, mtGC)),
  45         // Bias set map's base address for fast test if an oop is in set
  46         _biased_set_map(_set_map - ((uintx)_heap->base() >> _region_size_bytes_shift)),
  47         _region_count(0)
  48 {
  49   // Use 1-byte data type
  50   STATIC_ASSERT(sizeof(jbyte) == 1);
  51 
  52   // Initialize cset map
  53   Copy::zero_to_bytes(_set_map, _map_size);
  54 }
  55 
  56 ShenandoahHeapRegionSet::~ShenandoahHeapRegionSet() {
  57   FREE_C_HEAP_ARRAY(jbyte, _set_map, mtGC);
  58 }
  59 
  60 void ShenandoahHeapRegionSet::add_region(ShenandoahHeapRegion* r) {
  61   assert(!is_in(r), "Already in collection set");
  62   _set_map[r->index()] = 1;
  63   _region_count++;
  64 }
  65 
  66 bool ShenandoahHeapRegionSet::add_region_check_for_duplicates(ShenandoahHeapRegion* r) {
  67   if (!is_in(r)) {
  68     add_region(r);
  69     return true;
  70   } else {
  71     return false;
  72   }
  73 }
  74 
  75 void ShenandoahHeapRegionSet::remove_region(ShenandoahHeapRegion* r) {
  76   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  77   assert(Thread::current()->is_VM_thread(), "Must be VMThread");
  78   assert(is_in(r), "Not in region set");
  79   _set_map[r->index()] = 0;
  80   _region_count --;
  81 }
  82 
  83 void ShenandoahHeapRegionSet::clear() {
  84   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  85   Copy::zero_to_bytes(_set_map, _map_size);
  86 
  87   _region_count = 0;
  88 }
  89 
  90 ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::claim_next() {
  91   size_t num_regions = _heap->num_regions();
  92   if (_current_index >= (jint)num_regions) {
  93     return NULL;
  94   }
  95 
  96   jint saved_current = _current_index;
  97   size_t index = (size_t)saved_current;
  98 
  99   while(index < num_regions) {
 100     if (_set->is_in(index)) {
 101       jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);
 102       assert(cur >= (jint)saved_current, "Must move forward");
 103       if (cur == saved_current) {
 104         assert(_set->is_in(index), "Invariant");
 105         return _heap->get_region(index);
 106       } else {
 107         index = (size_t)cur;
 108         saved_current = cur;
 109       }
 110     } else {
 111       index ++;
 112     }
 113   }
 114   return NULL;
 115 }
 116 
 117 ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::next() {
 118   size_t num_regions = _heap->num_regions();
 119   for (size_t index = (size_t)_current_index; index < num_regions; index ++) {
 120     if (_set->is_in(index)) {
 121       _current_index = (jint)(index + 1);
 122       return _heap->get_region(index);
 123     }
 124   }
 125 
 126   return NULL;
 127 }
 128 
 129 void ShenandoahHeapRegionSet::print_on(outputStream* out) const {
 130   out->print_cr("Region Set : " SIZE_FORMAT "", count());
 131 
 132   debug_only(size_t regions = 0;)
 133   for (size_t index = 0; index < _heap->num_regions(); index ++) {
 134     if (is_in(index)) {
 135       _heap->get_region(index)->print_on(out);
 136       debug_only(regions ++;)
 137     }
 138   }
 139   assert(regions == count(), "Must match");
 140 }