1 /*
   2  * Copyright (c) 2013, 2018, 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/shenandoah/shenandoahHeapRegionSet.hpp"
  26 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  27 #include "gc/shenandoah/shenandoahHeap.hpp"
  28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  30 #include "gc/shenandoah/shenandoahUtils.hpp"
  31 #include "runtime/atomic.hpp"
  32 #include "utilities/copy.hpp"
  33 
  34 ShenandoahHeapRegionSetIterator::ShenandoahHeapRegionSetIterator(const ShenandoahHeapRegionSet* const set) :
  35         _set(set), _heap(ShenandoahHeap::heap()), _current_index(0) {}
  36 
  37 void ShenandoahHeapRegionSetIterator::reset(const ShenandoahHeapRegionSet* const set) {
  38   _set = set;
  39   _current_index = 0;
  40 }
  41 
  42 ShenandoahHeapRegionSet::ShenandoahHeapRegionSet() :
  43   _heap(ShenandoahHeap::heap()),
  44   _map_size(_heap->num_regions()),
  45   _region_size_bytes_shift(ShenandoahHeapRegion::region_size_bytes_shift()),
  46   _set_map(NEW_C_HEAP_ARRAY(jbyte, _map_size, mtGC)),
  47   _biased_set_map(_set_map - ((uintx)_heap->base() >> _region_size_bytes_shift)),
  48   _region_count(0)
  49 {
  50   // Use 1-byte data type
  51   STATIC_ASSERT(sizeof(jbyte) == 1);
  52 
  53   // Initialize cset map
  54   Copy::zero_to_bytes(_set_map, _map_size);
  55 }
  56 
  57 ShenandoahHeapRegionSet::~ShenandoahHeapRegionSet() {
  58   FREE_C_HEAP_ARRAY(jbyte, _set_map);
  59 }
  60 
  61 void ShenandoahHeapRegionSet::add_region(ShenandoahHeapRegion* r) {
  62   assert(!is_in(r), "Already in collection set");
  63   _set_map[r->region_number()] = 1;
  64   _region_count++;
  65 }
  66 
  67 bool ShenandoahHeapRegionSet::add_region_check_for_duplicates(ShenandoahHeapRegion* r) {
  68   if (!is_in(r)) {
  69     add_region(r);
  70     return true;
  71   } else {
  72     return false;
  73   }
  74 }
  75 
  76 void ShenandoahHeapRegionSet::remove_region(ShenandoahHeapRegion* r) {
  77   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  78   assert(Thread::current()->is_VM_thread(), "Must be VMThread");
  79   assert(is_in(r), "Not in region set");
  80   _set_map[r->region_number()] = 0;
  81   _region_count --;
  82 }
  83 
  84 void ShenandoahHeapRegionSet::clear() {
  85   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  86   Copy::zero_to_bytes(_set_map, _map_size);
  87 
  88   _region_count = 0;
  89 }
  90 
  91 ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::claim_next() {
  92   size_t num_regions = _heap->num_regions();
  93   if (_current_index >= (jint)num_regions) {
  94     return NULL;
  95   }
  96 
  97   jint saved_current = _current_index;
  98   size_t index = (size_t)saved_current;
  99 
 100   while(index < num_regions) {
 101     if (_set->is_in(index)) {
 102       jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);
 103       assert(cur >= (jint)saved_current, "Must move forward");
 104       if (cur == saved_current) {
 105         assert(_set->is_in(index), "Invariant");
 106         return _heap->get_region(index);
 107       } else {
 108         index = (size_t)cur;
 109         saved_current = cur;
 110       }
 111     } else {
 112       index ++;
 113     }
 114   }
 115   return NULL;
 116 }
 117 
 118 ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::next() {
 119   size_t num_regions = _heap->num_regions();
 120   for (size_t index = (size_t)_current_index; index < num_regions; index ++) {
 121     if (_set->is_in(index)) {
 122       _current_index = (jint)(index + 1);
 123       return _heap->get_region(index);
 124     }
 125   }
 126 
 127   return NULL;
 128 }
 129 
 130 void ShenandoahHeapRegionSet::print_on(outputStream* out) const {
 131   out->print_cr("Region Set : " SIZE_FORMAT "", count());
 132 
 133   debug_only(size_t regions = 0;)
 134   for (size_t index = 0; index < _heap->num_regions(); index ++) {
 135     if (is_in(index)) {
 136       _heap->get_region(index)->print_on(out);
 137       debug_only(regions ++;)
 138     }
 139   }
 140   assert(regions == count(), "Must match");
 141 }