1 /*
   2  * Copyright (c) 2016, 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 
  26 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
  27 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
  28 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
  29 #include "gc_implementation/shenandoah/shenandoahUtils.hpp"
  30 #include "runtime/atomic.hpp"
  31 #include "utilities/copy.hpp"
  32 
  33 ShenandoahCollectionSet::ShenandoahCollectionSet(ShenandoahHeap* heap, HeapWord* heap_base) :
  34   _map_size(heap->num_regions()),
  35   _region_size_bytes_shift(ShenandoahHeapRegion::region_size_bytes_shift()),
  36   _cset_map(NEW_C_HEAP_ARRAY(jbyte, _map_size, mtGC)),
  37   _biased_cset_map(_cset_map - ((uintx)heap_base >> _region_size_bytes_shift)),
  38   _heap(heap),
  39   _garbage(0),
  40   _live_data(0),
  41   _used(0),
  42   _region_count(0),
  43   _current_index(0) {
  44   // Use 1-byte data type
  45   STATIC_ASSERT(sizeof(jbyte) == 1);
  46 
  47   // Initialize cset map
  48   Copy::zero_to_bytes(_cset_map, _map_size);
  49 }
  50 
  51 void ShenandoahCollectionSet::add_region(ShenandoahHeapRegion* r) {
  52   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  53   assert(Thread::current()->is_VM_thread(), "Must be VMThread");
  54   assert(!is_in(r), "Already in collection set");
  55   _cset_map[r->region_number()] = 1;
  56   _region_count ++;
  57   _garbage += r->garbage();
  58   _live_data += r->get_live_data_bytes();
  59   _used += r->used();
  60 }
  61 
  62 void ShenandoahCollectionSet::remove_region(ShenandoahHeapRegion* r) {
  63   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  64   assert(Thread::current()->is_VM_thread(), "Must be VMThread");
  65   assert(is_in(r), "Not in collection set");
  66   _cset_map[r->region_number()] = 0;
  67   _region_count --;
  68 }
  69 
  70 void ShenandoahCollectionSet::update_region_status() {
  71   for (size_t index = 0; index < _heap->num_regions(); index ++) {
  72     ShenandoahHeapRegion* r = _heap->get_region(index);
  73     if (is_in(r)) {
  74       r->make_cset();
  75     } else {
  76       assert (!r->is_cset(), "should not be cset");
  77     }
  78   }
  79 }
  80 
  81 void ShenandoahCollectionSet::clear() {
  82   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
  83   Copy::zero_to_bytes(_cset_map, _map_size);
  84 
  85 #ifdef ASSERT
  86   for (size_t index = 0; index < _heap->num_regions(); index ++) {
  87     assert (!_heap->get_region(index)->is_cset(), "should have been cleared before");
  88   }
  89 #endif
  90 
  91   _garbage = 0;
  92   _live_data = 0;
  93   _used = 0;
  94 
  95   _region_count = 0;
  96   _current_index = 0;
  97 }
  98 
  99 ShenandoahHeapRegion* ShenandoahCollectionSet::claim_next() {
 100   size_t num_regions = _heap->num_regions();
 101   if (_current_index >= (jint)num_regions) {
 102     return NULL;
 103   }
 104 
 105   jint saved_current = _current_index;
 106   size_t index = (size_t)saved_current;
 107 
 108   while(index < num_regions) {
 109     if (is_in(index)) {
 110       jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);
 111       assert(cur >= (jint)saved_current, "Must move forward");
 112       if (cur == saved_current) {
 113         assert(is_in(index), "Invariant");
 114         return _heap->get_region(index);
 115       } else {
 116         index = (size_t)cur;
 117         saved_current = cur;
 118       }
 119     } else {
 120       index ++;
 121     }
 122   }
 123   return NULL;
 124 }
 125 
 126 ShenandoahHeapRegion* ShenandoahCollectionSet::next() {
 127   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
 128   assert(Thread::current()->is_VM_thread(), "Must be VMThread");
 129   size_t num_regions = _heap->num_regions();
 130   for (size_t index = (size_t)_current_index; index < num_regions; index ++) {
 131     if (is_in(index)) {
 132       _current_index = (jint)(index + 1);
 133       return _heap->get_region(index);
 134     }
 135   }
 136 
 137   return NULL;
 138 }
 139 
 140 void ShenandoahCollectionSet::print_on(outputStream* out) const {
 141   out->print_cr("Collection Set : " SIZE_FORMAT "", count());
 142 
 143   debug_only(size_t regions = 0;)
 144   for (size_t index = 0; index < _heap->num_regions(); index ++) {
 145     if (is_in(index)) {
 146       _heap->get_region(index)->print_on(out);
 147       debug_only(regions ++;)
 148     }
 149   }
 150   assert(regions == count(), "Must match");
 151 }