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/shenandoah/shenandoahCollectionSet.hpp"

    27 #include "gc/shenandoah/shenandoahHeap.inline.hpp"

    28 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"

    29 #include "gc/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 bool ShenandoahCollectionSet::add_region_check_for_duplicates(ShenandoahHeapRegion* r) {

    63   if (!is_in(r)) {

    64     add_region(r);

    65     return true;

    66   } else {

    67     return false;

    68   }

    69 }

    70 

    71 void ShenandoahCollectionSet::remove_region(ShenandoahHeapRegion* r) {

    72   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");

    73   assert(Thread::current()->is_VM_thread(), "Must be VMThread");

    74   assert(is_in(r), "Not in collection set");

    75   _cset_map[r->region_number()] = 0;

    76   _region_count --;

    77 }

    78 

    79 void ShenandoahCollectionSet::update_region_status() {

    80   for (size_t index = 0; index < _heap->num_regions(); index ++) {

    81     ShenandoahHeapRegion* r = _heap->get_region(index);

    82     if (is_in(r)) {

    83       r->make_cset();

    84     } else {

    85       assert (!r->is_cset(), "should not be cset");

    86     }

    87   }

    88 }

    89 

    90 void ShenandoahCollectionSet::clear() {

    91   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");

    92   Copy::zero_to_bytes(_cset_map, _map_size);

    93 

    94 #ifdef ASSERT

    95   for (size_t index = 0; index < _heap->num_regions(); index ++) {

    96     assert (!_heap->get_region(index)->is_cset(), "should have been cleared before");

    97   }

    98 #endif

    99 

   100   _garbage = 0;

   101   _live_data = 0;

   102   _used = 0;

   103 

   104   _region_count = 0;

   105   _current_index = 0;

   106 }

   107 

   108 ShenandoahHeapRegion* ShenandoahCollectionSet::claim_next() {

   109   size_t num_regions = _heap->num_regions();

   110   if (_current_index >= (jint)num_regions) {

   111     return NULL;

   112   }

   113 

   114   jint saved_current = _current_index;

   115   size_t index = (size_t)saved_current;

   116 

   117   while(index < num_regions) {

   118     if (is_in(index)) {

   119       jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);

   120       assert(cur >= (jint)saved_current, "Must move forward");

   121       if (cur == saved_current) {

   122         assert(is_in(index), "Invariant");

   123         return _heap->get_region(index);

   124       } else {

   125         index = (size_t)cur;

   126         saved_current = cur;

   127       }

   128     } else {

   129       index ++;

   130     }

   131   }

   132   return NULL;

   133 }

   134 

   135 ShenandoahHeapRegion* ShenandoahCollectionSet::next() {

   136   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");

   137   assert(Thread::current()->is_VM_thread(), "Must be VMThread");

   138   size_t num_regions = _heap->num_regions();

   139   for (size_t index = (size_t)_current_index; index < num_regions; index ++) {

   140     if (is_in(index)) {

   141       _current_index = (jint)(index + 1);

   142       return _heap->get_region(index);

   143     }

   144   }

   145 

   146   return NULL;

   147 }

   148 

   149 void ShenandoahCollectionSet::print_on(outputStream* out) const {

   150   out->print_cr("Collection Set : " SIZE_FORMAT "", count());

   151 

   152   debug_only(size_t regions = 0;)

   153   for (size_t index = 0; index < _heap->num_regions(); index ++) {

   154     if (is_in(index)) {

   155       _heap->get_region(index)->print_on(out);

   156       debug_only(regions ++;)

   157     }

   158   }

   159   assert(regions == count(), "Must match");

   160 }