1 /*
   2  * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
   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 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGIONSET_HPP
  25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGIONSET_HPP
  26 
  27 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  28 
  29 
  30 class ShenandoahHeapRegionSet : public CHeapObj<mtGC> {
  31 private:
  32   ShenandoahHeapRegion** _regions;
  33   // current region to be returned from get_next()
  34   ShenandoahHeapRegion** _current;
  35   ShenandoahHeapRegion** _next;
  36 
  37   // last inserted region.
  38   ShenandoahHeapRegion** _next_free;
  39   ShenandoahHeapRegion** _concurrent_next_free;
  40 
  41   // Maximum size of the set.
  42   const size_t _max_regions;
  43 
  44   size_t _garbage_threshold;
  45   size_t _free_threshold;
  46 
  47   size_t _available;
  48   size_t _used;
  49 
  50   void choose_collection_set(ShenandoahHeapRegion** regions, size_t length);
  51   void choose_collection_set_min_garbage(ShenandoahHeapRegion** regions, size_t length, size_t min_garbage);
  52   void choose_free_set(ShenandoahHeapRegion** regions, size_t length);
  53 
  54 public:
  55   ShenandoahHeapRegionSet(size_t max_regions);
  56 
  57   ShenandoahHeapRegionSet(size_t max_regions, ShenandoahHeapRegion** regions, size_t num_regions);
  58 
  59   ~ShenandoahHeapRegionSet();
  60 
  61   void set_garbage_threshold(size_t minimum_garbage) { _garbage_threshold = minimum_garbage;}
  62   void set_free_threshold(size_t minimum_free) { _free_threshold = minimum_free;}
  63 
  64   /**
  65    * Appends a region to the set. This is implemented to be concurrency-safe.
  66    */
  67   void append(ShenandoahHeapRegion* region);
  68 
  69   void clear();
  70 
  71   size_t length();
  72   size_t used_regions() {
  73     return _current - _regions;
  74   }
  75   size_t available_regions();
  76   void print();
  77 
  78   size_t garbage();
  79   size_t used();
  80   size_t live_data();
  81   size_t reclaimed() {return _reclaimed;}
  82 
  83   /**
  84    * Returns a pointer to the current region.
  85    */
  86    ShenandoahHeapRegion* current();
  87 
  88   /**
  89    * Gets the next region for allocation (from free-list).
  90    * If multiple threads are competing, one will succeed to
  91    * increment to the next region, the others will fail and return
  92    * the region that the succeeding thread got.
  93    */
  94   ShenandoahHeapRegion* get_next();
  95 
  96   /**
  97    * Claims next region for processing. This is implemented to be concurrency-safe.
  98    */
  99   ShenandoahHeapRegion* claim_next();
 100 
 101   void choose_collection_and_free_sets(ShenandoahHeapRegionSet* col_set, ShenandoahHeapRegionSet* free_set);
 102   void choose_collection_and_free_sets_min_garbage(ShenandoahHeapRegionSet* col_set, ShenandoahHeapRegionSet* free_set, size_t min_garbage);
 103 
 104   // Check for unreachable humongous regions and reclaim them.
 105   void reclaim_humongous_regions();
 106 
 107   void set_concurrent_iteration_safe_limits();
 108 
 109   void decrease_available(size_t num_bytes);
 110 
 111   size_t available() const;
 112   size_t used() const;
 113 
 114 private:
 115   void reclaim_humongous_region_at(ShenandoahHeapRegion** r);
 116 
 117   ShenandoahHeapRegion** limit_region(ShenandoahHeapRegion** region);
 118   size_t _reclaimed;
 119 
 120 };
 121 
 122 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGIONSET_HPP