1 
   2 /*
   3  * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHFREESET_HPP
  26 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHFREESET_HPP
  27 
  28 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
  29 #include "gc/shenandoah/shenandoahHeap.hpp"
  30 
  31 class ShenandoahFreeSet : public CHeapObj<mtGC> {
  32 private:
  33   ShenandoahHeap* const _heap;
  34   CHeapBitMap _mutator_free_bitmap;
  35   CHeapBitMap _collector_free_bitmap;
  36   size_t _max;
  37 
  38   // Left-most and right-most region indexes. There are no free regions outside
  39   // of [left-most; right-most] index intervals
  40   size_t _mutator_leftmost, _mutator_rightmost;
  41   size_t _collector_leftmost, _collector_rightmost;
  42 
  43   size_t _capacity;
  44   size_t _used;
  45 
  46   void assert_bounds() const NOT_DEBUG_RETURN;
  47   void assert_heaplock_owned_by_current_thread() const NOT_DEBUG_RETURN;
  48   void assert_heaplock_not_owned_by_current_thread() const NOT_DEBUG_RETURN;
  49 
  50   bool is_mutator_free(size_t idx) const;
  51   bool is_collector_free(size_t idx) const;
  52 
  53   HeapWord* try_allocate_in(ShenandoahHeapRegion* region, ShenandoahAllocRequest& req, bool& in_new_region);
  54   HeapWord* allocate_single(ShenandoahAllocRequest& req, bool& in_new_region);
  55   HeapWord* allocate_contiguous(ShenandoahAllocRequest& req);
  56 
  57   void flip_to_gc(ShenandoahHeapRegion* r);
  58 
  59   void recompute_bounds();
  60   void adjust_bounds();
  61   bool touches_bounds(size_t num) const;
  62 
  63   void increase_used(size_t amount);
  64   void clear_internal();
  65 
  66   size_t collector_count() const { return _collector_free_bitmap.count_one_bits(); }
  67   size_t mutator_count()   const { return _mutator_free_bitmap.count_one_bits();   }
  68 
  69   void try_recycle_trashed(ShenandoahHeapRegion *r);
  70 
  71   bool is_empty_or_trash(ShenandoahHeapRegion *r);
  72   size_t alloc_capacity(ShenandoahHeapRegion *r);
  73   bool has_no_alloc_capacity(ShenandoahHeapRegion *r);
  74 
  75 public:
  76   ShenandoahFreeSet(ShenandoahHeap* heap, size_t max_regions);
  77 
  78   void clear();
  79   void rebuild();
  80 
  81   void recycle_trash();
  82 
  83   void log_status();
  84 
  85   size_t capacity()  const { return _capacity; }
  86   size_t used()      const { return _used;     }
  87   size_t available() const {
  88     assert(_used <= _capacity, "must use less than capacity");
  89     return _capacity - _used;
  90   }
  91 
  92   HeapWord* allocate(ShenandoahAllocRequest& req, bool& in_new_region);
  93   size_t unsafe_peek_free() const;
  94 
  95   void print_on(outputStream* out) const;
  96 };
  97 
  98 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHFREESET_HPP