1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   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_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP
  27 
  28 #include "gc_implementation/g1/g1PageBasedVirtualSpace.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "utilities/debug.hpp"
  31 
  32 class G1MappingChangedListener VALUE_OBJ_CLASS_SPEC {
  33  public:
  34   // Fired after commit of the memory, i.e. the memory this listener is registered
  35   // for can be accessed.
  36   // Zero_filled indicates that the memory can be considered as filled with zero bytes
  37   // when called.
  38   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled) = 0;
  39 };
  40 
  41 // Maps region based commit/uncommit requests to the underlying page sized virtual
  42 // space.
  43 class G1RegionToSpaceMapper : public CHeapObj<mtGC> {
  44  private:
  45   G1MappingChangedListener* _listener;
  46  protected:
  47   // Backing storage.
  48   G1PageBasedVirtualSpace _storage;
  49 
  50   size_t _region_granularity;
  51   // Mapping management
  52   BitMap _commit_map;
  53 
  54   G1RegionToSpaceMapper(ReservedSpace rs, size_t used_size, size_t page_size, size_t region_granularity, MemoryType type);
  55 
  56   void fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled);
  57  public:
  58   MemRegion reserved() { return _storage.reserved(); }
  59 
  60   void set_mapping_changed_listener(G1MappingChangedListener* listener) { _listener = listener; }
  61 
  62   virtual ~G1RegionToSpaceMapper() {
  63     _commit_map.resize(0, /* in_resource_area */ false);
  64   }
  65 
  66   bool is_committed(uintptr_t idx) const {
  67     return _commit_map.at(idx);
  68   }
  69 
  70   virtual void commit_regions(uint start_idx, size_t num_regions = 1) = 0;
  71   virtual void uncommit_regions(uint start_idx, size_t num_regions = 1) = 0;
  72 
  73   // Creates an appropriate G1RegionToSpaceMapper for the given parameters.
  74   // The actual space to be used within the given reservation is given by actual_size.
  75   // This is because some OSes need to round up the reservation size to guarantee
  76   // alignment of page_size.
  77   // The byte_translation_factor defines how many bytes in a region correspond to
  78   // a single byte in the data structure this mapper is for.
  79   // Eg. in the card table, this value corresponds to the size a single card
  80   // table entry corresponds to in the heap.
  81   static G1RegionToSpaceMapper* create_mapper(ReservedSpace rs,
  82                                               size_t actual_size,
  83                                               size_t page_size,
  84                                               size_t region_granularity,
  85                                               size_t byte_translation_factor,
  86                                               MemoryType type);
  87 };
  88 
  89 #endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP */