1 /*
   2  * Copyright (c) 2018, 2019, 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.
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  24 
  25 #ifndef SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
  26 #define SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
  27 
  28 #include "memory/virtualspace.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "utilities/debug.hpp"
  31 #include "utilities/globalDefinitions.hpp"
  32 
  33 class outputStream;
  34 
  35 namespace metaspace {
  36 
  37 class Metachunk;
  38 class ChunkManager;
  39 class OccupancyMap;
  40 
  41 // A VirtualSpaceList node.
  42 class VirtualSpaceNode : public CHeapObj<mtClass> {
  43   friend class VirtualSpaceList;
  44 
  45   // Link to next VirtualSpaceNode
  46   VirtualSpaceNode* _next;
  47 
  48   // Whether this node is contained in class or metaspace.
  49   const bool _is_class;
  50 
  51   // total in the VirtualSpace
  52   ReservedSpace _rs;
  53   VirtualSpace _virtual_space;
  54   MetaWord* _top;
  55   // count of chunks contained in this VirtualSpace
  56   uintx _container_count;
  57 
  58   OccupancyMap* _occupancy_map;
  59 
  60   // Convenience functions to access the _virtual_space
  61   char* low()  const { return virtual_space()->low(); }
  62   char* high() const { return virtual_space()->high(); }
  63 
  64   // The first Metachunk will be allocated at the bottom of the
  65   // VirtualSpace
  66   Metachunk* first_chunk() { return (Metachunk*) bottom(); }
  67 
  68   // Committed but unused space in the virtual space
  69   size_t free_words_in_vs() const;
  70 
  71   // True if this node belongs to class metaspace.
  72   bool is_class() const { return _is_class; }
  73 
  74   // Helper function for take_from_committed: allocate padding chunks
  75   // until top is at the given address.
  76   void allocate_padding_chunks_until_top_is_at(MetaWord* target_top);
  77 
  78  public:
  79 
  80   VirtualSpaceNode(bool is_class, size_t byte_size);
  81   VirtualSpaceNode(bool is_class, ReservedSpace rs) :
  82     _next(NULL), _is_class(is_class), _rs(rs), _top(NULL), _container_count(0), _occupancy_map(NULL) {}
  83   ~VirtualSpaceNode();
  84 
  85   // Convenience functions for logical bottom and end
  86   MetaWord* bottom() const { return (MetaWord*) _virtual_space.low(); }
  87   MetaWord* end() const { return (MetaWord*) _virtual_space.high(); }
  88 
  89   const OccupancyMap* occupancy_map() const { return _occupancy_map; }
  90   OccupancyMap* occupancy_map() { return _occupancy_map; }
  91 
  92   bool contains(const void* ptr) { return ptr >= low() && ptr < high(); }
  93 
  94   size_t reserved_words() const  { return _virtual_space.reserved_size() / BytesPerWord; }
  95   size_t committed_words() const { return _virtual_space.actual_committed_size() / BytesPerWord; }
  96 
  97   bool is_pre_committed() const { return _virtual_space.special(); }
  98 
  99   // address of next available space in _virtual_space;
 100   // Accessors
 101   VirtualSpaceNode* next() { return _next; }
 102   void set_next(VirtualSpaceNode* v) { _next = v; }
 103 
 104   void set_top(MetaWord* v) { _top = v; }
 105 
 106   // Accessors
 107   VirtualSpace* virtual_space() const { return (VirtualSpace*) &_virtual_space; }
 108 
 109   // Returns true if "word_size" is available in the VirtualSpace
 110   bool is_available(size_t word_size) { return word_size <= pointer_delta(end(), _top, sizeof(MetaWord)); }
 111 
 112   MetaWord* top() const { return _top; }
 113   void inc_top(size_t word_size) { _top += word_size; }
 114 
 115   uintx container_count() { return _container_count; }
 116   void inc_container_count();
 117   void dec_container_count();
 118 
 119   // used and capacity in this single entry in the list
 120   size_t used_words_in_vs() const;
 121   size_t capacity_words_in_vs() const;
 122 
 123   bool initialize();
 124 
 125   // get space from the virtual space
 126   Metachunk* take_from_committed(size_t chunk_word_size);
 127 
 128   // Allocate a chunk from the virtual space and return it.
 129   Metachunk* get_chunk_vs(size_t chunk_word_size);
 130 
 131   // Expands the committed space by at least min_words words.
 132   bool expand_by(size_t min_words, size_t preferred_words);
 133 
 134   // In preparation for deleting this node, remove all the chunks
 135   // in the node from any freelist.
 136   void purge(ChunkManager* chunk_manager);
 137 
 138   // If an allocation doesn't fit in the current node a new node is created.
 139   // Allocate chunks out of the remaining committed space in this node
 140   // to avoid wasting that memory.
 141   // This always adds up because all the chunk sizes are multiples of
 142   // the smallest chunk size.
 143   void retire(ChunkManager* chunk_manager);
 144 
 145   void print_on(outputStream* st) const                 { print_on(st, K); }
 146   void print_on(outputStream* st, size_t scale) const;
 147   void print_map(outputStream* st, bool is_class) const;
 148 
 149   // Debug support
 150   DEBUG_ONLY(void mangle();)
 151   // Verify counters and basic structure. Slow mode: verify all chunks in depth and occupancy map.
 152   DEBUG_ONLY(void verify(bool slow);)
 153   // Verify that all free chunks in this node are ideally merged
 154   // (there should not be multiple small chunks where a large chunk could exist.)
 155   DEBUG_ONLY(void verify_free_chunks_are_ideally_merged();)
 156 
 157 };
 158 
 159 } // namespace metaspace
 160 
 161 #endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP