1 /*
   2  * Copyright (c) 2011, 2012, 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
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  23  */
  24 #ifndef SHARE_VM_MEMORY_METASPACE_HPP
  25 #define SHARE_VM_MEMORY_METASPACE_HPP
  26 
  27 #include "memory/allocation.hpp"
  28 #include "memory/memRegion.hpp"
  29 #include "runtime/virtualspace.hpp"
  30 #include "utilities/exceptions.hpp"
  31 
  32 // Metaspace
  33 //
  34 // Metaspaces are Arenas for the VM's metadata.
  35 // They are allocated one per class loader object, and one for the null
  36 // bootstrap class loader
  37 // Eventually for bootstrap loader we'll have a read-only section and read-write
  38 // to write for DumpSharedSpaces and read for UseSharedSpaces
  39 //
  40 //    block X ---+       +-------------------+
  41 //               |       |  Virtualspace     |
  42 //               |       |                   |
  43 //               |       |                   |
  44 //               |       |-------------------|
  45 //               |       || Chunk            |
  46 //               |       ||                  |
  47 //               |       ||----------        |
  48 //               +------>||| block 0 |       |
  49 //                       ||----------        |
  50 //                       ||| block 1 |       |
  51 //                       ||----------        |
  52 //                       ||                  |
  53 //                       |-------------------|
  54 //                       |                   |
  55 //                       |                   |
  56 //                       +-------------------+
  57 //
  58 
  59 class ClassLoaderData;
  60 class Metablock;
  61 class MetaWord;
  62 class Mutex;
  63 class outputStream;
  64 class SpaceManager;
  65 
  66 // Metaspaces each have a  SpaceManager and allocations
  67 // are done by the SpaceManager.  Allocations are done
  68 // out of the current Metachunk.  When the current Metachunk
  69 // is exhausted, the SpaceManager gets a new one from
  70 // the current VirtualSpace.  When the VirtualSpace is exhausted
  71 // the SpaceManager gets a new one.  The SpaceManager
  72 // also manages freelists of available Chunks.
  73 //
  74 // Currently the space manager maintains the list of
  75 // virtual spaces and the list of chunks in use.  Its
  76 // allocate() method returns a block for use as a
  77 // quantum of metadata.
  78 
  79 class VirtualSpaceList;
  80 
  81 class Metaspace : public CHeapObj<mtClass> {
  82   friend class VMStructs;
  83   friend class SpaceManager;
  84   friend class VM_CollectForMetadataAllocation;
  85   friend class MetaspaceGC;
  86   friend class MetaspaceAux;
  87 
  88  public:
  89   enum MetadataType {ClassType, NonClassType};
  90 
  91  private:
  92   void initialize(Mutex* lock, size_t initial_size = 0);
  93 
  94   static size_t _first_chunk_word_size;
  95 
  96   SpaceManager* _vsm;
  97   SpaceManager* vsm() const { return _vsm; }
  98 
  99   SpaceManager* _class_vsm;
 100   SpaceManager* class_vsm() const { return _class_vsm; }
 101 
 102   MetaWord* allocate(size_t word_size, MetadataType mdtype);
 103 
 104   // Virtual Space lists for both classes and other metadata
 105   static VirtualSpaceList* _space_list;
 106   static VirtualSpaceList* _class_space_list;
 107 
 108   static VirtualSpaceList* space_list()       { return _space_list; }
 109   static VirtualSpaceList* class_space_list() { return _class_space_list; }
 110 
 111  public:
 112 
 113   Metaspace(Mutex* lock, size_t initial_size);
 114   Metaspace(Mutex* lock);
 115   ~Metaspace();
 116 
 117   // Initialize globals for Metaspace
 118   static void global_initialize();
 119   static void initialize_class_space(ReservedSpace rs);
 120 
 121   static size_t first_chunk_word_size() { return _first_chunk_word_size; }
 122 
 123   char*  bottom() const;
 124   size_t used_words(MetadataType mdtype) const;
 125   size_t free_words(MetadataType mdtype) const;
 126   size_t capacity_words(MetadataType mdtype) const;
 127   size_t waste_words(MetadataType mdtype) const;
 128 
 129   static Metablock* allocate(ClassLoaderData* loader_data, size_t size,
 130                             bool read_only, MetadataType mdtype, TRAPS);
 131   void deallocate(MetaWord* ptr, size_t byte_size, bool is_class);
 132 
 133   MetaWord* expand_and_allocate(size_t size,
 134                                 MetadataType mdtype);
 135 
 136   static bool is_initialized() { return _class_space_list != NULL; }
 137 
 138   static bool contains(const void *ptr);
 139   void dump(outputStream* const out) const;
 140 
 141   void print_on(outputStream* st) const;
 142   // Debugging support
 143   void verify();
 144 };
 145 
 146 class MetaspaceAux : AllStatic {
 147 
 148   // Statistics for class space and data space in metaspace.
 149   static size_t used_in_bytes(Metaspace::MetadataType mdtype);
 150   static size_t free_in_bytes(Metaspace::MetadataType mdtype);
 151   static size_t capacity_in_bytes(Metaspace::MetadataType mdtype);
 152   static size_t reserved_in_bytes(Metaspace::MetadataType mdtype);
 153 
 154   static size_t free_chunks_total(Metaspace::MetadataType mdtype);
 155   static size_t free_chunks_total_in_bytes(Metaspace::MetadataType mdtype);
 156 
 157  public:
 158   // Total of space allocated to metadata in all Metaspaces
 159   static size_t used_in_bytes() {
 160     return used_in_bytes(Metaspace::ClassType) +
 161            used_in_bytes(Metaspace::NonClassType);
 162   }
 163 
 164   // Total of available space in all Metaspaces
 165   // Total of capacity allocated to all Metaspaces.  This includes
 166   // space in Metachunks not yet allocated and in the Metachunk
 167   // freelist.
 168   static size_t capacity_in_bytes() {
 169     return capacity_in_bytes(Metaspace::ClassType) +
 170            capacity_in_bytes(Metaspace::NonClassType);
 171   }
 172 
 173   // Total space reserved in all Metaspaces
 174   static size_t reserved_in_bytes() {
 175     return reserved_in_bytes(Metaspace::ClassType) +
 176            reserved_in_bytes(Metaspace::NonClassType);
 177   }
 178 
 179   static size_t min_chunk_size();
 180 
 181   // Print change in used metadata.
 182   static void print_metaspace_change(size_t prev_metadata_used);
 183   static void print_on(outputStream * out);
 184   static void print_on(outputStream * out, Metaspace::MetadataType mdtype);
 185 
 186   static void print_waste(outputStream* out);
 187   static void dump(outputStream* out);
 188   static void verify_free_chunks();
 189 };
 190 
 191 // Metaspace are deallocated when their class loader are GC'ed.
 192 // This class implements a policy for inducing GC's to recover
 193 // Metaspaces.
 194 
 195 class MetaspaceGC : AllStatic {
 196 
 197   // The current high-water-mark for inducing a GC.  When
 198   // the capacity of all space in the virtual lists reaches this value,
 199   // a GC is induced and the value is increased.  This should be changed
 200   // to the space actually used for allocations to avoid affects of
 201   // fragmentation losses to partially used chunks.  Size is in words.
 202   static size_t _capacity_until_GC;
 203 
 204   // After a GC is done any allocation that fails should try to expand
 205   // the capacity of the Metaspaces.  This flag is set during attempts
 206   // to allocate in the VMGCOperation that does the GC.
 207   static bool _expand_after_GC;
 208 
 209   // For a CMS collection, signal that a concurrent collection should
 210   // be started.
 211   static bool _should_concurrent_collect;
 212 
 213   static uint _shrink_factor;
 214 
 215   static void set_capacity_until_GC(size_t v) { _capacity_until_GC = v; }
 216 
 217   static size_t shrink_factor() { return _shrink_factor; }
 218   void set_shrink_factor(uint v) { _shrink_factor = v; }
 219 
 220  public:
 221 
 222   static size_t capacity_until_GC() { return _capacity_until_GC; }
 223   static size_t capacity_until_GC_in_bytes() { return _capacity_until_GC * BytesPerWord; }
 224   static void inc_capacity_until_GC(size_t v) { _capacity_until_GC += v; }
 225   static void dec_capacity_until_GC(size_t v) {
 226     _capacity_until_GC = _capacity_until_GC > v ? _capacity_until_GC - v : 0;
 227   }
 228   static bool expand_after_GC()           { return _expand_after_GC; }
 229   static void set_expand_after_GC(bool v) { _expand_after_GC = v; }
 230 
 231   static bool should_concurrent_collect() { return _should_concurrent_collect; }
 232   static void set_should_concurrent_collect(bool v) {
 233     _should_concurrent_collect = v;
 234   }
 235 
 236   // The amount to increase the high-water-mark (_capacity_until_GC)
 237   static size_t delta_capacity_until_GC(size_t word_size);
 238 
 239   // It is expected that this will be called when the current capacity
 240   // has been used and a GC should be considered.
 241   static bool should_expand(VirtualSpaceList* vsl, size_t word_size);
 242 
 243   // Calculate the new high-water mark at which to induce
 244   // a GC.
 245   static void compute_new_size();
 246 };
 247 
 248 #endif // SHARE_VM_MEMORY_METASPACE_HPP