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.
  22  *
  23  */
  24 
  25 #ifndef SHARE_MEMORY_METASPACE_SPACEMANAGER_HPP
  26 #define SHARE_MEMORY_METASPACE_SPACEMANAGER_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "memory/metaspace.hpp"
  30 #include "memory/metaspace/blockFreelist.hpp"
  31 #include "memory/metaspace/chunkAllocSequence.hpp"
  32 #include "memory/metaspace/chunkManager.hpp"
  33 #include "memory/metaspace/metaspaceCommon.hpp"
  34 
  35 class outputStream;
  36 class Mutex;
  37 
  38 namespace metaspace {
  39 
  40 
  41 // The SpaceManager:
  42 // - keeps a list of chunks-in-use by the class loader, as well as a current chunk used
  43 //   to allocate from
  44 // - keeps a dictionary of free MetaBlocks. Those can be remnants of a retired chunk or
  45 //   allocations which were not needed anymore for some reason (e.g. releasing half-allocated
  46 //   structures when class loading fails)
  47 
  48 class SpaceManager : public CHeapObj<mtClass> {
  49 
  50   // Lock handed down from the associated ClassLoaderData.
  51   //  Protects allocations from this space.
  52   Mutex* const _lock;
  53 
  54   // The chunk manager to allocate chunks from.
  55   ChunkManager* const _chunk_manager;
  56 
  57   // The chunk allocation strategy to use.
  58   const ChunkAllocSequence* const _chunk_alloc_sequence;
  59 
  60   // List of chunks in use by this SpaceManager.  Allocations
  61   // are done from the current chunk.  The list is used for deallocating
  62   // chunks when the SpaceManager is freed.
  63   Metachunk* _first_chunk;
  64   Metachunk* _current_chunk;
  65 
  66   // Prematurely released metablocks.
  67   BlockFreelist* _block_freelist;
  68 
  69 
  70   // Statistics
  71 
  72   // Running counters.
  73   // Note: capacity = used + free + waste + overhead. We do not keep running counters for
  74   // free and waste. Their sum can be deduced from the three other values.
  75   size_t _overhead_words;
  76   size_t _capacity_words;
  77   size_t _used_words;
  78   uint32_t _num_chunks_by_type[NUM_CHUNK_LEVELS];
  79 
  80 
  81   Mutex* lock() const                           { return _lock; }
  82   ChunkManager* chunk_manager() const           { return _chunk_manager; }
  83   const ChunkAllocSequence* chunk_alloc_sequence() const    { return _chunk_alloc_sequence; }
  84 
  85   Metachunk* first_chunk()                      { return _first_chunk; }
  86   BlockFreelist* block_freelist(); // created on demand only
  87 
  88   // The current chunk is unable to service a request. The remainder of the chunk is
  89   // chopped into blocks and fed into the _block_freelists, in the hope of later reuse.
  90   void retire_current_chunk();
  91 
  92 public:
  93 
  94   SpaceManager(ChunkManager* chunk_manager, const ChunkAllocSequence* alloc_sequence, Mutex* lock);
  95 
  96   ~SpaceManager();
  97 
  98   // Allocate memory from Metaspace. Will attempt to allocate from the _block_freelists,
  99   // failing that, from the current chunk; failing that, attempt to get a new chunk from
 100   // the associated ChunkManager.
 101   MetaWord* allocate(size_t word_size);
 102 
 103   // Prematurely returns a metaspace allocation to the _block_freelists because it is not
 104   // needed anymore.
 105   void deallocate(MetaWord* p, size_t word_size);
 106 
 107   // Run verifications. slow=true: verify chunk-internal integrity too.
 108   DEBUG_ONLY(void locked_verify(bool slow) const;)
 109 
 110 };
 111 
 112 } // namespace metaspace
 113 
 114 #endif // SHARE_MEMORY_METASPACE_SPACEMANAGER_HPP