1 /*

     2  * Copyright 1998-2002 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 // All classes in the virtual machine must be subclassed

    26 // by one of the following allocation classes:

    27 //

    28 //

    29 // For objects allocated in the C-heap (managed by: free & malloc).

    30 // - CHeapObj

    31 //

    32 //

    33 // For embedded objects.

    34 // - ValueObj

    35 //

    36 // For classes used as name spaces.

    37 // - AllStatic

    38 //

    39 

    40 class CHeapObj {

    41  public:

    42   void* operator new(size_t size);

    43   void  operator delete(void* p);

    44   void* new_array(size_t size);

    45 };

    46 

    47 

    48 // Base class for objects used as value objects.

    49 // Calling new or delete will result in fatal error.

    50 

    51 class ValueObj {

    52  public:

    53   void* operator new(size_t size);

    54   void operator delete(void* p);

    55 };

    56 

    57 // Base class for classes that constitute name spaces.

    58 

    59 class AllStatic {

    60  public:

    61   void* operator new(size_t size);

    62   void operator delete(void* p);

    63 };

    64 

    65 

    66 //------------------------------Chunk------------------------------------------

    67 // Linked list of raw memory chunks

    68 class Chunk: public CHeapObj {

    69  public:

    70   void* operator new(size_t size, size_t length);

    71   void  operator delete(void* p, size_t length);

    72   Chunk(size_t length);

    73 

    74   enum {

    75       init_size =  1*1024,      // Size of first chunk

    76       size      = 32*1024       // Default size of an Arena chunk (following the first)

    77   };

    78   Chunk*       _next;           // Next Chunk in list

    79   size_t       _len;            // Size of this Chunk

    80 

    81   void chop();                  // Chop this chunk

    82   void next_chop();             // Chop next chunk

    83 

    84   // Boundaries of data area (possibly unused)

    85   char* bottom() const { return ((char*) this) + sizeof(Chunk);  }

    86   char* top()    const { return bottom() + _len; }

    87 };

    88 

    89 

    90 //------------------------------Arena------------------------------------------

    91 // Fast allocation of memory

    92 class Arena: public CHeapObj {

    93 protected:

    94   friend class ResourceMark;

    95   friend class HandleMark;

    96   friend class NoHandleMark;

    97   Chunk *_first;                // First chunk

    98   Chunk *_chunk;                // current chunk

    99   char *_hwm, *_max;            // High water mark and max in current chunk

   100   void* grow(size_t x);         // Get a new Chunk of at least size x

   101   size_t _size_in_bytes;          // Size of arena (used for memory usage tracing)

   102 public:

   103   Arena();

   104   Arena(size_t init_size);

   105   Arena(Arena *old);

   106   ~Arena()                      { _first->chop(); }

   107   char* hwm() const             { return _hwm; }

   108 

   109   // Fast allocate in the arena.  Common case is: pointer test + increment.

   110   void* Amalloc(size_t x) {

   111 #ifdef _LP64

   112     x = (x + (8-1)) & ((unsigned)(-8));

   113 #else

   114     x = (x + (4-1)) & ((unsigned)(-4));

   115 #endif

   116     if (_hwm + x > _max) {

   117       return grow(x);

   118     } else {

   119       char *old = _hwm;

   120       _hwm += x;

   121       return old;

   122     }

   123   }

   124   // Further assume size is padded out to words

   125   // Warning:  in LP64, Amalloc_4 is really Amalloc_8

   126   void *Amalloc_4(size_t x) {

   127     assert( (x&(sizeof(char*)-1)) == 0, "misaligned size" );

   128     if (_hwm + x > _max) {

   129       return grow(x);

   130     } else {

   131       char *old = _hwm;

   132       _hwm += x;

   133       return old;

   134     }

   135   }

   136 

   137   // Fast delete in area.  Common case is: NOP (except for storage reclaimed)

   138   void Afree(void *ptr, size_t size) {

   139     if (((char*)ptr) + size == _hwm) _hwm = (char*)ptr;

   140   }

   141 

   142   void *Acalloc( size_t items, size_t x );

   143   void *Arealloc( void *old_ptr, size_t old_size, size_t new_size );

   144 

   145   // Reset this Arena to empty, and return this Arenas guts in a new Arena.

   146   Arena *reset(void);

   147 

   148   // Determine if pointer belongs to this Arena or not.

   149   bool contains( const void *ptr ) const;

   150 

   151   // Total of all chunks in use (not thread-safe)

   152   size_t used() const;

   153 

   154   // Total # of bytes used

   155   size_t size_in_bytes() const         {  return _size_in_bytes; }

   156   void   set_size_in_bytes(size_t size)  { _size_in_bytes = size;   }

   157 };