/*

 * Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_VM_ADLC_ARENA_HPP

#define SHARE_VM_ADLC_ARENA_HPP

// All classes in the virtual machine must be subclassed

// by one of the following allocation classes:

//

//

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

// - CHeapObj

//

//

// For embedded objects.

// - ValueObj

//

// For classes used as name spaces.

// - AllStatic

//

class CHeapObj {

 public:

  void* operator new(size_t size);

  void  operator delete(void* p);

  void* new_array(size_t size);

};

// Base class for objects used as value objects.

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

class ValueObj {

 public:

  void* operator new(size_t size);

  void operator delete(void* p);

};

// Base class for classes that constitute name spaces.

class AllStatic {

 public:

  void* operator new(size_t size);

  void operator delete(void* p);

};

//------------------------------Chunk------------------------------------------

// Linked list of raw memory chunks

class Chunk: public CHeapObj {

 public:

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

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

  Chunk(size_t length);

  enum {

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

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

  };

  Chunk*       _next;           // Next Chunk in list

  size_t       _len;            // Size of this Chunk

  void chop();                  // Chop this chunk

  void next_chop();             // Chop next chunk

  // Boundaries of data area (possibly unused)

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

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

};

//------------------------------Arena------------------------------------------

// Fast allocation of memory

class Arena: public CHeapObj {

protected:

  friend class ResourceMark;

  friend class HandleMark;

  friend class NoHandleMark;

  Chunk *_first;                // First chunk

  Chunk *_chunk;                // current chunk

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

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

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

public:

  Arena();

  Arena(size_t init_size);

  Arena(Arena *old);

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

  char* hwm() const             { return _hwm; }

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

  void* Amalloc(size_t x) {

#ifdef _LP64

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

#else

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

#endif

    if (_hwm + x > _max) {

      return grow(x);

    } else {

      char *old = _hwm;

      _hwm += x;

      return old;

    }

  }

  // Further assume size is padded out to words

  // Warning:  in LP64, Amalloc_4 is really Amalloc_8

  void *Amalloc_4(size_t x) {

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

    if (_hwm + x > _max) {

      return grow(x);

    } else {

      char *old = _hwm;

      _hwm += x;

      return old;

    }

  }

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

  void Afree(void *ptr, size_t size) {

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

  }

  void *Acalloc( size_t items, size_t x );

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

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

  Arena *reset(void);

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

  bool contains( const void *ptr ) const;

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

  size_t used() const;

  // Total # of bytes used

  size_t size_in_bytes() const         {  return _size_in_bytes; }

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

};

#endif // SHARE_VM_ADLC_ARENA_HPP