/*

 * 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.

 *

 *

 */

// The resource area holds temporary data structures in the VM.

// The actual allocation areas are thread local. Typical usage:

//

//   ...

//   {

//     ResourceMark rm;

//     int foo[] = NEW_RESOURCE_ARRAY(int, 64);

//     ...

//   }

//   ...

//------------------------------ResourceArea-----------------------------------

// A ResourceArea is an Arena that supports safe usage of ResourceMark.

class ResourceArea: public Arena {

  friend class ResourceMark;

  friend class DeoptResourceMark;

  debug_only(int _nesting;)             // current # of nested ResourceMarks

  debug_only(static int _warned;)       // to suppress multiple warnings

public:

  ResourceArea() {

    debug_only(_nesting = 0;)

  }

  ResourceArea(size_t init_size) : Arena(init_size) {

    debug_only(_nesting = 0;);

  }

  char* allocate_bytes(size_t size) {

#ifdef ASSERT

    if (_nesting < 1 && !_warned++)

      fatal("memory leak: allocating without ResourceMark");

    if (UseMallocOnly) {

      // use malloc, but save pointer in res. area for later freeing

      char** save = (char**)internal_malloc_4(sizeof(char*));

      return (*save = (char*)os::malloc(size));

    }

#endif

    return (char*)Amalloc(size);

  }

  debug_only(int nesting() const { return _nesting; });

};

//------------------------------ResourceMark-----------------------------------

// A resource mark releases all resources allocated after it was constructed

// when the destructor is called.  Typically used as a local variable.

class ResourceMark: public StackObj {

protected:

  ResourceArea *_area;          // Resource area to stack allocate

  Chunk *_chunk;                // saved arena chunk

  char *_hwm, *_max;

  NOT_PRODUCT(size_t _size_in_bytes;)

  void initialize(Thread *thread) {

    _area = thread->resource_area();

    _chunk = _area->_chunk;

    _hwm = _area->_hwm;

    _max= _area->_max;

    NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)

    debug_only(_area->_nesting++;)

    assert( _area->_nesting > 0, "must stack allocate RMs" );

  }

 public:

#ifndef ASSERT

  ResourceMark(Thread *thread) {

    assert(thread == Thread::current(), "not the current thread");

    initialize(thread);

  }

#else

  ResourceMark(Thread *thread);

#endif // ASSERT

  ResourceMark()               { initialize(Thread::current()); }

  ResourceMark( ResourceArea *r ) :

    _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {

    NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)

    debug_only(_area->_nesting++;)

    assert( _area->_nesting > 0, "must stack allocate RMs" );

  }

  void reset_to_mark() {

    if (UseMallocOnly) free_malloced_objects();

    if( _chunk->next() )        // Delete later chunks

      _chunk->next_chop();

    _area->_chunk = _chunk;     // Roll back arena to saved chunk

    _area->_hwm = _hwm;

    _area->_max = _max;

    // clear out this chunk (to detect allocation bugs)

    if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);

    _area->set_size_in_bytes(size_in_bytes());

  }

  ~ResourceMark() {

    assert( _area->_nesting > 0, "must stack allocate RMs" );

    debug_only(_area->_nesting--;)

    reset_to_mark();

  }

 private:

  void free_malloced_objects()                                         PRODUCT_RETURN;

  size_t size_in_bytes()       NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;

};

//------------------------------DeoptResourceMark-----------------------------------

// A deopt resource mark releases all resources allocated after it was constructed

// when the destructor is called.  Typically used as a local variable. It differs

// from a typical resource more in that it is C-Heap allocated so that deoptimization

// can use data structures that are arena based but are not amenable to vanilla

// ResourceMarks because deoptimization can not use a stack allocated mark. During

// deoptimization we go thru the following steps:

//

// 0: start in assembly stub and call either uncommon_trap/fetch_unroll_info

// 1: create the vframeArray (contains pointers to Resource allocated structures)

//   This allocates the DeoptResourceMark.

// 2: return to assembly stub and remove stub frame and deoptee frame and create

//    the new skeletal frames.

// 3: push new stub frame and call unpack_frames

// 4: retrieve information from the vframeArray to populate the skeletal frames

// 5: release the DeoptResourceMark

// 6: return to stub and eventually to interpreter

//

// With old style eager deoptimization the vframeArray was created by the vmThread there

// was no way for the vframeArray to contain resource allocated objects and so

// a complex set of data structures to simulate an array of vframes in CHeap memory

// was used. With new style lazy deoptimization the vframeArray is created in the

// the thread that will use it and we can use a much simpler scheme for the vframeArray

// leveraging existing data structures if we simply create a way to manage this one

// special need for a ResourceMark. If ResourceMark simply inherited from CHeapObj

// then existing ResourceMarks would work fine since no one use new to allocate them

// and they would be stack allocated. This leaves open the possibilty of accidental

// misuse so we simple duplicate the ResourceMark functionality here.

class DeoptResourceMark: public CHeapObj {

protected:

  ResourceArea *_area;          // Resource area to stack allocate

  Chunk *_chunk;                // saved arena chunk

  char *_hwm, *_max;

  NOT_PRODUCT(size_t _size_in_bytes;)

  void initialize(Thread *thread) {

    _area = thread->resource_area();

    _chunk = _area->_chunk;

    _hwm = _area->_hwm;

    _max= _area->_max;

    NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)

    debug_only(_area->_nesting++;)

    assert( _area->_nesting > 0, "must stack allocate RMs" );

  }

 public:

#ifndef ASSERT

  DeoptResourceMark(Thread *thread) {

    assert(thread == Thread::current(), "not the current thread");

    initialize(thread);

  }

#else

  DeoptResourceMark(Thread *thread);

#endif // ASSERT

  DeoptResourceMark()               { initialize(Thread::current()); }

  DeoptResourceMark( ResourceArea *r ) :

    _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {

    NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)

    debug_only(_area->_nesting++;)

    assert( _area->_nesting > 0, "must stack allocate RMs" );

  }

  void reset_to_mark() {

    if (UseMallocOnly) free_malloced_objects();

    if( _chunk->next() )        // Delete later chunks

      _chunk->next_chop();

    _area->_chunk = _chunk;     // Roll back arena to saved chunk

    _area->_hwm = _hwm;

    _area->_max = _max;

    // clear out this chunk (to detect allocation bugs)

    if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);

    _area->set_size_in_bytes(size_in_bytes());

  }

  ~DeoptResourceMark() {

    assert( _area->_nesting > 0, "must stack allocate RMs" );

    debug_only(_area->_nesting--;)

    reset_to_mark();

  }

 private:

  void free_malloced_objects()                                         PRODUCT_RETURN;

  size_t size_in_bytes()       NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;

};