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 /*

  * Copyright (c) 1997, 2012, 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_MEMORY_RESOURCEAREA_HPP

 #define SHARE_VM_MEMORY_RESOURCEAREA_HPP

 #include "memory/allocation.hpp"

 #include "runtime/thread.inline.hpp"

 // 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;

   friend class VMStructs;

   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, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM) {

 #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, mtThread));

     }

 #endif

     return (char*)Amalloc(size, alloc_failmode);

   }

   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;

   size_t _size_in_bytes;

   void initialize(Thread *thread) {

     _area = thread->resource_area();

     _chunk = _area->_chunk;

     _hwm = _area->_hwm;

     _max= _area->_max;

     _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) {

     _size_in_bytes = r->_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

       // reset arena size before delete chunks. Otherwise, the total

       // arena size could exceed total chunk size

       assert(_area->size_in_bytes() > size_in_bytes(), "Sanity check");

       _area->set_size_in_bytes(size_in_bytes());

       _chunk->next_chop();

     } else {

       assert(_area->size_in_bytes() == size_in_bytes(), "Sanity check");

     }

     _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);

   }

   ~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() { return _size_in_bytes; }

 };

 //------------------------------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<mtInternal> {

 protected:

   ResourceArea *_area;          // Resource area to stack allocate

   Chunk *_chunk;                // saved arena chunk

   char *_hwm, *_max;

   size_t _size_in_bytes;

   void initialize(Thread *thread) {

     _area = thread->resource_area();

     _chunk = _area->_chunk;

     _hwm = _area->_hwm;

     _max= _area->_max;

     _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) {

     _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

       // reset arena size before delete chunks. Otherwise, the total

       // arena size could exceed total chunk size

       assert(_area->size_in_bytes() > size_in_bytes(), "Sanity check");

       _area->set_size_in_bytes(size_in_bytes());

       _chunk->next_chop();

     } else {

       assert(_area->size_in_bytes() == size_in_bytes(), "Sanity check");

     }

     _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);

   }

   ~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() { return _size_in_bytes; };

 };

 #endif // SHARE_VM_MEMORY_RESOURCEAREA_HPP