Region.cpp

/*******************************************************************************
 * Copyright IBM Corp. and others 2000
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#include "env/MemorySegment.hpp"
#include "env/SegmentProvider.hpp"
#include "env/Region.hpp"
#include "infra/ReferenceWrapper.hpp"
#include "env/TRMemory.hpp"

namespace TR {

Region::Region(TR::SegmentProvider &segmentProvider, TR::RawAllocator rawAllocator) :
   _bytesAllocated(0),
   _segmentProvider(segmentProvider),
   _rawAllocator(rawAllocator),
   _initialSegment(_initialSegmentArea.data, INITIAL_SEGMENT_SIZE),
   _currentSegment(TR::ref(_initialSegment)),
   _lastDestroyer(NULL)
   {
   }

Region::Region(const Region &prototype) :
   _bytesAllocated(0),
   _segmentProvider(prototype._segmentProvider),
   _rawAllocator(prototype._rawAllocator),
   _initialSegment(_initialSegmentArea.data, INITIAL_SEGMENT_SIZE),
   _currentSegment(TR::ref(_initialSegment)),
   _lastDestroyer(NULL)
   {
   }

Region::~Region() throw()
   {
   /*
    * Destroy all object instances that depend on the region
    * to manage their lifetimes.
    */
   Destroyer *lastDestroyer = _lastDestroyer;
   while (lastDestroyer != NULL)
      {
      lastDestroyer->destroy();
      lastDestroyer = lastDestroyer->prev();
      }

   for (
      TR::reference_wrapper<TR::MemorySegment> latestSegment(_currentSegment);
      latestSegment.get() != _initialSegment;
      latestSegment = _currentSegment
      )
      {
      _currentSegment = TR::ref(latestSegment.get().unlink());
      _segmentProvider.release(latestSegment);
      }
   TR_ASSERT(_currentSegment.get() == _initialSegment, "self-referencial link was broken");
   }

void *
Region::allocate(size_t const size, void *hint)
   {
   size_t const roundedSize = round(size);
   if (_currentSegment.get().remaining() >= roundedSize)
      {
      _bytesAllocated += roundedSize;
      return _currentSegment.get().allocate(roundedSize);
      }
   TR::MemorySegment &newSegment = _segmentProvider.request(roundedSize);
   TR_ASSERT(newSegment.remaining() >= roundedSize, "Allocated segment is too small");
   newSegment.link(_currentSegment.get());
   _currentSegment = TR::ref(newSegment);
   _bytesAllocated += roundedSize;
   return _currentSegment.get().allocate(roundedSize);
   }

void
Region::deallocate(void * allocation, size_t) throw()
   {
   }

size_t
Region::round(size_t bytes)
   {
   return (bytes+15) & (~15);
   }
}