Quelle memRegion.hpp Sprache: C

/*
* Copyright (c) 2000, 2022, 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_MEMORY_MEMREGION_HPP
#define SHARE_MEMORY_MEMREGION_HPP

#include "memory/allocation.hpp"
#include "utilities/debug.hpp"
#include "utilities/globalDefinitions.hpp"

// A very simple data structure representing a contiguous region
// region of address space.

// Note that MemRegions are typically passed by value, not by reference.
// The intent is that they remain very small and contain no
// objects. The copy constructor and destructor must be trivial,
// to support optimization for pass-by-value.
// These should almost never be allocated in heap but we do
// create MemRegions (in CardTable and G1CMRootMemRegions) on the heap so operator
// new and operator new [] were added for these special cases.

class MemRegion {
  friend class VMStructs;
private:
  HeapWord* _start;
  size_t    _word_size;

public:
  MemRegion() : _start(NULL), _word_size(0) {};
  MemRegion(HeapWord* start, size_t word_size) :
    _start(start), _word_size(word_size) {};
  MemRegion(HeapWord* start, HeapWord* end) :
    _start(start), _word_size(pointer_delta(end, start)) {
    assert(end >= start, "incorrect constructor arguments");
  }
  MemRegion(MetaWord* start, MetaWord* end) :
    _start((HeapWord*)start), _word_size(pointer_delta(end, start)) {
    assert(end >= start, "incorrect constructor arguments");
  }

  MemRegion intersection(const MemRegion mr2) const;
  // regions must overlap or be adjacent
  MemRegion _union(const MemRegion mr2) const;
  // minus will fail a guarantee if mr2 is interior to this,
  // since there's no way to return 2 disjoint regions.
  MemRegion minus(const MemRegion mr2) const;

  HeapWord* start() const { return _start; }
  HeapWord* end() const   { return _start + _word_size; }
  HeapWord* last() const  { return _start + _word_size - 1; }

  void set_start(HeapWord* start) { _start = start; }
  void set_end(HeapWord* end)     { _word_size = pointer_delta(end, _start); }
  void set_word_size(size_t word_size) {
    _word_size = word_size;
  }

  bool contains(const MemRegion mr2) const {
    return _start <= mr2._start && end() >= mr2.end();
  }
  bool contains(const void* addr) const {
    return addr >= (void*)_start && addr < (void*)end();
  }
  bool equals(const MemRegion mr2) const {
    // first disjunct since we do not have a canonical empty set
    return ((is_empty() && mr2.is_empty()) ||
            (start() == mr2.start() && end() == mr2.end()));
  }

  size_t byte_size() const { return _word_size * sizeof(HeapWord); }
  size_t word_size() const { return _word_size; }

  bool is_empty() const { return word_size() == 0; }

  // Creates and initializes an array of MemRegions of the given length.
  static MemRegion* create_array(size_t length, MEMFLAGS flags);
  static void destroy_array(MemRegion* array, size_t length);
};

// For iteration over MemRegion's.

class MemRegionClosure : public StackObj {
public:
  virtual void do_MemRegion(MemRegion mr) = 0;
};

// A ResourceObj version of MemRegionClosure

class MemRegionClosureRO: public MemRegionClosure {
public:
  void* operator new(size_t size) throw() {
    return resource_allocate_bytes(size);
  }

  void  operator delete(void* p) {} // nothing to do
};

#endif // SHARE_MEMORY_MEMREGION_HPP

quality100%

¤ Dauer der Verarbeitung: 0.26 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.