/*

 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

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

 *

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 * 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.

 *

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP

#include "memory/allocation.hpp"

#include "memory/memRegion.hpp"

#include "runtime/virtualspace.hpp"

#include "utilities/bitMap.hpp"

// Virtual space management helper for a virtual space with an OS page allocation

// granularity.

// (De-)Allocation requests are always OS page aligned by passing a page index

// and multiples of pages.

// The implementation gives an error when trying to commit or uncommit pages that

// have already been committed or uncommitted.

class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {

  friend class VMStructs;

 private:

  // Reserved area addresses.

  char* _low_boundary;

  char* _high_boundary;

  // The commit/uncommit granularity in bytes.

  size_t _page_size;

  // Bitmap used for verification of commit/uncommit operations.

  BitMap _committed;

  // Indicates that the entire space has been committed and pinned in memory,

  // os::commit_memory() or os::uncommit_memory() have no function.

  bool _special;

  // Indicates whether the committed space should be executable.

  bool _executable;

  // Returns the index of the page which contains the given address.

  uintptr_t  addr_to_page_index(char* addr) const;

  // Returns the address of the given page index.

  char*  page_start(uintptr_t index);

  // Returns the byte size of the given number of pages.

  size_t byte_size_for_pages(size_t num);

  // Returns true if the entire area is backed by committed memory.

  bool is_area_committed(uintptr_t start, size_t size_in_pages) const;

  // Returns true if the entire area is not backed by committed memory.

  bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;

 public:

  // Commit the given area of pages starting at start being size_in_pages large.

  MemRegion commit(uintptr_t start, size_t size_in_pages);

  // Uncommit the given area of pages starting at start being size_in_pages large.

  MemRegion uncommit(uintptr_t start, size_t size_in_pages);

  bool special() const { return _special; }

  // Initialization

  G1PageBasedVirtualSpace();

  bool initialize_with_granularity(ReservedSpace rs, size_t page_size);

  // Destruction

  ~G1PageBasedVirtualSpace();

  // Amount of reserved memory.

  size_t reserved_size() const;

  // Memory used in this virtual space.

  size_t committed_size() const;

  // Memory left to use/expand in this virtual space.

  size_t uncommitted_size() const;

  bool contains(const void* p) const;

  MemRegion reserved() {

    MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);

    return x;

  }

  void release();

  void check_for_contiguity() PRODUCT_RETURN;

  // Debugging

  void print_on(outputStream* out) PRODUCT_RETURN;

  void print();

};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP