/*

 * Copyright (c) 2018, 2019, 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.

 *

 */

#include "precompiled.hpp"

#include "gc/parallel/psFileBackedVirtualspace.hpp"

#include "memory/virtualspace.hpp"

#include "runtime/os.inline.hpp"

PSFileBackedVirtualSpace::PSFileBackedVirtualSpace(ReservedSpace rs, size_t alignment, const char* path) : PSVirtualSpace(rs, alignment),

                                                   _file_path(path), _fd(-1), _mapping_succeeded(false) {

  assert(!rs.special(), "ReservedSpace passed to PSFileBackedVirtualSpace cannot be special");

}

bool PSFileBackedVirtualSpace::initialize() {

  _fd = os::create_file_for_heap(_file_path);

  if (_fd == -1) {

    return false;

  }

  // We map the reserved space to a file at initialization.

  char* ret = os::replace_existing_mapping_with_file_mapping(reserved_low_addr(), reserved_size(), _fd);

  if (ret != reserved_low_addr()) {

    os::close(_fd);

    return false;

  }

  // _mapping_succeeded is false if we return before this point.

  // expand calls later check value of this flag and return error if it is false.

  _mapping_succeeded = true;

  _special = true;

  os::close(_fd);

  return true;

}

bool PSFileBackedVirtualSpace::expand_by(size_t bytes) {

  assert(special(), "Since entire space is committed at initialization, _special should always be true for PSFileBackedVirtualSpace");

  // if mapping did not succeed during intialization return false

  if (!_mapping_succeeded) {

    return false;

  }

  return PSVirtualSpace::expand_by(bytes);

}

bool PSFileBackedVirtualSpace::shrink_by(size_t bytes) {

  assert(special(), "Since entire space is committed at initialization, _special should always be true for PSFileBackedVirtualSpace");

  return PSVirtualSpace::shrink_by(bytes);

}

size_t PSFileBackedVirtualSpace::expand_into(PSVirtualSpace* space, size_t bytes) {

  // not supported. Since doing this will change page mapping which will lead to large TLB penalties.

  assert(false, "expand_into() should not be called for PSFileBackedVirtualSpace");

  return 0;

}

void PSFileBackedVirtualSpace::release() {

  os::close(_fd);

  _fd = -1;

  _file_path = NULL;

  PSVirtualSpace::release();

}