/*

 * Copyright (c) 2001, 2017, 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/g1/g1BiasedArray.hpp"

#include "gc/g1/g1RegionToSpaceMapper.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/virtualspace.hpp"

#include "services/memTracker.hpp"

#include "utilities/align.hpp"

#include "utilities/bitMap.inline.hpp"

G1RegionToSpaceMapper::G1RegionToSpaceMapper(ReservedSpace rs,

                                             size_t used_size,

                                             size_t page_size,

                                             size_t region_granularity,

                                             size_t commit_factor,

                                             MemoryType type) :

  _storage(rs, used_size, page_size),

  _region_granularity(region_granularity),

  _listener(NULL),

  _commit_map(rs.size() * commit_factor / region_granularity, mtGC) {

  guarantee(is_power_of_2(page_size), "must be");

  guarantee(is_power_of_2(region_granularity), "must be");

  MemTracker::record_virtual_memory_type((address)rs.base(), type);

}

// G1RegionToSpaceMapper implementation where the region granularity is larger than

// or the same as the commit granularity.

// Basically, the space corresponding to one region region spans several OS pages.

class G1RegionsLargerThanCommitSizeMapper : public G1RegionToSpaceMapper {

 private:

  size_t _pages_per_region;

 public:

  G1RegionsLargerThanCommitSizeMapper(ReservedSpace rs,

                                      size_t actual_size,

                                      size_t page_size,

                                      size_t alloc_granularity,

                                      size_t commit_factor,

                                      MemoryType type) :

    G1RegionToSpaceMapper(rs, actual_size, page_size, alloc_granularity, commit_factor, type),

    _pages_per_region(alloc_granularity / (page_size * commit_factor)) {

    guarantee(alloc_granularity >= page_size, "allocation granularity smaller than commit granularity");

  }

  virtual void commit_regions(uint start_idx, size_t num_regions, WorkGang* pretouch_gang) {

    size_t const start_page = (size_t)start_idx * _pages_per_region;

    bool zero_filled = _storage.commit(start_page, num_regions * _pages_per_region);

    if (AlwaysPreTouch) {

      _storage.pretouch(start_page, num_regions * _pages_per_region, pretouch_gang);

    }

    _commit_map.set_range(start_idx, start_idx + num_regions);

    fire_on_commit(start_idx, num_regions, zero_filled);

  }

  virtual void uncommit_regions(uint start_idx, size_t num_regions) {

    _storage.uncommit((size_t)start_idx * _pages_per_region, num_regions * _pages_per_region);

    _commit_map.clear_range(start_idx, start_idx + num_regions);

  }

};

// G1RegionToSpaceMapper implementation where the region granularity is smaller

// than the commit granularity.

// Basically, the contents of one OS page span several regions.

class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {

 private:

  class CommitRefcountArray : public G1BiasedMappedArray<uint> {

   protected:

     virtual uint default_value() const { return 0; }

  };

  size_t _regions_per_page;

  CommitRefcountArray _refcounts;

  uintptr_t region_idx_to_page_idx(uint region) const {

    return region / _regions_per_page;

  }

 public:

  G1RegionsSmallerThanCommitSizeMapper(ReservedSpace rs,

                                       size_t actual_size,

                                       size_t page_size,

                                       size_t alloc_granularity,

                                       size_t commit_factor,

                                       MemoryType type) :

    G1RegionToSpaceMapper(rs, actual_size, page_size, alloc_granularity, commit_factor, type),

    _regions_per_page((page_size * commit_factor) / alloc_granularity), _refcounts() {

    guarantee((page_size * commit_factor) >= alloc_granularity, "allocation granularity smaller than commit granularity");

    _refcounts.initialize((HeapWord*)rs.base(), (HeapWord*)(rs.base() + align_up(rs.size(), page_size)), page_size);

  }

  virtual void commit_regions(uint start_idx, size_t num_regions, WorkGang* pretouch_gang) {

    size_t const NoPage = ~(size_t)0;

    size_t first_committed = NoPage;

    size_t num_committed = 0;

    bool all_zero_filled = true;

    for (uint i = start_idx; i < start_idx + num_regions; i++) {

      assert(!_commit_map.at(i), "Trying to commit storage at region %u that is already committed", i);

      size_t idx = region_idx_to_page_idx(i);

      uint old_refcount = _refcounts.get_by_index(idx);

      bool zero_filled = false;

      if (old_refcount == 0) {

        if (first_committed == NoPage) {

          first_committed = idx;

          num_committed = 1;

        } else {

          num_committed++;

        }

        zero_filled = _storage.commit(idx, 1);

      }

      all_zero_filled &= zero_filled;

      _refcounts.set_by_index(idx, old_refcount + 1);

      _commit_map.set_bit(i);

    }

    if (AlwaysPreTouch && num_committed > 0) {

      _storage.pretouch(first_committed, num_committed, pretouch_gang);

    }

    fire_on_commit(start_idx, num_regions, all_zero_filled);

  }

  virtual void uncommit_regions(uint start_idx, size_t num_regions) {

    for (uint i = start_idx; i < start_idx + num_regions; i++) {

      assert(_commit_map.at(i), "Trying to uncommit storage at region %u that is not committed", i);

      size_t idx = region_idx_to_page_idx(i);

      uint old_refcount = _refcounts.get_by_index(idx);

      assert(old_refcount > 0, "must be");

      if (old_refcount == 1) {

        _storage.uncommit(idx, 1);

      }

      _refcounts.set_by_index(idx, old_refcount - 1);

      _commit_map.clear_bit(i);

    }

  }

};

void G1RegionToSpaceMapper::fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled) {

  if (_listener != NULL) {

    _listener->on_commit(start_idx, num_regions, zero_filled);

  }

}

G1RegionToSpaceMapper* G1RegionToSpaceMapper::create_mapper(ReservedSpace rs,

                                                            size_t actual_size,

                                                            size_t page_size,

                                                            size_t region_granularity,

                                                            size_t commit_factor,

                                                            MemoryType type) {

  if (region_granularity >= (page_size * commit_factor)) {

    return new G1RegionsLargerThanCommitSizeMapper(rs, actual_size, page_size, region_granularity, commit_factor, type);

  } else {

    return new G1RegionsSmallerThanCommitSizeMapper(rs, actual_size, page_size, region_granularity, commit_factor, type);

  }

}