/*

 * Copyright (c) 2014, 2018, 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/g1PageBasedVirtualSpace.hpp"

#include "gc/shared/workgroup.hpp"

#include "oops/markWord.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/os.inline.hpp"

#include "services/memTracker.hpp"

#include "utilities/align.hpp"

#include "utilities/bitMap.inline.hpp"

G1PageBasedVirtualSpace::G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size) :

  _low_boundary(NULL), _high_boundary(NULL), _tail_size(0), _page_size(0),

  _committed(mtGC), _dirty(mtGC), _special(false), _executable(false) {

  initialize_with_page_size(rs, used_size, page_size);

}

void G1PageBasedVirtualSpace::initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size) {

  guarantee(rs.is_reserved(), "Given reserved space must have been reserved already.");

  vmassert(_low_boundary == NULL, "VirtualSpace already initialized");

  vmassert(page_size > 0, "Page size must be non-zero.");

  guarantee(is_aligned(rs.base(), page_size),

            "Reserved space base " PTR_FORMAT " is not aligned to requested page size " SIZE_FORMAT, p2i(rs.base()), page_size);

  guarantee(is_aligned(used_size, os::vm_page_size()),

            "Given used reserved space size needs to be OS page size aligned (%d bytes) but is " SIZE_FORMAT, os::vm_page_size(), used_size);

  guarantee(used_size <= rs.size(),

            "Used size of reserved space " SIZE_FORMAT " bytes is smaller than reservation at " SIZE_FORMAT " bytes", used_size, rs.size());

  guarantee(is_aligned(rs.size(), page_size),

            "Expected that the virtual space is size aligned, but " SIZE_FORMAT " is not aligned to page size " SIZE_FORMAT, rs.size(), page_size);

  _low_boundary  = rs.base();

  _high_boundary = _low_boundary + used_size;

  _special = rs.special();

  _executable = rs.executable();

  _page_size = page_size;

  vmassert(_committed.size() == 0, "virtual space initialized more than once");

  BitMap::idx_t size_in_pages = rs.size() / page_size;

  _committed.initialize(size_in_pages);

  if (_special) {

    _dirty.initialize(size_in_pages);

  }

  _tail_size = used_size % _page_size;

}

G1PageBasedVirtualSpace::~G1PageBasedVirtualSpace() {

  // This does not release memory it never reserved.

  // Caller must release via rs.release();

  _low_boundary           = NULL;

  _high_boundary          = NULL;

  _special                = false;

  _executable             = false;

  _page_size              = 0;

  _tail_size              = 0;

}

size_t G1PageBasedVirtualSpace::committed_size() const {

  size_t result = _committed.count_one_bits() * _page_size;

  // The last page might not be in full.

  if (is_last_page_partial() && _committed.at(_committed.size() - 1)) {

    result -= _page_size - _tail_size;

  }

  return result;

}

size_t G1PageBasedVirtualSpace::reserved_size() const {

  return pointer_delta(_high_boundary, _low_boundary, sizeof(char));

}

size_t G1PageBasedVirtualSpace::uncommitted_size()  const {

  return reserved_size() - committed_size();

}

void G1PageBasedVirtualSpace::commit_and_set_special() {

  commit_internal(addr_to_page_index(_low_boundary), addr_to_page_index(_high_boundary));

  _special = true;

  _dirty.initialize(reserved_size()/_page_size);

}

size_t G1PageBasedVirtualSpace::addr_to_page_index(char* addr) const {

  return (addr - _low_boundary) / _page_size;

}

bool G1PageBasedVirtualSpace::is_area_committed(size_t start_page, size_t size_in_pages) const {

  size_t end_page = start_page + size_in_pages;

  return _committed.get_next_zero_offset(start_page, end_page) >= end_page;

}

bool G1PageBasedVirtualSpace::is_area_uncommitted(size_t start_page, size_t size_in_pages) const {

  size_t end_page = start_page + size_in_pages;

  return _committed.get_next_one_offset(start_page, end_page) >= end_page;

}

char* G1PageBasedVirtualSpace::page_start(size_t index) const {

  return _low_boundary + index * _page_size;

}

bool G1PageBasedVirtualSpace::is_after_last_page(size_t index) const {

  guarantee(index <= _committed.size(),

            "Given boundary page " SIZE_FORMAT " is beyond managed page count " SIZE_FORMAT, index, _committed.size());

  return index == _committed.size();

}

void G1PageBasedVirtualSpace::commit_preferred_pages(size_t start, size_t num_pages) {

  vmassert(num_pages > 0, "No full pages to commit");

  vmassert(start + num_pages <= _committed.size(),

           "Tried to commit area from page " SIZE_FORMAT " to page " SIZE_FORMAT " "

           "that is outside of managed space of " SIZE_FORMAT " pages",

           start, start + num_pages, _committed.size());

  char* start_addr = page_start(start);

  size_t size = num_pages * _page_size;

  os::commit_memory_or_exit(start_addr, size, _page_size, _executable,

                            err_msg("Failed to commit area from " PTR_FORMAT " to " PTR_FORMAT " of length " SIZE_FORMAT ".",

                            p2i(start_addr), p2i(start_addr + size), size));

}

void G1PageBasedVirtualSpace::commit_tail() {

  vmassert(_tail_size > 0, "The size of the tail area must be > 0 when reaching here");

  char* const aligned_end_address = align_down(_high_boundary, _page_size);

  os::commit_memory_or_exit(aligned_end_address, _tail_size, os::vm_page_size(), _executable,

                            err_msg("Failed to commit tail area from " PTR_FORMAT " to " PTR_FORMAT " of length " SIZE_FORMAT ".",

                            p2i(aligned_end_address), p2i(_high_boundary), _tail_size));

}

void G1PageBasedVirtualSpace::commit_internal(size_t start_page, size_t end_page) {

  guarantee(start_page < end_page,

            "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);

  guarantee(end_page <= _committed.size(),

            "Given end page " SIZE_FORMAT " is beyond end of managed page amount of " SIZE_FORMAT, end_page, _committed.size());

  size_t pages = end_page - start_page;

  bool need_to_commit_tail = is_after_last_page(end_page) && is_last_page_partial();

  // If we have to commit some (partial) tail area, decrease the amount of pages to avoid

  // committing that in the full-page commit code.

  if (need_to_commit_tail) {

    pages--;

  }

  if (pages > 0) {

    commit_preferred_pages(start_page, pages);

  }

  if (need_to_commit_tail) {

    commit_tail();

  }

}

char* G1PageBasedVirtualSpace::bounded_end_addr(size_t end_page) const {

  return MIN2(_high_boundary, page_start(end_page));

}

void G1PageBasedVirtualSpace::pretouch_internal(size_t start_page, size_t end_page) {

  guarantee(start_page < end_page,

            "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);

  os::pretouch_memory(page_start(start_page), bounded_end_addr(end_page), _page_size);

}

bool G1PageBasedVirtualSpace::commit(size_t start_page, size_t size_in_pages) {

  // We need to make sure to commit all pages covered by the given area.

  guarantee(is_area_uncommitted(start_page, size_in_pages), "Specified area is not uncommitted");

  bool zero_filled = true;

  size_t end_page = start_page + size_in_pages;

  if (_special) {

    // Check for dirty pages and update zero_filled if any found.

    if (_dirty.get_next_one_offset(start_page, end_page) < end_page) {

      zero_filled = false;

      _dirty.clear_range(start_page, end_page);

    }

  } else {

    commit_internal(start_page, end_page);

  }

  _committed.set_range(start_page, end_page);

  return zero_filled;

}

void G1PageBasedVirtualSpace::uncommit_internal(size_t start_page, size_t end_page) {

  guarantee(start_page < end_page,

            "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);

  char* start_addr = page_start(start_page);

  os::uncommit_memory(start_addr, pointer_delta(bounded_end_addr(end_page), start_addr, sizeof(char)));

}

void G1PageBasedVirtualSpace::uncommit(size_t start_page, size_t size_in_pages) {

  guarantee(is_area_committed(start_page, size_in_pages), "checking");

  size_t end_page = start_page + size_in_pages;

  if (_special) {

    // Mark that memory is dirty. If committed again the memory might

    // need to be cleared explicitly.

    _dirty.set_range(start_page, end_page);

  } else {

    uncommit_internal(start_page, end_page);

  }

  _committed.clear_range(start_page, end_page);

}

class G1PretouchTask : public AbstractGangTask {

private:

  char* volatile _cur_addr;

  char* const _start_addr;

  char* const _end_addr;

  size_t _page_size;

public:

  G1PretouchTask(char* start_address, char* end_address, size_t page_size) :

    AbstractGangTask("G1 PreTouch"),

    _cur_addr(start_address),

    _start_addr(start_address),

    _end_addr(end_address),

    _page_size(0) {

#ifdef LINUX

    _page_size = UseTransparentHugePages ? (size_t)os::vm_page_size(): page_size;

#else

    _page_size = page_size;

#endif

  }

  virtual void work(uint worker_id) {

    size_t const actual_chunk_size = MAX2(chunk_size(), _page_size);

    while (true) {

      char* touch_addr = Atomic::add(actual_chunk_size, &_cur_addr) - actual_chunk_size;

      if (touch_addr < _start_addr || touch_addr >= _end_addr) {

        break;

      }

      char* end_addr = touch_addr + MIN2(actual_chunk_size, pointer_delta(_end_addr, touch_addr, sizeof(char)));

      os::pretouch_memory(touch_addr, end_addr, _page_size);

    }

  }

  static size_t chunk_size() { return PreTouchParallelChunkSize; }

};

void G1PageBasedVirtualSpace::pretouch(size_t start_page, size_t size_in_pages, WorkGang* pretouch_gang) {

  G1PretouchTask cl(page_start(start_page), bounded_end_addr(start_page + size_in_pages), _page_size);

  if (pretouch_gang != NULL) {

    size_t num_chunks = MAX2((size_t)1, size_in_pages * _page_size / MAX2(G1PretouchTask::chunk_size(), _page_size));

    uint num_workers = MIN2((uint)num_chunks, pretouch_gang->active_workers());

    log_debug(gc, heap)("Running %s with %u workers for " SIZE_FORMAT " work units pre-touching " SIZE_FORMAT "B.",

                        cl.name(), num_workers, num_chunks, size_in_pages * _page_size);

    pretouch_gang->run_task(&cl, num_workers);

  } else {

    log_debug(gc, heap)("Running %s pre-touching " SIZE_FORMAT "B.",

                        cl.name(), size_in_pages * _page_size);

    cl.work(0);

  }

}

bool G1PageBasedVirtualSpace::contains(const void* p) const {

  return _low_boundary <= (const char*) p && (const char*) p < _high_boundary;

}

#ifndef PRODUCT

void G1PageBasedVirtualSpace::print_on(outputStream* out) {

  out->print   ("Virtual space:");

  if (_special) out->print(" (pinned in memory)");

  out->cr();

  out->print_cr(" - committed: " SIZE_FORMAT, committed_size());

  out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());

  out->print_cr(" - preferred page size: " SIZE_FORMAT, _page_size);

  out->print_cr(" - [low_b, high_b]: [" PTR_FORMAT ", " PTR_FORMAT "]",  p2i(_low_boundary), p2i(_high_boundary));

}

void G1PageBasedVirtualSpace::print() {

  print_on(tty);

}

#endif