/*

 * Copyright (c) 2015, 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/z/zAddressSpaceLimit.hpp"

#include "gc/z/zGlobals.hpp"

#include "gc/z/zVirtualMemory.inline.hpp"

#include "logging/log.hpp"

#include "services/memTracker.hpp"

#include "utilities/debug.hpp"

#include "utilities/align.hpp"

ZVirtualMemoryManager::ZVirtualMemoryManager(size_t max_capacity) :

    _manager(),

    _initialized(false) {

  // Check max supported heap size

  if (max_capacity > ZAddressOffsetMax) {

    log_error(gc)("Java heap too large (max supported heap size is " SIZE_FORMAT "G)",

                  ZAddressOffsetMax / G);

    return;

  }

  // Reserve address space

  if (!reserve(max_capacity)) {

    log_error(gc)("Failed to reserve enough address space for Java heap");

    return;

  }

  // Successfully initialized

  _initialized = true;

}

size_t ZVirtualMemoryManager::reserve_discontiguous(uintptr_t start, size_t size, size_t min_range) {

  if (size < min_range) {

    // Too small

    return 0;

  }

  assert(is_aligned(size, ZGranuleSize), "Misaligned");

  if (reserve_contiguous_platform(start, size)) {

    // Make the address range free

    _manager.free(start, size);

    return size;

  }

  const size_t half = size / 2;

  if (half < min_range) {

    // Too small

    return 0;

  }

  // Divide and conquer

  const size_t first_part = align_down(half, ZGranuleSize);

  const size_t second_part = size - first_part;

  return reserve_discontiguous(start, first_part, min_range) +

         reserve_discontiguous(start + first_part, second_part, min_range);

}

size_t ZVirtualMemoryManager::reserve_discontiguous(size_t size) {

  // Don't try to reserve address ranges smaller than 1% of the requested size.

  // This avoids an explosion of reservation attempts in case large parts of the

  // address space is already occupied.

  const size_t min_range = align_up(size / 100, ZGranuleSize);

  size_t start = 0;

  size_t reserved = 0;

  // Reserve size somewhere between [0, ZAddressOffsetMax)

  while (reserved < size && start < ZAddressOffsetMax) {

    const size_t remaining = MIN2(size - reserved, ZAddressOffsetMax - start);

    reserved += reserve_discontiguous(start, remaining, min_range);

    start += remaining;

  }

  return reserved;

}

bool ZVirtualMemoryManager::reserve_contiguous(size_t size) {

  // Allow at most 8192 attempts spread evenly across [0, ZAddressOffsetMax)

  const size_t end = ZAddressOffsetMax - size;

  const size_t increment = align_up(end / 8192, ZGranuleSize);

  for (size_t start = 0; start <= end; start += increment) {

    if (reserve_contiguous_platform(start, size)) {

      // Make the address range free

      _manager.free(start, size);

      // Success

      return true;

    }

  }

  // Failed

  return false;

}

bool ZVirtualMemoryManager::reserve(size_t max_capacity) {

  const size_t limit = MIN2(ZAddressOffsetMax, ZAddressSpaceLimit::heap_view());

  const size_t size = MIN2(max_capacity * ZVirtualToPhysicalRatio, limit);

  size_t reserved = size;

  bool contiguous = true;

  // Prefer a contiguous address space

  if (!reserve_contiguous(size)) {

    // Fall back to a discontiguous address space

    reserved = reserve_discontiguous(size);

    contiguous = false;

  }

  log_info(gc, init)("Address Space Type: %s/%s/%s",

                     (contiguous ? "Contiguous" : "Discontiguous"),

                     (limit == ZAddressOffsetMax ? "Unrestricted" : "Restricted"),

                     (reserved == size ? "Complete" : "Degraded"));

  log_info(gc, init)("Address Space Size: " SIZE_FORMAT "M x " SIZE_FORMAT " = " SIZE_FORMAT "M",

                     reserved / M, ZHeapViews, (reserved * ZHeapViews) / M);

  return reserved >= max_capacity;

}

void ZVirtualMemoryManager::nmt_reserve(uintptr_t start, size_t size) {

  MemTracker::record_virtual_memory_reserve((void*)start, size, CALLER_PC);

  MemTracker::record_virtual_memory_type((void*)start, mtJavaHeap);

}

bool ZVirtualMemoryManager::is_initialized() const {

  return _initialized;

}

ZVirtualMemory ZVirtualMemoryManager::alloc(size_t size, bool alloc_from_front) {

  uintptr_t start;

  if (alloc_from_front || size <= ZPageSizeSmall) {

    // Small page

    start = _manager.alloc_from_front(size);

  } else {

    // Medium/Large page

    start = _manager.alloc_from_back(size);

  }

  return ZVirtualMemory(start, size);

}

void ZVirtualMemoryManager::free(const ZVirtualMemory& vmem) {

  _manager.free(vmem.start(), vmem.size());

}