/*

 * Copyright (c) 2001, 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/shared/adaptiveSizePolicy.hpp"

#include "gc/shared/cardTableRS.hpp"

#include "gc/shared/collectorPolicy.hpp"

#include "gc/shared/gcLocker.hpp"

#include "gc/shared/gcPolicyCounters.hpp"

#include "gc/shared/generationSpec.hpp"

#include "gc/shared/space.hpp"

#include "gc/shared/vmGCOperations.hpp"

#include "logging/log.hpp"

#include "memory/universe.hpp"

#include "runtime/arguments.hpp"

#include "runtime/globals_extension.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/java.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/vmThread.hpp"

#include "utilities/align.hpp"

#include "utilities/macros.hpp"

// CollectorPolicy methods

CollectorPolicy::CollectorPolicy() :

    _initial_heap_byte_size(InitialHeapSize),

    _max_heap_byte_size(MaxHeapSize),

{}

#ifdef ASSERT

void CollectorPolicy::assert_flags() {

  assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");

  assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");

  assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");

}

void CollectorPolicy::assert_size_info() {

  assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");

  assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");

  assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");

  assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");

  assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");

  assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");

  assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");

  assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");

}

#endif // ASSERT

void CollectorPolicy::initialize_flags() {

  assert(_space_alignment != 0, "Space alignment not set up properly");

  assert(_heap_alignment != 0, "Heap alignment not set up properly");

  assert(_heap_alignment >= _space_alignment,

         "heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,

         _heap_alignment, _space_alignment);

  assert(_heap_alignment % _space_alignment == 0,

         "heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,

         _heap_alignment, _space_alignment);

  if (FLAG_IS_CMDLINE(MaxHeapSize)) {

    if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {

      vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");

    }

    if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {

      vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");

    }

  }

  // Check heap parameter properties

  if (MaxHeapSize < 2 * M) {

    vm_exit_during_initialization("Too small maximum heap");

  }

  if (InitialHeapSize < M) {

    vm_exit_during_initialization("Too small initial heap");

  }

  if (_min_heap_byte_size < M) {

    vm_exit_during_initialization("Too small minimum heap");

  }

  // User inputs from -Xmx and -Xms must be aligned

  _min_heap_byte_size = align_up(_min_heap_byte_size, _heap_alignment);

  size_t aligned_initial_heap_size = align_up(InitialHeapSize, _heap_alignment);

  size_t aligned_max_heap_size = align_up(MaxHeapSize, _heap_alignment);

  // Write back to flags if the values changed

  if (aligned_initial_heap_size != InitialHeapSize) {

    FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size);

  }

  if (aligned_max_heap_size != MaxHeapSize) {

    FLAG_SET_ERGO(size_t, MaxHeapSize, aligned_max_heap_size);

  }

  if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&

      InitialHeapSize < _min_heap_byte_size) {

    vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");

  }

  if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {

    FLAG_SET_ERGO(size_t, MaxHeapSize, InitialHeapSize);

  } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {

    FLAG_SET_ERGO(size_t, InitialHeapSize, MaxHeapSize);

    if (InitialHeapSize < _min_heap_byte_size) {

      _min_heap_byte_size = InitialHeapSize;

    }

  }

  _initial_heap_byte_size = InitialHeapSize;

  _max_heap_byte_size = MaxHeapSize;

  FLAG_SET_ERGO(size_t, MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, _space_alignment));

  DEBUG_ONLY(CollectorPolicy::assert_flags();)

}

void CollectorPolicy::initialize_size_info() {

  log_debug(gc, heap)("Minimum heap " SIZE_FORMAT "  Initial heap " SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,

                      _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);

  DEBUG_ONLY(CollectorPolicy::assert_size_info();)

}

size_t CollectorPolicy::compute_heap_alignment() {

  // The card marking array and the offset arrays for old generations are

  // committed in os pages as well. Make sure they are entirely full (to

  // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1

  // byte entry and the os page size is 4096, the maximum heap size should

  // be 512*4096 = 2MB aligned.

  size_t alignment = CardTableRS::ct_max_alignment_constraint();

  if (UseLargePages) {

      // In presence of large pages we have to make sure that our

      // alignment is large page aware.

      alignment = lcm(os::large_page_size(), alignment);

  }

  return alignment;

}

// GenCollectorPolicy methods

GenCollectorPolicy::GenCollectorPolicy() :

    _min_young_size(0),

    _initial_young_size(0),

    _max_young_size(0),

    _min_old_size(0),

    _initial_old_size(0),

    _max_old_size(0),

    _gen_alignment(0)

{}

size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {

  return align_down_bounded(base_size / (NewRatio + 1), _gen_alignment);

}

size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,

                                                 size_t maximum_size) {

  size_t max_minus = maximum_size - _gen_alignment;

  return desired_size < max_minus ? desired_size : max_minus;

}

size_t GenCollectorPolicy::young_gen_size_lower_bound() {

  // The young generation must be aligned and have room for eden + two survivors

  return align_up(3 * _space_alignment, _gen_alignment);

}

size_t GenCollectorPolicy::old_gen_size_lower_bound() {

  return align_up(_space_alignment, _gen_alignment);

}

#ifdef ASSERT

void GenCollectorPolicy::assert_flags() {

  CollectorPolicy::assert_flags();

  assert(NewSize >= _min_young_size, "Ergonomics decided on a too small young gen size");

  assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");

  assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");

  assert(NewSize % _gen_alignment == 0, "NewSize alignment");

  assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");

  assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");

  assert(OldSize % _gen_alignment == 0, "OldSize alignment");

}

void GenCollectorPolicy::assert_size_info() {

  CollectorPolicy::assert_size_info();

  // GenCollectorPolicy::initialize_size_info may update the MaxNewSize

  assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");

  assert(NewSize == _initial_young_size, "Discrepancy between NewSize flag and local storage");

  assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage");

  assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage");

  assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");

  assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");

  assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment");

  assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment");

  assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment");

  assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size),

      "Ergonomics made minimum young generation larger than minimum heap");

  assert(_initial_young_size <=  bound_minus_alignment(_initial_young_size, _initial_heap_byte_size),

      "Ergonomics made initial young generation larger than initial heap");

  assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size),

      "Ergonomics made maximum young generation lager than maximum heap");

  assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");

  assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");

  assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment");

  assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment");

  assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes");

  assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size");

  assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size");

  assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size");

}

#endif // ASSERT

void GenCollectorPolicy::initialize_flags() {

  CollectorPolicy::initialize_flags();

  assert(_gen_alignment != 0, "Generation alignment not set up properly");

  assert(_heap_alignment >= _gen_alignment,

         "heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,

         _heap_alignment, _gen_alignment);

  assert(_gen_alignment % _space_alignment == 0,

         "gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,

         _gen_alignment, _space_alignment);

  assert(_heap_alignment % _gen_alignment == 0,

         "heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,

         _heap_alignment, _gen_alignment);

  // All generational heaps have a young gen; handle those flags here

  // Make sure the heap is large enough for two generations

  size_t smallest_new_size = young_gen_size_lower_bound();

  size_t smallest_heap_size = align_up(smallest_new_size + old_gen_size_lower_bound(),

                                           _heap_alignment);

  if (MaxHeapSize < smallest_heap_size) {

    FLAG_SET_ERGO(size_t, MaxHeapSize, smallest_heap_size);

    _max_heap_byte_size = MaxHeapSize;

  }

  // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size

  if (_min_heap_byte_size < smallest_heap_size) {

    _min_heap_byte_size = smallest_heap_size;

    if (InitialHeapSize < _min_heap_byte_size) {

      FLAG_SET_ERGO(size_t, InitialHeapSize, smallest_heap_size);

      _initial_heap_byte_size = smallest_heap_size;

    }

  }

  // Make sure NewSize allows an old generation to fit even if set on the command line

  if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) {

    log_warning(gc, ergo)("NewSize was set larger than initial heap size, will use initial heap size.");

    FLAG_SET_ERGO(size_t, NewSize, bound_minus_alignment(NewSize, _initial_heap_byte_size));

  }

  // Now take the actual NewSize into account. We will silently increase NewSize

  // if the user specified a smaller or unaligned value.

  size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize);

  bounded_new_size = MAX2(smallest_new_size, align_down(bounded_new_size, _gen_alignment));

  if (bounded_new_size != NewSize) {

    FLAG_SET_ERGO(size_t, NewSize, bounded_new_size);

  }

  _min_young_size = smallest_new_size;

  _initial_young_size = NewSize;

  if (!FLAG_IS_DEFAULT(MaxNewSize)) {

    if (MaxNewSize >= MaxHeapSize) {

      // Make sure there is room for an old generation

      size_t smaller_max_new_size = MaxHeapSize - _gen_alignment;

      if (FLAG_IS_CMDLINE(MaxNewSize)) {

        log_warning(gc, ergo)("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "

                              "heap (" SIZE_FORMAT "k).  A new max generation size of " SIZE_FORMAT "k will be used.",

                              MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);

      }

      FLAG_SET_ERGO(size_t, MaxNewSize, smaller_max_new_size);

      if (NewSize > MaxNewSize) {

        FLAG_SET_ERGO(size_t, NewSize, MaxNewSize);

        _initial_young_size = NewSize;

      }

    } else if (MaxNewSize < _initial_young_size) {

      FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size);

    } else if (!is_aligned(MaxNewSize, _gen_alignment)) {

      FLAG_SET_ERGO(size_t, MaxNewSize, align_down(MaxNewSize, _gen_alignment));

    }

    _max_young_size = MaxNewSize;

  }

  if (NewSize > MaxNewSize) {

    // At this point this should only happen if the user specifies a large NewSize and/or

    // a small (but not too small) MaxNewSize.

    if (FLAG_IS_CMDLINE(MaxNewSize)) {

      log_warning(gc, ergo)("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "

                            "A new max generation size of " SIZE_FORMAT "k will be used.",

                            NewSize/K, MaxNewSize/K, NewSize/K);

    }

    FLAG_SET_ERGO(size_t, MaxNewSize, NewSize);

    _max_young_size = MaxNewSize;

  }

  if (SurvivorRatio < 1 || NewRatio < 1) {

    vm_exit_during_initialization("Invalid young gen ratio specified");

  }

  if (OldSize < old_gen_size_lower_bound()) {

    FLAG_SET_ERGO(size_t, OldSize, old_gen_size_lower_bound());

  }

  if (!is_aligned(OldSize, _gen_alignment)) {

    FLAG_SET_ERGO(size_t, OldSize, align_down(OldSize, _gen_alignment));

  }

  if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {

    // NewRatio will be used later to set the young generation size so we use

    // it to calculate how big the heap should be based on the requested OldSize

    // and NewRatio.

    assert(NewRatio > 0, "NewRatio should have been set up earlier");

    size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);

    calculated_heapsize = align_up(calculated_heapsize, _heap_alignment);

    FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize);

    _max_heap_byte_size = MaxHeapSize;

    FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize);

    _initial_heap_byte_size = InitialHeapSize;

  }

  // Adjust NewSize and OldSize or MaxHeapSize to match each other

  if (NewSize + OldSize > MaxHeapSize) {

    if (FLAG_IS_CMDLINE(MaxHeapSize)) {

      // Somebody has set a maximum heap size with the intention that we should not

      // exceed it. Adjust New/OldSize as necessary.

      size_t calculated_size = NewSize + OldSize;

      double shrink_factor = (double) MaxHeapSize / calculated_size;

      size_t smaller_new_size = align_down((size_t)(NewSize * shrink_factor), _gen_alignment);

      FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));

      _initial_young_size = NewSize;

      // OldSize is already aligned because above we aligned MaxHeapSize to

      // _heap_alignment, and we just made sure that NewSize is aligned to

      // _gen_alignment. In initialize_flags() we verified that _heap_alignment

      // is a multiple of _gen_alignment.

      FLAG_SET_ERGO(size_t, OldSize, MaxHeapSize - NewSize);

    } else {

      FLAG_SET_ERGO(size_t, MaxHeapSize, align_up(NewSize + OldSize, _heap_alignment));

      _max_heap_byte_size = MaxHeapSize;

    }

  }

  // Update NewSize, if possible, to avoid sizing the young gen too small when only

  // OldSize is set on the command line.

  if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) {

    if (OldSize < _initial_heap_byte_size) {

      size_t new_size = _initial_heap_byte_size - OldSize;

      // Need to compare against the flag value for max since _max_young_size

      // might not have been set yet.

      if (new_size >= _min_young_size && new_size <= MaxNewSize) {

        FLAG_SET_ERGO(size_t, NewSize, new_size);

        _initial_young_size = NewSize;

      }

    }

  }

  always_do_update_barrier = UseConcMarkSweepGC;

  DEBUG_ONLY(GenCollectorPolicy::assert_flags();)

}

// Values set on the command line win over any ergonomically

// set command line parameters.

// Ergonomic choice of parameters are done before this

// method is called.  Values for command line parameters such as NewSize

// and MaxNewSize feed those ergonomic choices into this method.

// This method makes the final generation sizings consistent with

// themselves and with overall heap sizings.

// In the absence of explicitly set command line flags, policies

// such as the use of NewRatio are used to size the generation.

// Minimum sizes of the generations may be different than

// the initial sizes.  An inconsistency is permitted here

// in the total size that can be specified explicitly by

// command line specification of OldSize and NewSize and

// also a command line specification of -Xms.  Issue a warning

// but allow the values to pass.

void GenCollectorPolicy::initialize_size_info() {

  CollectorPolicy::initialize_size_info();

  _initial_young_size = NewSize;

  _max_young_size = MaxNewSize;

  _initial_old_size = OldSize;

  // Determine maximum size of the young generation.

  if (FLAG_IS_DEFAULT(MaxNewSize)) {

    _max_young_size = scale_by_NewRatio_aligned(_max_heap_byte_size);

    // Bound the maximum size by NewSize below (since it historically

    // would have been NewSize and because the NewRatio calculation could

    // yield a size that is too small) and bound it by MaxNewSize above.

    // Ergonomics plays here by previously calculating the desired

    // NewSize and MaxNewSize.

    _max_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize);

  }

  // Given the maximum young size, determine the initial and

  // minimum young sizes.

  if (_max_heap_byte_size == _initial_heap_byte_size) {

    // The maximum and initial heap sizes are the same so the generation's

    // initial size must be the same as it maximum size. Use NewSize as the

    // size if set on command line.

    _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size;

    _initial_young_size = _max_young_size;

    // Also update the minimum size if min == initial == max.

    if (_max_heap_byte_size == _min_heap_byte_size) {

      _min_young_size = _max_young_size;

    }

  } else {

    if (FLAG_IS_CMDLINE(NewSize)) {

      // If NewSize is set on the command line, we should use it as

      // the initial size, but make sure it is within the heap bounds.

      _initial_young_size =

        MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size));

      _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size);

    } else {

      // For the case where NewSize is not set on the command line, use

      // NewRatio to size the initial generation size. Use the current

      // NewSize as the floor, because if NewRatio is overly large, the resulting

      // size can be too small.

      _initial_young_size =

        MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize));

    }

  }

  log_trace(gc, heap)("1: Minimum young " SIZE_FORMAT "  Initial young " SIZE_FORMAT "  Maximum young " SIZE_FORMAT,

                      _min_young_size, _initial_young_size, _max_young_size);

  // At this point the minimum, initial and maximum sizes

  // of the overall heap and of the young generation have been determined.

  // The maximum old size can be determined from the maximum young

  // and maximum heap size since no explicit flags exist

  // for setting the old generation maximum.

  _max_old_size = MAX2(_max_heap_byte_size - _max_young_size, _gen_alignment);

  // If no explicit command line flag has been set for the

  // old generation size, use what is left.

  if (!FLAG_IS_CMDLINE(OldSize)) {

    // The user has not specified any value but the ergonomics

    // may have chosen a value (which may or may not be consistent

    // with the overall heap size).  In either case make

    // the minimum, maximum and initial sizes consistent

    // with the young sizes and the overall heap sizes.

    _min_old_size = _gen_alignment;

    _initial_old_size = MIN2(_max_old_size, MAX2(_initial_heap_byte_size - _initial_young_size, _min_old_size));

    // _max_old_size has already been made consistent above.

  } else {

    // OldSize has been explicitly set on the command line. Use it

    // for the initial size but make sure the minimum allow a young

    // generation to fit as well.

    // If the user has explicitly set an OldSize that is inconsistent

    // with other command line flags, issue a warning.

    // The generation minimums and the overall heap minimum should

    // be within one generation alignment.

    if (_initial_old_size > _max_old_size) {

      log_warning(gc, ergo)("Inconsistency between maximum heap size and maximum "

                            "generation sizes: using maximum heap = " SIZE_FORMAT

                            ", -XX:OldSize flag is being ignored",

                            _max_heap_byte_size);

      _initial_old_size = _max_old_size;