/*

 * 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

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 */

#include "precompiled.hpp"

#include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"

#include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"

#include "gc_implementation/parNew/asParNewGeneration.hpp"

#include "gc_implementation/parNew/parNewGeneration.hpp"

#include "gc_implementation/shared/markSweep.inline.hpp"

#include "gc_implementation/shared/spaceDecorator.hpp"

#include "memory/defNewGeneration.inline.hpp"

#include "memory/referencePolicy.hpp"

#include "oops/markOop.inline.hpp"

#include "oops/oop.pcgc.inline.hpp"

ASParNewGeneration::ASParNewGeneration(ReservedSpace rs,

                                       size_t initial_byte_size,

                                       size_t min_byte_size,

                                       int level) :

  ParNewGeneration(rs, initial_byte_size, level),

  _min_gen_size(min_byte_size) {}

const char* ASParNewGeneration::name() const {

  return "adaptive size par new generation";

}

void ASParNewGeneration::adjust_desired_tenuring_threshold() {

  assert(UseAdaptiveSizePolicy,

    "Should only be used with UseAdaptiveSizePolicy");

}

void ASParNewGeneration::resize(size_t eden_size, size_t survivor_size) {

  // Resize the generation if needed. If the generation resize

  // reports false, do not attempt to resize the spaces.

  if (resize_generation(eden_size, survivor_size)) {

    // Then we lay out the spaces inside the generation

    resize_spaces(eden_size, survivor_size);

    space_invariants();

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("Young generation size: "

        "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT

        " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT

        " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,

        eden_size, survivor_size, used(), capacity(),

        max_gen_size(), min_gen_size());

    }

  }

}

size_t ASParNewGeneration::available_to_min_gen() {

  assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");

  return virtual_space()->committed_size() - min_gen_size();

}

// This method assumes that from-space has live data and that

// any shrinkage of the young gen is limited by location of

// from-space.

size_t ASParNewGeneration::available_to_live() const {

#undef SHRINKS_AT_END_OF_EDEN

#ifdef SHRINKS_AT_END_OF_EDEN

  size_t delta_in_survivor = 0;

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  const size_t space_alignment = heap->intra_heap_alignment();

  const size_t gen_alignment = heap->object_heap_alignment();

  MutableSpace* space_shrinking = NULL;

  if (from_space()->end() > to_space()->end()) {

    space_shrinking = from_space();

  } else {

    space_shrinking = to_space();

  }

  // Include any space that is committed but not included in

  // the survivor spaces.

  assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),

    "Survivor space beyond high end");

  size_t unused_committed = pointer_delta(virtual_space()->high(),

    space_shrinking->end(), sizeof(char));

  if (space_shrinking->is_empty()) {

    // Don't let the space shrink to 0

    assert(space_shrinking->capacity_in_bytes() >= space_alignment,

      "Space is too small");

    delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;

  } else {

    delta_in_survivor = pointer_delta(space_shrinking->end(),

                                      space_shrinking->top(),

                                      sizeof(char));

  }

  size_t delta_in_bytes = unused_committed + delta_in_survivor;

  delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment);

  return delta_in_bytes;

#else

  // The only space available for shrinking is in to-space if it

  // is above from-space.

  if (to()->bottom() > from()->bottom()) {

    const size_t alignment = os::vm_page_size();

    if (to()->capacity() < alignment) {

      return 0;

    } else {

      return to()->capacity() - alignment;

    }

  } else {

    return 0;

  }

#endif

}

// Return the number of bytes available for resizing down the young

// generation.  This is the minimum of

//      input "bytes"

//      bytes to the minimum young gen size

//      bytes to the size currently being used + some small extra

size_t ASParNewGeneration::limit_gen_shrink (size_t bytes) {

  // Allow shrinkage into the current eden but keep eden large enough

  // to maintain the minimum young gen size

  bytes = MIN3(bytes, available_to_min_gen(), available_to_live());

  return align_size_down(bytes, os::vm_page_size());

}

// Note that the the alignment used is the OS page size as

// opposed to an alignment associated with the virtual space

// (as is done in the ASPSYoungGen/ASPSOldGen)

bool ASParNewGeneration::resize_generation(size_t eden_size,

                                           size_t survivor_size) {

  const size_t alignment = os::vm_page_size();

  size_t orig_size = virtual_space()->committed_size();

  bool size_changed = false;

  // There used to be this guarantee there.

  // guarantee ((eden_size + 2*survivor_size)  <= _max_gen_size, "incorrect input arguments");

  // Code below forces this requirement.  In addition the desired eden

  // size and desired survivor sizes are desired goals and may

  // exceed the total generation size.

  assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(),

    "just checking");

  // Adjust new generation size

  const size_t eden_plus_survivors =

          align_size_up(eden_size + 2 * survivor_size, alignment);

  size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_gen_size()),

                             min_gen_size());

  assert(desired_size <= max_gen_size(), "just checking");

  if (desired_size > orig_size) {

    // Grow the generation

    size_t change = desired_size - orig_size;

    assert(change % alignment == 0, "just checking");

    if (expand(change)) {

      return false; // Error if we fail to resize!

    }

    size_changed = true;

  } else if (desired_size < orig_size) {

    size_t desired_change = orig_size - desired_size;

    assert(desired_change % alignment == 0, "just checking");

    desired_change = limit_gen_shrink(desired_change);

    if (desired_change > 0) {

      virtual_space()->shrink_by(desired_change);

      reset_survivors_after_shrink();

      size_changed = true;

    }

  } else {

    if (Verbose && PrintGC) {

      if (orig_size == max_gen_size()) {

        gclog_or_tty->print_cr("ASParNew generation size at maximum: "

          SIZE_FORMAT "K", orig_size/K);

      } else if (orig_size == min_gen_size()) {

        gclog_or_tty->print_cr("ASParNew generation size at minium: "

          SIZE_FORMAT "K", orig_size/K);

      }

    }

  }

  if (size_changed) {

    MemRegion cmr((HeapWord*)virtual_space()->low(),

                  (HeapWord*)virtual_space()->high());

    GenCollectedHeap::heap()->barrier_set()->resize_covered_region(cmr);

    if (Verbose && PrintGC) {

      size_t current_size  = virtual_space()->committed_size();

      gclog_or_tty->print_cr("ASParNew generation size changed: "

                             SIZE_FORMAT "K->" SIZE_FORMAT "K",

                             orig_size/K, current_size/K);

    }

  }

  guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||

            virtual_space()->committed_size() == max_gen_size(), "Sanity");

  return true;

}

void ASParNewGeneration::reset_survivors_after_shrink() {

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  HeapWord* new_end = (HeapWord*)virtual_space()->high();

  if (from()->end() > to()->end()) {

    assert(new_end >= from()->end(), "Shrinking past from-space");

  } else {

    assert(new_end >= to()->bottom(), "Shrink was too large");

    // Was there a shrink of the survivor space?

    if (new_end < to()->end()) {

      MemRegion mr(to()->bottom(), new_end);

      to()->initialize(mr,

                       SpaceDecorator::DontClear,

                       SpaceDecorator::DontMangle);

    }

  }

}

void ASParNewGeneration::resize_spaces(size_t requested_eden_size,

                                       size_t requested_survivor_size) {

  assert(UseAdaptiveSizePolicy, "sanity check");

  assert(requested_eden_size > 0  && requested_survivor_size > 0,

         "just checking");

  CollectedHeap* heap = Universe::heap();

  assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Sanity");

  // We require eden and to space to be empty

  if ((!eden()->is_empty()) || (!to()->is_empty())) {

    return;

  }

  size_t cur_eden_size = eden()->capacity();

  if (PrintAdaptiveSizePolicy && Verbose) {

    gclog_or_tty->print_cr("ASParNew::resize_spaces(requested_eden_size: "

                  SIZE_FORMAT

                  ", requested_survivor_size: " SIZE_FORMAT ")",

                  requested_eden_size, requested_survivor_size);

    gclog_or_tty->print_cr("    eden: [" PTR_FORMAT ".." PTR_FORMAT ") "

                  SIZE_FORMAT,

                  pointer_delta(eden()->end(),

                                eden()->bottom(),

                                sizeof(char)));

    gclog_or_tty->print_cr("    from: [" PTR_FORMAT ".." PTR_FORMAT ") "

                  SIZE_FORMAT,

                  pointer_delta(from()->end(),

                                from()->bottom(),

                                sizeof(char)));

    gclog_or_tty->print_cr("      to: [" PTR_FORMAT ".." PTR_FORMAT ") "

                  SIZE_FORMAT,

                  pointer_delta(  to()->end(),

                                  to()->bottom(),

                                  sizeof(char)));

  }

  // There's nothing to do if the new sizes are the same as the current

  if (requested_survivor_size == to()->capacity() &&

      requested_survivor_size == from()->capacity() &&

      requested_eden_size == eden()->capacity()) {

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("    capacities are the right sizes, returning");

    }

    return;

  }

  char* eden_start = (char*)eden()->bottom();

  char* eden_end   = (char*)eden()->end();

  char* from_start = (char*)from()->bottom();

  char* from_end   = (char*)from()->end();

  char* to_start   = (char*)to()->bottom();

  char* to_end     = (char*)to()->end();

  const size_t alignment = os::vm_page_size();

  const bool maintain_minimum =

    (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();

  // Check whether from space is below to space

  if (from_start < to_start) {

    // Eden, from, to

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("  Eden, from, to:");

    }

    // Set eden

    // "requested_eden_size" is a goal for the size of eden

    // and may not be attainable.  "eden_size" below is

    // calculated based on the location of from-space and

    // the goal for the size of eden.  from-space is

    // fixed in place because it contains live data.

    // The calculation is done this way to avoid 32bit

    // overflow (i.e., eden_start + requested_eden_size

    // may too large for representation in 32bits).

    size_t eden_size;

    if (maintain_minimum) {

      // Only make eden larger than the requested size if

      // the minimum size of the generation has to be maintained.

      // This could be done in general but policy at a higher

      // level is determining a requested size for eden and that

      // should be honored unless there is a fundamental reason.

      eden_size = pointer_delta(from_start,

                                eden_start,

                                sizeof(char));

    } else {

      eden_size = MIN2(requested_eden_size,

                       pointer_delta(from_start, eden_start, sizeof(char)));

    }

    eden_size = align_size_down(eden_size, alignment);

    eden_end = eden_start + eden_size;

    assert(eden_end >= eden_start, "addition overflowed");

    // To may resize into from space as long as it is clear of live data.

    // From space must remain page aligned, though, so we need to do some

    // extra calculations.

    // First calculate an optimal to-space

    to_end   = (char*)virtual_space()->high();

    to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,

                                    sizeof(char));

    // Does the optimal to-space overlap from-space?

    if (to_start < (char*)from()->end()) {

      // Calculate the minimum offset possible for from_end

      size_t from_size = pointer_delta(from()->top(), from_start, sizeof(char));

      // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!

      if (from_size == 0) {

        from_size = alignment;

      } else {

        from_size = align_size_up(from_size, alignment);

      }

      from_end = from_start + from_size;

      assert(from_end > from_start, "addition overflow or from_size problem");

      guarantee(from_end <= (char*)from()->end(), "from_end moved to the right");

      // Now update to_start with the new from_end

      to_start = MAX2(from_end, to_start);

    } else {

      // If shrinking, move to-space down to abut the end of from-space

      // so that shrinking will move to-space down.  If not shrinking

      // to-space is moving up to allow for growth on the next expansion.

      if (requested_eden_size <= cur_eden_size) {

        to_start = from_end;

        if (to_start + requested_survivor_size > to_start) {

          to_end = to_start + requested_survivor_size;

        }

      }

      // else leave to_end pointing to the high end of the virtual space.

    }

    guarantee(to_start != to_end, "to space is zero sized");

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("    [eden_start .. eden_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(eden_end, eden_start, sizeof(char)));

      gclog_or_tty->print_cr("    [from_start .. from_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(from_end, from_start, sizeof(char)));

      gclog_or_tty->print_cr("    [  to_start ..   to_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(  to_end,   to_start, sizeof(char)));

    }

  } else {

    // Eden, to, from

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("  Eden, to, from:");

    }

    // Calculate the to-space boundaries based on

    // the start of from-space.

    to_end = from_start;

    to_start = (char*)pointer_delta(from_start,

                                    (char*)requested_survivor_size,

                                    sizeof(char));

    // Calculate the ideal eden boundaries.

    // eden_end is already at the bottom of the generation

    assert(eden_start == virtual_space()->low(),

      "Eden is not starting at the low end of the virtual space");

    if (eden_start + requested_eden_size >= eden_start) {

      eden_end = eden_start + requested_eden_size;

    } else {

      eden_end = to_start;

    }

    // Does eden intrude into to-space?  to-space

    // gets priority but eden is not allowed to shrink

    // to 0.

    if (eden_end > to_start) {

      eden_end = to_start;

    }

    // Don't let eden shrink down to 0 or less.

    eden_end = MAX2(eden_end, eden_start + alignment);

    assert(eden_start + alignment >= eden_start, "Overflow");

    size_t eden_size;

    if (maintain_minimum) {

      // Use all the space available.

      eden_end = MAX2(eden_end, to_start);

      eden_size = pointer_delta(eden_end, eden_start, sizeof(char));

      eden_size = MIN2(eden_size, cur_eden_size);

    } else {

      eden_size = pointer_delta(eden_end, eden_start, sizeof(char));

    }

    eden_size = align_size_down(eden_size, alignment);

    assert(maintain_minimum || eden_size <= requested_eden_size,

      "Eden size is too large");

    assert(eden_size >= alignment, "Eden size is too small");

    eden_end = eden_start + eden_size;

    // Move to-space down to eden.

    if (requested_eden_size < cur_eden_size) {

      to_start = eden_end;

      if (to_start + requested_survivor_size > to_start) {

        to_end = MIN2(from_start, to_start + requested_survivor_size);

      } else {

        to_end = from_start;

      }

    }

    // eden_end may have moved so again make sure

    // the to-space and eden don't overlap.

    to_start = MAX2(eden_end, to_start);

    // from-space

    size_t from_used = from()->used();

    if (requested_survivor_size > from_used) {

      if (from_start + requested_survivor_size >= from_start) {

        from_end = from_start + requested_survivor_size;

      }

      if (from_end > virtual_space()->high()) {

        from_end = virtual_space()->high();

      }

    }

    assert(to_start >= eden_end, "to-space should be above eden");

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print_cr("    [eden_start .. eden_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(eden_end, eden_start, sizeof(char)));

      gclog_or_tty->print_cr("    [  to_start ..   to_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(  to_end,   to_start, sizeof(char)));

      gclog_or_tty->print_cr("    [from_start .. from_end): "

                    "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                    pointer_delta(from_end, from_start, sizeof(char)));

    }

  }

  guarantee((HeapWord*)from_start <= from()->bottom(),

            "from start moved to the right");

  guarantee((HeapWord*)from_end >= from()->top(),

            "from end moved into live data");

  assert(is_object_aligned((intptr_t)eden_start), "checking alignment");

  assert(is_object_aligned((intptr_t)from_start), "checking alignment");

  assert(is_object_aligned((intptr_t)to_start), "checking alignment");

  MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);

  MemRegion toMR  ((HeapWord*)to_start,   (HeapWord*)to_end);

  MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);

  // Let's make sure the call to initialize doesn't reset "top"!

  HeapWord* old_from_top = from()->top();

  // For PrintAdaptiveSizePolicy block  below

  size_t old_from = from()->capacity();

  size_t old_to   = to()->capacity();

  // If not clearing the spaces, do some checking to verify that

  // the spaces are already mangled.

  // Must check mangling before the spaces are reshaped.  Otherwise,

  // the bottom or end of one space may have moved into another

  // a failure of the check may not correctly indicate which space

  // is not properly mangled.

  if (ZapUnusedHeapArea) {

    HeapWord* limit = (HeapWord*) virtual_space()->high();

    eden()->check_mangled_unused_area(limit);

    from()->check_mangled_unused_area(limit);

      to()->check_mangled_unused_area(limit);