/*

 * Copyright (c) 2003, 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

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 */

#include "precompiled.hpp"

#include "gc/parallel/asPSYoungGen.hpp"

#include "gc/parallel/parallelScavengeHeap.hpp"

#include "gc/parallel/psMarkSweepDecorator.hpp"

#include "gc/parallel/psScavenge.inline.hpp"

#include "gc/parallel/psYoungGen.hpp"

#include "gc/shared/gcUtil.hpp"

#include "gc/shared/genArguments.hpp"

#include "gc/shared/spaceDecorator.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

#include "utilities/align.hpp"

ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,

                           size_t minimum_byte_size,

                           size_t byte_size_limit) :

  PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),

  _gen_size_limit(byte_size_limit) {

}

ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,

                           size_t init_byte_size,

                           size_t minimum_byte_size,

                           size_t byte_size_limit) :

  //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),

  PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),

  _gen_size_limit(byte_size_limit) {

  assert(vs->committed_size() == init_byte_size, "Cannot replace with");

  _virtual_space = vs;

}

void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,

                                            size_t alignment) {

  assert(_init_gen_size != 0, "Should have a finite size");

  _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);

  if (!_virtual_space->expand_by(_init_gen_size)) {

    vm_exit_during_initialization("Could not reserve enough space for "

                                  "object heap");

  }

}

void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {

  initialize_virtual_space(rs, alignment);

  initialize_work();

}

size_t ASPSYoungGen::available_for_expansion() {

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

  assert((gen_size_limit() >= current_committed_size),

    "generation size limit is wrong");

  size_t result =  gen_size_limit() - current_committed_size;

  size_t result_aligned = align_down(result, GenAlignment);

  return result_aligned;

}

// Return the number of bytes the young gen is willing give up.

//

// Future implementations could check the survivors and if to_space is in the

// right place (below from_space), take a chunk from to_space.

size_t ASPSYoungGen::available_for_contraction() {

  size_t uncommitted_bytes = virtual_space()->uncommitted_size();

  if (uncommitted_bytes != 0) {

    return uncommitted_bytes;

  }

  if (eden_space()->is_empty()) {

    // Respect the minimum size for eden and for the young gen as a whole.

    ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

    const size_t eden_alignment = SpaceAlignment;

    assert(eden_space()->capacity_in_bytes() >= eden_alignment,

      "Alignment is wrong");

    size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;

    eden_avail = align_down(eden_avail, GenAlignment);

    assert(virtual_space()->committed_size() >= min_gen_size(),

      "minimum gen size is wrong");

    size_t gen_avail = virtual_space()->committed_size() - min_gen_size();

    assert(virtual_space()->is_aligned(gen_avail), "not aligned");

    const size_t max_contraction = MIN2(eden_avail, gen_avail);

    // See comment for ASPSOldGen::available_for_contraction()

    // for reasons the "increment" fraction is used.

    PSAdaptiveSizePolicy* policy = heap->size_policy();

    size_t result = policy->eden_increment_aligned_down(max_contraction);

    size_t result_aligned = align_down(result, GenAlignment);

    log_trace(gc, ergo)("ASPSYoungGen::available_for_contraction: " SIZE_FORMAT " K", result_aligned/K);

    log_trace(gc, ergo)("  max_contraction " SIZE_FORMAT " K", max_contraction/K);

    log_trace(gc, ergo)("  eden_avail " SIZE_FORMAT " K", eden_avail/K);

    log_trace(gc, ergo)("  gen_avail " SIZE_FORMAT " K", gen_avail/K);

    return result_aligned;

  }

  return 0;

}

// The current implementation only considers to the end of eden.

// If to_space is below from_space, to_space is not considered.

// to_space can be.

size_t ASPSYoungGen::available_to_live() {

  const size_t alignment = SpaceAlignment;

  // Include any space that is committed but is not in eden.

  size_t available = pointer_delta(eden_space()->bottom(),

                                   virtual_space()->low(),

                                   sizeof(char));

  const size_t eden_capacity = eden_space()->capacity_in_bytes();

  if (eden_space()->is_empty() && eden_capacity > alignment) {

    available += eden_capacity - alignment;

  }

  return available;

}

// Similar to PSYoungGen::resize_generation() but

//  allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size

//  expands at the low end of the virtual space

//  moves the boundary between the generations in order to expand

//  some additional diagnostics

// If no additional changes are required, this can be deleted

// and the changes factored back into PSYoungGen::resize_generation().

bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {

  const size_t alignment = virtual_space()->alignment();

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

  bool size_changed = false;

  // There used to be a guarantee here that

  //   (eden_size + 2*survivor_size)  <= _max_gen_size

  // This requirement is enforced by the calculation of desired_size

  // below.  It may not be true on entry since the size of the

  // eden_size is no bounded by the generation size.

  assert(max_size() == reserved().byte_size(), "max gen size problem?");

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

         "just checking");

  // Adjust new generation size

  const size_t eden_plus_survivors =

    align_up(eden_size + 2 * survivor_size, alignment);

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

  if (desired_size > orig_size) {

    // Grow the generation

    size_t change = desired_size - orig_size;

    HeapWord* prev_low = (HeapWord*) virtual_space()->low();

    if (!virtual_space()->expand_by(change)) {

      return false;

    }

    if (ZapUnusedHeapArea) {

      // Mangle newly committed space immediately because it

      // can be done here more simply that after the new

      // spaces have been computed.

      HeapWord* new_low = (HeapWord*) virtual_space()->low();

      assert(new_low < prev_low, "Did not grow");

      MemRegion mangle_region(new_low, prev_low);

      SpaceMangler::mangle_region(mangle_region);

    }

    size_changed = true;

  } else if (desired_size < orig_size) {

    size_t desired_change = orig_size - desired_size;

    // How much is available for shrinking.

    size_t available_bytes = limit_gen_shrink(desired_change);

    size_t change = MIN2(desired_change, available_bytes);

    virtual_space()->shrink_by(change);

    size_changed = true;

  } else {

    if (orig_size == gen_size_limit()) {

      log_trace(gc)("ASPSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);

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

      log_trace(gc)("ASPSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);

    }

  }

  if (size_changed) {

    reset_after_change();

    log_trace(gc)("ASPSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",

                  orig_size/K, virtual_space()->committed_size()/K);

  }

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

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

  return true;

}

// Similar to PSYoungGen::resize_spaces() but

//  eden always starts at the low end of the committed virtual space

//  current implementation does not allow holes between the spaces

//  _young_generation_boundary has to be reset because it changes.

//  so additional verification

void ASPSYoungGen::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");

  space_invariants();

  // We require eden and to space to be empty

  if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {

    return;

  }

  log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: "

                      SIZE_FORMAT

                      ", requested_survivor_size: " SIZE_FORMAT ")",

                      requested_eden_size, requested_survivor_size);

  log_trace(gc, ergo)("    eden: [" PTR_FORMAT ".." PTR_FORMAT ") "

                      SIZE_FORMAT,

                      p2i(eden_space()->bottom()),

                      p2i(eden_space()->end()),

                      pointer_delta(eden_space()->end(), eden_space()->bottom(), sizeof(char)));

  log_trace(gc, ergo)("    from: [" PTR_FORMAT ".." PTR_FORMAT ") "

                      SIZE_FORMAT,

                      p2i(from_space()->bottom()),

                      p2i(from_space()->end()),

                      pointer_delta(from_space()->end(), from_space()->bottom(), sizeof(char)));

  log_trace(gc, ergo)("      to: [" PTR_FORMAT ".." PTR_FORMAT ") "

                      SIZE_FORMAT,

                      p2i(to_space()->bottom()),

                      p2i(to_space()->end()),

                      pointer_delta(  to_space()->end(), to_space()->bottom(), sizeof(char)));

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

  if (requested_survivor_size == to_space()->capacity_in_bytes() &&

      requested_survivor_size == from_space()->capacity_in_bytes() &&

      requested_eden_size == eden_space()->capacity_in_bytes()) {

    log_trace(gc, ergo)("    capacities are the right sizes, returning");

    return;

  }

  char* eden_start = (char*)virtual_space()->low();

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

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

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

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

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

  assert(eden_start < from_start, "Cannot push into from_space");

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

  const bool maintain_minimum =

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

  bool eden_from_to_order = from_start < to_start;

  // Check whether from space is below to space

  if (eden_from_to_order) {

    // Eden, from, to

    log_trace(gc, ergo)("  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_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_space()->end()) {

      // Calculate the minimum offset possible for from_end

      size_t from_size =

        pointer_delta(from_space()->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 = SpaceAlignment;

      } else {

        from_size = align_up(from_size, SpaceAlignment);

      }

      from_end = from_start + from_size;

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

      guarantee(from_end <= (char*)from_space()->end(),

        "from_end moved to the right");

      // Now update to_start with the new from_end

      to_start = MAX2(from_end, to_start);

    }

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

    log_trace(gc, ergo)("    [eden_start .. eden_end): "

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

                        p2i(eden_start),

                        p2i(eden_end),

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

    log_trace(gc, ergo)("    [from_start .. from_end): "

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

                        p2i(from_start),

                        p2i(from_end),

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

    log_trace(gc, ergo)("    [  to_start ..   to_end): "

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

                        p2i(to_start),

                        p2i(to_end),

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

  } else {

    // Eden, to, from

    log_trace(gc, ergo)("  Eden, to, from:");

    // To space gets priority over eden resizing. Note that we position

    // to space as if we were able to resize from space, even though from

    // space is not modified.

    // Giving eden priority was tried and gave poorer performance.

    to_end   = (char*)pointer_delta(virtual_space()->high(),

                                    (char*)requested_survivor_size,

                                    sizeof(char));

    to_end   = MIN2(to_end, from_start);

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

                                    sizeof(char));

    // if the space sizes are to be increased by several times then

    // 'to_start' will point beyond the young generation. In this case

    // 'to_start' should be adjusted.

    to_start = MAX2(to_start, eden_start + SpaceAlignment);

    // Compute how big eden can be, then adjust end.

    // See  comments above on calculating eden_end.

    size_t eden_size;

    if (maintain_minimum) {

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

    } else {

      eden_size = MIN2(requested_eden_size,

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

    }

    eden_end = eden_start + eden_size;

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

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

    eden_end = MAX2(eden_end, eden_start + SpaceAlignment);

    to_start = MAX2(to_start, eden_end);

    log_trace(gc, ergo)("    [eden_start .. eden_end): "

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

                        p2i(eden_start),

                        p2i(eden_end),

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

    log_trace(gc, ergo)("    [  to_start ..   to_end): "

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

                        p2i(to_start),

                        p2i(to_end),

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

    log_trace(gc, ergo)("    [from_start .. from_end): "

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

                        p2i(from_start),

                        p2i(from_end),

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

  }

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

            "from start moved to the right");

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

            "from end moved into live data");

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

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

  assert(is_object_aligned(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"!

  DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)

  // For logging block  below

  size_t old_from = from_space()->capacity_in_bytes();

  size_t old_to   = to_space()->capacity_in_bytes();

  if (ZapUnusedHeapArea) {

    // NUMA is a special case because a numa space is not mangled

    // in order to not prematurely bind its address to memory to

    // the wrong memory (i.e., don't want the GC thread to first

    // touch the memory).  The survivor spaces are not numa

    // spaces and are mangled.

    if (UseNUMA) {

      if (eden_from_to_order) {

        mangle_survivors(from_space(), fromMR, to_space(), toMR);

      } else {

        mangle_survivors(to_space(), toMR, from_space(), fromMR);

      }

    }

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

    // the spaces are already mangled.

    // The spaces should be correctly mangled at this point so

    // do some checking here. Note that they are not being mangled

    // in the calls to initialize().

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

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

    // covered by another space and a failure of the check may

    // not correctly indicate which space is not properly mangled.

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

    eden_space()->check_mangled_unused_area(limit);

    from_space()->check_mangled_unused_area(limit);

      to_space()->check_mangled_unused_area(limit);

  }

  // When an existing space is being initialized, it is not

  // mangled because the space has been previously mangled.

  eden_space()->initialize(edenMR,

                           SpaceDecorator::Clear,

                           SpaceDecorator::DontMangle);

    to_space()->initialize(toMR,

                           SpaceDecorator::Clear,

                           SpaceDecorator::DontMangle);

  from_space()->initialize(fromMR,

                           SpaceDecorator::DontClear,

                           SpaceDecorator::DontMangle);

  PSScavenge::set_young_generation_boundary(eden_space()->bottom());

  assert(from_space()->top() == old_from_top, "from top changed!");

  log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: "

                "collection: %d "

                "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "

                "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",

                ParallelScavengeHeap::heap()->total_collections(),

                old_from, old_to,

                from_space()->capacity_in_bytes(),

                to_space()->capacity_in_bytes());

    space_invariants();

}

void ASPSYoungGen::reset_after_change() {

  assert_locked_or_safepoint(Heap_lock);

  _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),

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

  PSScavenge::set_subject_to_discovery_span(_reserved);

  HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();

  HeapWord* eden_bottom = eden_space()->bottom();

  if (new_eden_bottom != eden_bottom) {

    MemRegion eden_mr(new_eden_bottom, eden_space()->end());

    eden_space()->initialize(eden_mr,

                             SpaceDecorator::Clear,

                             SpaceDecorator::Mangle);

    PSScavenge::set_young_generation_boundary(eden_space()->bottom());

  }

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

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

  ParallelScavengeHeap::heap()->barrier_set()->card_table()->resize_covered_region(cmr);