/*

 * Copyright (c) 2001, 2012, 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_implementation/shared/collectorCounters.hpp"

#include "gc_implementation/shared/parGCAllocBuffer.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/blockOffsetTable.inline.hpp"

#include "memory/generation.inline.hpp"

#include "memory/generationSpec.hpp"

#include "memory/space.hpp"

#include "memory/tenuredGeneration.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

TenuredGeneration::TenuredGeneration(ReservedSpace rs,

                                     size_t initial_byte_size, int level,

                                     GenRemSet* remset) :

  OneContigSpaceCardGeneration(rs, initial_byte_size,

                               MinHeapDeltaBytes, level, remset, NULL)

{

  HeapWord* bottom = (HeapWord*) _virtual_space.low();

  HeapWord* end    = (HeapWord*) _virtual_space.high();

  _the_space  = new TenuredSpace(_bts, MemRegion(bottom, end));

  _the_space->reset_saved_mark();

  _shrink_factor = 0;

  _capacity_at_prologue = 0;

  _gc_stats = new GCStats();

  // initialize performance counters

  const char* gen_name = "old";

  // Generation Counters -- generation 1, 1 subspace

  _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space);

  _gc_counters = new CollectorCounters("MSC", 1);

  _space_counters = new CSpaceCounters(gen_name, 0,

                                       _virtual_space.reserved_size(),

                                       _the_space, _gen_counters);

#ifndef SERIALGC

    typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;

    _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,

                                      ParallelGCThreads, mtGC);

    if (_alloc_buffers == NULL)

      vm_exit_during_initialization("Could not allocate alloc_buffers");

    for (uint i = 0; i < ParallelGCThreads; i++) {

      _alloc_buffers[i] =

        new ParGCAllocBufferWithBOT(OldPLABSize, _bts);

      if (_alloc_buffers[i] == NULL)

        vm_exit_during_initialization("Could not allocate alloc_buffers");

    }

  } else {

    _alloc_buffers = NULL;

  }

#endif // SERIALGC

}

const char* TenuredGeneration::name() const {

  return "tenured generation";

}

void TenuredGeneration::compute_new_size() {

  assert(_shrink_factor <= 100, "invalid shrink factor");

  size_t current_shrink_factor = _shrink_factor;

  _shrink_factor = 0;

  // We don't have floating point command-line arguments

  // Note:  argument processing ensures that MinHeapFreeRatio < 100.

  const double minimum_free_percentage = MinHeapFreeRatio / 100.0;

  const double maximum_used_percentage = 1.0 - minimum_free_percentage;

  // Compute some numbers about the state of the heap.

  const size_t used_after_gc = used();

  const size_t capacity_after_gc = capacity();

  const double min_tmp = used_after_gc / maximum_used_percentage;

  size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));

  // Don't shrink less than the initial generation size

  minimum_desired_capacity = MAX2(minimum_desired_capacity,

                                  spec()->init_size());

  assert(used_after_gc <= minimum_desired_capacity, "sanity check");

  if (PrintGC && Verbose) {

    const size_t free_after_gc = free();

    const double free_percentage = ((double)free_after_gc) / capacity_after_gc;

    gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");

    gclog_or_tty->print_cr("  "

                  "  minimum_free_percentage: %6.2f"

                  "  maximum_used_percentage: %6.2f",

                  minimum_free_percentage,

                  maximum_used_percentage);

    gclog_or_tty->print_cr("  "

                  "   free_after_gc   : %6.1fK"

                  "   used_after_gc   : %6.1fK"

                  "   capacity_after_gc   : %6.1fK",

                  free_after_gc / (double) K,

                  used_after_gc / (double) K,

                  capacity_after_gc / (double) K);

    gclog_or_tty->print_cr("  "

                  "   free_percentage: %6.2f",

                  free_percentage);

  }

  if (capacity_after_gc < minimum_desired_capacity) {

    // If we have less free space than we want then expand

    size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;

    // Don't expand unless it's significant

    if (expand_bytes >= _min_heap_delta_bytes) {

      expand(expand_bytes, 0); // safe if expansion fails

    }

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("    expanding:"

                    "  minimum_desired_capacity: %6.1fK"

                    "  expand_bytes: %6.1fK"

                    "  _min_heap_delta_bytes: %6.1fK",

                    minimum_desired_capacity / (double) K,

                    expand_bytes / (double) K,

                    _min_heap_delta_bytes / (double) K);

    }

    return;

  }

  // No expansion, now see if we want to shrink

  size_t shrink_bytes = 0;

  // We would never want to shrink more than this

  size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;

  if (MaxHeapFreeRatio < 100) {

    const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;

    const double minimum_used_percentage = 1.0 - maximum_free_percentage;

    const double max_tmp = used_after_gc / minimum_used_percentage;

    size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));

    maximum_desired_capacity = MAX2(maximum_desired_capacity,

                                    spec()->init_size());

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("  "

                             "  maximum_free_percentage: %6.2f"

                             "  minimum_used_percentage: %6.2f",

                             maximum_free_percentage,

                             minimum_used_percentage);

      gclog_or_tty->print_cr("  "

                             "  _capacity_at_prologue: %6.1fK"

                             "  minimum_desired_capacity: %6.1fK"

                             "  maximum_desired_capacity: %6.1fK",

                             _capacity_at_prologue / (double) K,

                             minimum_desired_capacity / (double) K,

                             maximum_desired_capacity / (double) K);

    }

    assert(minimum_desired_capacity <= maximum_desired_capacity,

           "sanity check");

    if (capacity_after_gc > maximum_desired_capacity) {

      // Capacity too large, compute shrinking size

      shrink_bytes = capacity_after_gc - maximum_desired_capacity;

      // We don't want shrink all the way back to initSize if people call

      // System.gc(), because some programs do that between "phases" and then

      // we'd just have to grow the heap up again for the next phase.  So we

      // damp the shrinking: 0% on the first call, 10% on the second call, 40%

      // on the third call, and 100% by the fourth call.  But if we recompute

      // size without shrinking, it goes back to 0%.

      shrink_bytes = shrink_bytes / 100 * current_shrink_factor;

      assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");

      if (current_shrink_factor == 0) {

        _shrink_factor = 10;

      } else {

        _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);

      }

      if (PrintGC && Verbose) {

        gclog_or_tty->print_cr("  "

                      "  shrinking:"

                      "  initSize: %.1fK"

                      "  maximum_desired_capacity: %.1fK",

                      spec()->init_size() / (double) K,

                      maximum_desired_capacity / (double) K);

        gclog_or_tty->print_cr("  "

                      "  shrink_bytes: %.1fK"

                      "  current_shrink_factor: %d"

                      "  new shrink factor: %d"

                      "  _min_heap_delta_bytes: %.1fK",

                      shrink_bytes / (double) K,

                      current_shrink_factor,

                      _shrink_factor,

                      _min_heap_delta_bytes / (double) K);

      }

    }

  }

  if (capacity_after_gc > _capacity_at_prologue) {

    // We might have expanded for promotions, in which case we might want to

    // take back that expansion if there's room after GC.  That keeps us from

    // stretching the heap with promotions when there's plenty of room.

    size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;

    expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);

    // We have two shrinking computations, take the largest

    shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);

    assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("  "

                             "  aggressive shrinking:"

                             "  _capacity_at_prologue: %.1fK"

                             "  capacity_after_gc: %.1fK"

                             "  expansion_for_promotion: %.1fK"

                             "  shrink_bytes: %.1fK",

                             capacity_after_gc / (double) K,

                             _capacity_at_prologue / (double) K,

                             expansion_for_promotion / (double) K,

                             shrink_bytes / (double) K);

    }

  }

  // Don't shrink unless it's significant

  if (shrink_bytes >= _min_heap_delta_bytes) {

    shrink(shrink_bytes);

  }

  assert(used() == used_after_gc && used_after_gc <= capacity(),

         "sanity check");

}

void TenuredGeneration::gc_prologue(bool full) {

  _capacity_at_prologue = capacity();

  _used_at_prologue = used();

  if (VerifyBeforeGC) {

    verify_alloc_buffers_clean();

  }

}

void TenuredGeneration::gc_epilogue(bool full) {

  if (VerifyAfterGC) {

    verify_alloc_buffers_clean();

  }

  OneContigSpaceCardGeneration::gc_epilogue(full);

}

bool TenuredGeneration::should_collect(bool  full,

                                       size_t size,

                                       bool   is_tlab) {

  // This should be one big conditional or (||), but I want to be able to tell

  // why it returns what it returns (without re-evaluating the conditionals

  // in case they aren't idempotent), so I'm doing it this way.

  // DeMorgan says it's okay.

  bool result = false;

  if (!result && full) {

    result = true;

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"

                    " full");

    }

  }

  if (!result && should_allocate(size, is_tlab)) {

    result = true;

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"

                    " should_allocate(" SIZE_FORMAT ")",

                    size);

    }

  }

  // If we don't have very much free space.

  // XXX: 10000 should be a percentage of the capacity!!!

  if (!result && free() < 10000) {

    result = true;

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"

                    " free(): " SIZE_FORMAT,

                    free());

    }

  }

  // If we had to expand to accomodate promotions from younger generations

  if (!result && _capacity_at_prologue < capacity()) {

    result = true;

    if (PrintGC && Verbose) {

      gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"

                    "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,

                    _capacity_at_prologue, capacity());

    }

  }

  return result;

}

void TenuredGeneration::collect(bool   full,

                                bool   clear_all_soft_refs,

                                size_t size,

                                bool   is_tlab) {

  retire_alloc_buffers_before_full_gc();

  OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,

                                        size, is_tlab);

}

void TenuredGeneration::update_gc_stats(int current_level,

                                        bool full) {

  // If the next lower level(s) has been collected, gather any statistics

  // that are of interest at this point.

  if (!full && (current_level + 1) == level()) {

    // Calculate size of data promoted from the younger generations

    // before doing the collection.

    size_t used_before_gc = used();

    // If the younger gen collections were skipped, then the

    // number of promoted bytes will be 0 and adding it to the

    // average will incorrectly lessen the average.  It is, however,

    // also possible that no promotion was needed.

    if (used_before_gc >= _used_at_prologue) {

      size_t promoted_in_bytes = used_before_gc - _used_at_prologue;

      gc_stats()->avg_promoted()->sample(promoted_in_bytes);

    }

  }

}

void TenuredGeneration::update_counters() {

  if (UsePerfData) {

    _space_counters->update_all();

    _gen_counters->update_all();

  }

}

#ifndef SERIALGC

oop TenuredGeneration::par_promote(int thread_num,

                                   oop old, markOop m, size_t word_sz) {

  ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];

  HeapWord* obj_ptr = buf->allocate(word_sz);

  bool is_lab = true;

  if (obj_ptr == NULL) {

#ifndef PRODUCT

    if (Universe::heap()->promotion_should_fail()) {

      return NULL;

    }

#endif  // #ifndef PRODUCT

    // Slow path:

    if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {

      // Is small enough; abandon this buffer and start a new one.

      size_t buf_size = buf->word_sz();

      HeapWord* buf_space =

        TenuredGeneration::par_allocate(buf_size, false);

      if (buf_space == NULL) {

        buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);

      }

      if (buf_space != NULL) {

        buf->retire(false, false);

        buf->set_buf(buf_space);

        obj_ptr = buf->allocate(word_sz);

        assert(obj_ptr != NULL, "Buffer was definitely big enough...");

      }

    };

    // Otherwise, buffer allocation failed; try allocating object

    // individually.

    if (obj_ptr == NULL) {

      obj_ptr = TenuredGeneration::par_allocate(word_sz, false);

      if (obj_ptr == NULL) {

        obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);

      }

    }

    if (obj_ptr == NULL) return NULL;

  }

  assert(obj_ptr != NULL, "program logic");

  Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);

  oop obj = oop(obj_ptr);

  // Restore the mark word copied above.

  obj->set_mark(m);

  return obj;

}

void TenuredGeneration::par_promote_alloc_undo(int thread_num,

                                               HeapWord* obj,

                                               size_t word_sz) {

  ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];

  if (buf->contains(obj)) {

    guarantee(buf->contains(obj + word_sz - 1),

              "should contain whole object");

    buf->undo_allocation(obj, word_sz);

  } else {

    CollectedHeap::fill_with_object(obj, word_sz);

  }

}

void TenuredGeneration::par_promote_alloc_done(int thread_num) {

  ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];

  buf->retire(true, ParallelGCRetainPLAB);

}

void TenuredGeneration::retire_alloc_buffers_before_full_gc() {

  if (UseParNewGC) {

    for (uint i = 0; i < ParallelGCThreads; i++) {

      _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);

    }

  }

}

// Verify that any retained parallel allocation buffers do not

// intersect with dirty cards.

void TenuredGeneration::verify_alloc_buffers_clean() {

  if (UseParNewGC) {

    for (uint i = 0; i < ParallelGCThreads; i++) {

      _rs->verify_aligned_region_empty(_alloc_buffers[i]->range());

    }

  }

}

#else  // SERIALGC

void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}

void TenuredGeneration::verify_alloc_buffers_clean() {}

#endif // SERIALGC

bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {

  size_t available = max_contiguous_available();

  size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();

  bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);

  if (PrintGC && Verbose) {

    gclog_or_tty->print_cr(

      "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"

      "max_promo("SIZE_FORMAT")",

      res? "":" not", available, res? ">=":"<",

      av_promo, max_promotion_in_bytes);

  }

  return res;

}