/*

 * Copyright (c) 2001, 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/serial/genMarkSweep.hpp"

#include "gc/serial/tenuredGeneration.inline.hpp"

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

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

#include "gc/shared/collectorCounters.hpp"

#include "gc/shared/gcTimer.hpp"

#include "gc/shared/gcTrace.hpp"

#include "gc/shared/genCollectedHeap.hpp"

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

#include "gc/shared/generationSpec.hpp"

#include "gc/shared/space.hpp"

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

#include "utilities/macros.hpp"

TenuredGeneration::TenuredGeneration(ReservedSpace rs,

                                     size_t initial_byte_size,

                                     size_t min_byte_size,

                                     size_t max_byte_size,

                                     CardTableRS* remset) :

  CardGeneration(rs, initial_byte_size, remset)

{

  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,

      min_byte_size, max_byte_size, &_virtual_space);

  _gc_counters = new CollectorCounters("Serial full collection pauses", 1);

  _space_counters = new CSpaceCounters(gen_name, 0,

                                       _virtual_space.reserved_size(),

                                       _the_space, _gen_counters);

}

void TenuredGeneration::gc_prologue(bool full) {

  _capacity_at_prologue = capacity();

  _used_at_prologue = used();

}

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.

  if (full) {

    log_trace(gc)("TenuredGeneration::should_collect: because full");

    return true;

  }

  if (should_allocate(size, is_tlab)) {

    log_trace(gc)("TenuredGeneration::should_collect: because should_allocate(" SIZE_FORMAT ")", size);

    return true;

  }

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

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

  if (free() < 10000) {

    log_trace(gc)("TenuredGeneration::should_collect: because free(): " SIZE_FORMAT, free());

    return true;

  }

  // If we had to expand to accommodate promotions from the young generation

  if (_capacity_at_prologue < capacity()) {

    log_trace(gc)("TenuredGeneration::should_collect: because_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,

        _capacity_at_prologue, capacity());

    return true;

  }

  return false;

}

void TenuredGeneration::compute_new_size() {

  assert_locked_or_safepoint(Heap_lock);

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

  const size_t used_after_gc = used();

  const size_t capacity_after_gc = capacity();

  CardGeneration::compute_new_size();

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

         "used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT

         " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity());

}

void TenuredGeneration::update_gc_stats(Generation* current_generation,

                                        bool full) {

  // If the young generation has been collected, gather any statistics

  // that are of interest at this point.

  bool current_is_young = GenCollectedHeap::heap()->is_young_gen(current_generation);

  if (!full && current_is_young) {

    // Calculate size of data promoted from the young generation

    // before doing the collection.

    size_t used_before_gc = used();

    // If the young gen collection was 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();

  }

}

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);

  log_trace(gc)("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;

}

void TenuredGeneration::collect(bool   full,

                                bool   clear_all_soft_refs,

                                size_t size,

                                bool   is_tlab) {

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  // Temporarily expand the span of our ref processor, so

  // refs discovery is over the entire heap, not just this generation

  ReferenceProcessorSpanMutator

    x(ref_processor(), gch->reserved_region());

  STWGCTimer* gc_timer = GenMarkSweep::gc_timer();

  gc_timer->register_gc_start();

  SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();

  gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());

  gch->pre_full_gc_dump(gc_timer);

  GenMarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);

  gch->post_full_gc_dump(gc_timer);

  gc_timer->register_gc_end();

  gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());

}

HeapWord*

TenuredGeneration::expand_and_allocate(size_t word_size,

                                       bool is_tlab,

                                       bool parallel) {

  assert(!is_tlab, "TenuredGeneration does not support TLAB allocation");

  if (parallel) {

    MutexLocker x(ParGCRareEvent_lock);

    HeapWord* result = NULL;

    size_t byte_size = word_size * HeapWordSize;

    while (true) {

      expand(byte_size, _min_heap_delta_bytes);

      if (GCExpandToAllocateDelayMillis > 0) {

        os::naked_sleep(GCExpandToAllocateDelayMillis);

      }

      result = _the_space->par_allocate(word_size);

      if ( result != NULL) {

        return result;

      } else {

        // If there's not enough expansion space available, give up.

        if (_virtual_space.uncommitted_size() < byte_size) {

          return NULL;

        }

        // else try again

      }

    }

  } else {

    expand(word_size*HeapWordSize, _min_heap_delta_bytes);

    return _the_space->allocate(word_size);

  }

}

bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) {

  GCMutexLocker x(ExpandHeap_lock);

  return CardGeneration::expand(bytes, expand_bytes);

}

size_t TenuredGeneration::unsafe_max_alloc_nogc() const {

  return _the_space->free();

}

size_t TenuredGeneration::contiguous_available() const {

  return _the_space->free() + _virtual_space.uncommitted_size();

}

void TenuredGeneration::assert_correct_size_change_locking() {

  assert_locked_or_safepoint(ExpandHeap_lock);

}

// Currently nothing to do.

void TenuredGeneration::prepare_for_verify() {}

void TenuredGeneration::object_iterate(ObjectClosure* blk) {

  _the_space->object_iterate(blk);

}

void TenuredGeneration::save_marks() {

  _the_space->set_saved_mark();

}

void TenuredGeneration::reset_saved_marks() {

  _the_space->reset_saved_mark();

}

bool TenuredGeneration::no_allocs_since_save_marks() {

  return _the_space->saved_mark_at_top();

}

void TenuredGeneration::gc_epilogue(bool full) {

  // update the generation and space performance counters

  update_counters();

  if (ZapUnusedHeapArea) {

    _the_space->check_mangled_unused_area_complete();

  }

}

void TenuredGeneration::record_spaces_top() {

  assert(ZapUnusedHeapArea, "Not mangling unused space");

  _the_space->set_top_for_allocations();

}

void TenuredGeneration::verify() {

  _the_space->verify();

}

void TenuredGeneration::print_on(outputStream* st)  const {

  Generation::print_on(st);

  st->print("   the");

  _the_space->print_on(st);

}