/*

 * Copyright (c) 2001, 2013, 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_implementation/shared/collectorCounters.hpp"

#include "gc_implementation/shared/gcTimer.hpp"

#include "gc_implementation/shared/parGCAllocBuffer.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/blockOffsetTable.inline.hpp"

#include "memory/generationSpec.hpp"

#include "memory/genMarkSweep.hpp"

#include "memory/genOopClosures.inline.hpp"

#include "memory/space.hpp"

#include "memory/tenuredGeneration.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

#include "utilities/macros.hpp"

TenuredGeneration::TenuredGeneration(ReservedSpace rs,

                                     size_t initial_byte_size, int level,

                                     GenRemSet* remset) :

  CardGeneration(rs, initial_byte_size, level, 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";

  GenCollectorPolicy* gcp = (GenCollectorPolicy*) GenCollectedHeap::heap()->collector_policy();

  // Generation Counters -- generation 1, 1 subspace

  _gen_counters = new GenerationCounters(gen_name, 1, 1,

      gcp->min_old_size(), gcp->max_old_size(), &_virtual_space);

  _gc_counters = new CollectorCounters("MSC", 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.

  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 accommodate 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::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(),

         err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT

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

}

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();

  }

}

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;

}

void TenuredGeneration::collect(bool   full,

                                bool   clear_all_soft_refs,

                                size_t size,

                                bool   is_tlab) {

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  SpecializationStats::clear();

  // 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());

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

  gc_timer->register_gc_end();

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

  SpecializationStats::print();

}

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::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);

      }

      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);

}

void TenuredGeneration::shrink(size_t bytes) {

  assert_locked_or_safepoint(ExpandHeap_lock);

  size_t size = ReservedSpace::page_align_size_down(bytes);

  if (size > 0) {

    shrink_by(size);

  }

}

size_t TenuredGeneration::capacity() const {

  return _the_space->capacity();

}

size_t TenuredGeneration::used() const {

  return _the_space->used();

}

size_t TenuredGeneration::free() const {

  return _the_space->free();

}

MemRegion TenuredGeneration::used_region() const {

  return the_space()->used_region();

}

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();

}

bool TenuredGeneration::grow_by(size_t bytes) {

  assert_locked_or_safepoint(ExpandHeap_lock);

  bool result = _virtual_space.expand_by(bytes);

  if (result) {

    size_t new_word_size =

       heap_word_size(_virtual_space.committed_size());

    MemRegion mr(_the_space->bottom(), new_word_size);

    // Expand card table

    Universe::heap()->barrier_set()->resize_covered_region(mr);

    // Expand shared block offset array

    _bts->resize(new_word_size);

    // Fix for bug #4668531

    if (ZapUnusedHeapArea) {

      MemRegion mangle_region(_the_space->end(),

      (HeapWord*)_virtual_space.high());

      SpaceMangler::mangle_region(mangle_region);

    }

    // Expand space -- also expands space's BOT

    // (which uses (part of) shared array above)

    _the_space->set_end((HeapWord*)_virtual_space.high());

    // update the space and generation capacity counters

    update_counters();

    if (Verbose && PrintGC) {

      size_t new_mem_size = _virtual_space.committed_size();

      size_t old_mem_size = new_mem_size - bytes;

      gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "

                      SIZE_FORMAT "K to " SIZE_FORMAT "K",

                      name(), old_mem_size/K, bytes/K, new_mem_size/K);

    }

  }

  return result;

}

bool TenuredGeneration::grow_to_reserved() {

  assert_locked_or_safepoint(ExpandHeap_lock);

  bool success = true;

  const size_t remaining_bytes = _virtual_space.uncommitted_size();

  if (remaining_bytes > 0) {

    success = grow_by(remaining_bytes);

    DEBUG_ONLY(if (!success) warning("grow to reserved failed");)

  }

  return success;

}

void TenuredGeneration::shrink_by(size_t bytes) {

  assert_locked_or_safepoint(ExpandHeap_lock);

  // Shrink committed space

  _virtual_space.shrink_by(bytes);

  // Shrink space; this also shrinks the space's BOT

  _the_space->set_end((HeapWord*) _virtual_space.high());

  size_t new_word_size = heap_word_size(_the_space->capacity());

  // Shrink the shared block offset array

  _bts->resize(new_word_size);

  MemRegion mr(_the_space->bottom(), new_word_size);

  // Shrink the card table

  Universe::heap()->barrier_set()->resize_covered_region(mr);

  if (Verbose && PrintGC) {

    size_t new_mem_size = _virtual_space.committed_size();

    size_t old_mem_size = new_mem_size + bytes;

    gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",

                  name(), old_mem_size/K, new_mem_size/K);

  }

}

// Currently nothing to do.

void TenuredGeneration::prepare_for_verify() {}

void TenuredGeneration::object_iterate(ObjectClosure* blk) {

  _the_space->object_iterate(blk);

}

void TenuredGeneration::space_iterate(SpaceClosure* blk,

                                                 bool usedOnly) {

  blk->do_space(_the_space);

}

void TenuredGeneration::younger_refs_iterate(OopsInGenClosure* blk) {

  blk->set_generation(this);

  younger_refs_in_space_iterate(_the_space, blk);

  blk->reset_generation();

}

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();

}

#define TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)     \

                                                                                \

void TenuredGeneration::                                                        \

oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {                  \

  blk->set_generation(this);                                                    \

  _the_space->oop_since_save_marks_iterate##nv_suffix(blk);                     \

  blk->reset_generation();                                                      \

  save_marks();                                                                 \

}

ALL_SINCE_SAVE_MARKS_CLOSURES(TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN)

#undef TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN

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);

}