/*

 * Copyright (c) 1997, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

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 */

#include "precompiled.hpp"

#include "gc_implementation/shared/gcTimer.hpp"

#include "gc_implementation/shared/gcTrace.hpp"

#include "gc_implementation/shared/spaceDecorator.hpp"

#include "gc_interface/collectedHeap.inline.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/blockOffsetTable.inline.hpp"

#include "memory/cardTableRS.hpp"

#include "memory/gcLocker.inline.hpp"

#include "memory/genCollectedHeap.hpp"

#include "memory/genMarkSweep.hpp"

#include "memory/genOopClosures.hpp"

#include "memory/genOopClosures.inline.hpp"

#include "memory/generation.hpp"

#include "memory/generation.inline.hpp"

#include "memory/space.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

#include "utilities/copy.hpp"

#include "utilities/events.hpp"

Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :

  _level(level),

  _ref_processor(NULL) {

  if (!_virtual_space.initialize(rs, initial_size)) {

    vm_exit_during_initialization("Could not reserve enough space for "

                    "object heap");

  }

  // Mangle all of the the initial generation.

  if (ZapUnusedHeapArea) {

    MemRegion mangle_region((HeapWord*)_virtual_space.low(),

      (HeapWord*)_virtual_space.high());

    SpaceMangler::mangle_region(mangle_region);

  }

  _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),

          (HeapWord*)_virtual_space.high_boundary());

}

GenerationSpec* Generation::spec() {

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  assert(0 <= level() && level() < gch->_n_gens, "Bad gen level");

  return gch->_gen_specs[level()];

}

size_t Generation::max_capacity() const {

  return reserved().byte_size();

}

void Generation::print_heap_change(size_t prev_used) const {

  if (PrintGCDetails && Verbose) {

    gclog_or_tty->print(" "  SIZE_FORMAT

                        "->" SIZE_FORMAT

                        "("  SIZE_FORMAT ")",

                        prev_used, used(), capacity());

  } else {

    gclog_or_tty->print(" "  SIZE_FORMAT "K"

                        "->" SIZE_FORMAT "K"

                        "("  SIZE_FORMAT "K)",

                        prev_used / K, used() / K, capacity() / K);

  }

}

// By default we get a single threaded default reference processor;

// generations needing multi-threaded refs processing or discovery override this method.

void Generation::ref_processor_init() {

  assert(_ref_processor == NULL, "a reference processor already exists");

  assert(!_reserved.is_empty(), "empty generation?");

  _ref_processor = new ReferenceProcessor(_reserved);    // a vanilla reference processor

  if (_ref_processor == NULL) {

    vm_exit_during_initialization("Could not allocate ReferenceProcessor object");

  }

}

void Generation::print() const { print_on(tty); }

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

  st->print(" %-20s", name());

  st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",

             capacity()/K, used()/K);

  st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",

              _virtual_space.low_boundary(),

              _virtual_space.high(),

              _virtual_space.high_boundary());

}

void Generation::print_summary_info() { print_summary_info_on(tty); }

void Generation::print_summary_info_on(outputStream* st) {

  StatRecord* sr = stat_record();

  double time = sr->accumulated_time.seconds();

  st->print_cr("[Accumulated GC generation %d time %3.7f secs, "

               "%d GC's, avg GC time %3.7f]",

               level(), time, sr->invocations,

               sr->invocations > 0 ? time / sr->invocations : 0.0);

}

// Utility iterator classes

class GenerationIsInReservedClosure : public SpaceClosure {

 public:

  const void* _p;

  Space* sp;

  virtual void do_space(Space* s) {

    if (sp == NULL) {

      if (s->is_in_reserved(_p)) sp = s;

    }

  }

  GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}

};

class GenerationIsInClosure : public SpaceClosure {

 public:

  const void* _p;

  Space* sp;

  virtual void do_space(Space* s) {

    if (sp == NULL) {

      if (s->is_in(_p)) sp = s;

    }

  }

  GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}

};

bool Generation::is_in(const void* p) const {

  GenerationIsInClosure blk(p);

  ((Generation*)this)->space_iterate(&blk);

  return blk.sp != NULL;

}

DefNewGeneration* Generation::as_DefNewGeneration() {

  assert((kind() == Generation::DefNew) ||

         (kind() == Generation::ParNew) ||

         (kind() == Generation::ASParNew),

    "Wrong youngest generation type");

  return (DefNewGeneration*) this;

}

Generation* Generation::next_gen() const {

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  int next = level() + 1;

  if (next < gch->_n_gens) {

    return gch->_gens[next];

  } else {

    return NULL;

  }

}

size_t Generation::max_contiguous_available() const {

  // The largest number of contiguous free words in this or any higher generation.

  size_t max = 0;

  for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) {

    size_t avail = gen->contiguous_available();

    if (avail > max) {

      max = avail;

    }

  }

  return max;

}

bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {

  size_t available = max_contiguous_available();

  bool   res = (available >= max_promotion_in_bytes);

  if (PrintGC && Verbose) {

    gclog_or_tty->print_cr(

      "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")",

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

      max_promotion_in_bytes);

  }

  return res;

}

// Ignores "ref" and calls allocate().

oop Generation::promote(oop obj, size_t obj_size) {

  assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");

#ifndef PRODUCT

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

    return NULL;

  }

#endif  // #ifndef PRODUCT

  HeapWord* result = allocate(obj_size, false);

  if (result != NULL) {

    Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);

    return oop(result);

  } else {

    GenCollectedHeap* gch = GenCollectedHeap::heap();

    return gch->handle_failed_promotion(this, obj, obj_size);

  }

}

oop Generation::par_promote(int thread_num,

                            oop obj, markOop m, size_t word_sz) {

  // Could do a bad general impl here that gets a lock.  But no.

  ShouldNotCallThis();

  return NULL;

}

void Generation::par_promote_alloc_undo(int thread_num,

                                        HeapWord* obj, size_t word_sz) {

  // Could do a bad general impl here that gets a lock.  But no.

  guarantee(false, "No good general implementation.");

}

Space* Generation::space_containing(const void* p) const {

  GenerationIsInReservedClosure blk(p);

  // Cast away const

  ((Generation*)this)->space_iterate(&blk);

  return blk.sp;

}

// Some of these are mediocre general implementations.  Should be

// overridden to get better performance.

class GenerationBlockStartClosure : public SpaceClosure {

 public:

  const void* _p;

  HeapWord* _start;

  virtual void do_space(Space* s) {

    if (_start == NULL && s->is_in_reserved(_p)) {

      _start = s->block_start(_p);

    }

  }

  GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }

};

HeapWord* Generation::block_start(const void* p) const {

  GenerationBlockStartClosure blk(p);

  // Cast away const

  ((Generation*)this)->space_iterate(&blk);

  return blk._start;

}

class GenerationBlockSizeClosure : public SpaceClosure {

 public:

  const HeapWord* _p;

  size_t size;

  virtual void do_space(Space* s) {

    if (size == 0 && s->is_in_reserved(_p)) {

      size = s->block_size(_p);

    }

  }

  GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }

};

size_t Generation::block_size(const HeapWord* p) const {

  GenerationBlockSizeClosure blk(p);

  // Cast away const

  ((Generation*)this)->space_iterate(&blk);

  assert(blk.size > 0, "seems reasonable");

  return blk.size;

}

class GenerationBlockIsObjClosure : public SpaceClosure {

 public:

  const HeapWord* _p;

  bool is_obj;

  virtual void do_space(Space* s) {

    if (!is_obj && s->is_in_reserved(_p)) {

      is_obj |= s->block_is_obj(_p);

    }

  }

  GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }

};

bool Generation::block_is_obj(const HeapWord* p) const {

  GenerationBlockIsObjClosure blk(p);

  // Cast away const

  ((Generation*)this)->space_iterate(&blk);

  return blk.is_obj;

}

class GenerationOopIterateClosure : public SpaceClosure {

 public:

  virtual void do_space(Space* s) {

  }

};

void Generation::oop_iterate(ExtendedOopClosure* cl) {

  space_iterate(&blk);

}

void Generation::younger_refs_in_space_iterate(Space* sp,

                                               OopsInGenClosure* cl) {

  GenRemSet* rs = SharedHeap::heap()->rem_set();

  rs->younger_refs_in_space_iterate(sp, cl);

}

class GenerationObjIterateClosure : public SpaceClosure {

 private:

  ObjectClosure* _cl;

 public:

  virtual void do_space(Space* s) {

    s->object_iterate(_cl);

  }

  GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}

};

void Generation::object_iterate(ObjectClosure* cl) {

  GenerationObjIterateClosure blk(cl);

  space_iterate(&blk);

}

class GenerationSafeObjIterateClosure : public SpaceClosure {

 private:

  ObjectClosure* _cl;

 public:

  virtual void do_space(Space* s) {

    s->safe_object_iterate(_cl);

  }

  GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}

};

void Generation::safe_object_iterate(ObjectClosure* cl) {

  GenerationSafeObjIterateClosure blk(cl);

  space_iterate(&blk);

}

void Generation::prepare_for_compaction(CompactPoint* cp) {

  // Generic implementation, can be specialized

  CompactibleSpace* space = first_compaction_space();

  while (space != NULL) {

    space->prepare_for_compaction(cp);

    space = space->next_compaction_space();

  }

}

class AdjustPointersClosure: public SpaceClosure {

 public:

  void do_space(Space* sp) {

    sp->adjust_pointers();

  }

};

void Generation::adjust_pointers() {

  // Note that this is done over all spaces, not just the compactible

  // ones.

  AdjustPointersClosure blk;

  space_iterate(&blk, true);

}

void Generation::compact() {

  CompactibleSpace* sp = first_compaction_space();

  while (sp != NULL) {

    sp->compact();

    sp = sp->next_compaction_space();

  }

}

CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,

                               int level,

                               GenRemSet* remset) :

  Generation(rs, initial_byte_size, level), _rs(remset),

  _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(),

  _used_at_prologue()

{

  HeapWord* start = (HeapWord*)rs.base();

  size_t reserved_byte_size = rs.size();

  assert((uintptr_t(start) & 3) == 0, "bad alignment");

  assert((reserved_byte_size & 3) == 0, "bad alignment");

  MemRegion reserved_mr(start, heap_word_size(reserved_byte_size));

  _bts = new BlockOffsetSharedArray(reserved_mr,

                                    heap_word_size(initial_byte_size));

  MemRegion committed_mr(start, heap_word_size(initial_byte_size));

  _rs->resize_covered_region(committed_mr);

  if (_bts == NULL)

    vm_exit_during_initialization("Could not allocate a BlockOffsetArray");

  // Verify that the start and end of this generation is the start of a card.

  // If this wasn't true, a single card could span more than on generation,

  // which would cause problems when we commit/uncommit memory, and when we

  // clear and dirty cards.

  guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned");

  if (reserved_mr.end() != Universe::heap()->reserved_region().end()) {

    // Don't check at the very end of the heap as we'll assert that we're probing off

    // the end if we try.

    guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned");

  }

  _min_heap_delta_bytes = MinHeapDeltaBytes;

  _capacity_at_prologue = initial_byte_size;

  _used_at_prologue = 0;

}

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

  assert_locked_or_safepoint(Heap_lock);

  if (bytes == 0) {

    return true;  // That's what grow_by(0) would return

  }

  size_t aligned_bytes  = ReservedSpace::page_align_size_up(bytes);

  if (aligned_bytes == 0){

    // The alignment caused the number of bytes to wrap.  An expand_by(0) will

    // return true with the implication that an expansion was done when it

    // was not.  A call to expand implies a best effort to expand by "bytes"

    // but not a guarantee.  Align down to give a best effort.  This is likely

    // the most that the generation can expand since it has some capacity to

    // start with.

    aligned_bytes = ReservedSpace::page_align_size_down(bytes);

  }

  size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);

  bool success = false;

  if (aligned_expand_bytes > aligned_bytes) {

    success = grow_by(aligned_expand_bytes);

  }

  if (!success) {

    success = grow_by(aligned_bytes);

  }

  if (!success) {

    success = grow_to_reserved();

  }

  if (PrintGC && Verbose) {

    if (success && GC_locker::is_active_and_needs_gc()) {

      gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");

    }

  }

  return success;

}

// No young generation references, clear this generation's cards.

void CardGeneration::clear_remembered_set() {

  _rs->clear(reserved());

}

// Objects in this generation may have moved, invalidate this

// generation's cards.

void CardGeneration::invalidate_remembered_set() {

  _rs->invalidate(used_region());

}

void CardGeneration::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,