src/hotspot/share/gc/shared/preservedMarks.cpp

/*
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 * 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/shared/preservedMarks.inline.hpp"
#include "gc/shared/workerThread.hpp"
#include "gc/shared/workerUtils.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
#include "utilities/macros.hpp"

void PreservedMarks::restore() {
  while (!_stack.is_empty()) {
    const OopAndMarkWord elem = _stack.pop();
    elem.set_mark();
  }
  assert_empty();
}

void PreservedMarks::adjust_during_full_gc() {
  StackIterator<OopAndMarkWord, mtGC> iter(_stack);
  while (!iter.is_empty()) {
    OopAndMarkWord* elem = iter.next_addr();

    oop obj = elem->get_oop();
    if (obj->is_forwarded()) {
      elem->set_oop(obj->forwardee());
    }
  }
}

void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {
  const size_t stack_size = size();
  restore();
  // Only do the atomic add if the size is > 0.
  if (stack_size > 0) {
    Atomic::add(total_size_addr, stack_size);
  }
}

#ifndef PRODUCT
void PreservedMarks::assert_empty() {
  assert(_stack.is_empty(), "stack expected to be empty, size = " SIZE_FORMAT,
         _stack.size());
  assert(_stack.cache_size() == 0,
         "stack expected to have no cached segments, cache size = " SIZE_FORMAT,
         _stack.cache_size());
}
#endif // ndef PRODUCT

void PreservedMarksSet::init(uint num) {
  assert(_stacks == nullptr && _num == 0, "do not re-initialize");
  assert(num > 0, "pre-condition");
  if (_in_c_heap) {
    _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);
  } else {
    _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);
  }
  for (uint i = 0; i < num; i += 1) {
    ::new (_stacks + i) PreservedMarks();
  }
  _num = num;

  assert_empty();
}

class RestorePreservedMarksTask : public WorkerTask {
  PreservedMarksSet* const _preserved_marks_set;
  SequentialSubTasksDone _sub_tasks;
  volatile size_t _total_size;
#ifdef ASSERT
  size_t _total_size_before;
#endif // ASSERT

public:
  void work(uint worker_id) override {
    uint task_id = 0;
    while (_sub_tasks.try_claim_task(task_id)) {
      _preserved_marks_set->get(task_id)->restore_and_increment(&_total_size);
    }
  }

  RestorePreservedMarksTask(PreservedMarksSet* preserved_marks_set)
    : WorkerTask("Restore Preserved Marks"),
      _preserved_marks_set(preserved_marks_set),
      _sub_tasks(preserved_marks_set->num()),
      _total_size(0)
      DEBUG_ONLY(COMMA _total_size_before(0)) {
#ifdef ASSERT
    // This is to make sure the total_size we'll calculate below is correct.
    for (uint i = 0; i < _preserved_marks_set->num(); ++i) {
      _total_size_before += _preserved_marks_set->get(i)->size();
    }
#endif // ASSERT
  }

  ~RestorePreservedMarksTask() {
    assert(_total_size == _total_size_before, "total_size = %zu before = %zu", _total_size, _total_size_before);
    size_t mem_size = _total_size * (sizeof(oop) + sizeof(markWord));
    log_trace(gc)("Restored %zu marks, occupying %zu %s", _total_size,
                                                          byte_size_in_proper_unit(mem_size),
                                                          proper_unit_for_byte_size(mem_size));
  }
};

void PreservedMarksSet::restore(WorkerThreads* workers) {
  {
    RestorePreservedMarksTask cl(this);
    if (workers == nullptr) {
      cl.work(0);
    } else {
      workers->run_task(&cl);
    }
  }

  assert_empty();
}

WorkerTask* PreservedMarksSet::create_task() {
  return new RestorePreservedMarksTask(this);
}

void PreservedMarksSet::reclaim() {
  assert_empty();

  for (uint i = 0; i < _num; i += 1) {
    _stacks[i].~Padded<PreservedMarks>();
  }

  if (_in_c_heap) {
    FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);
  } else {
    // the array was resource-allocated, so nothing to do
  }
  _stacks = nullptr;
  _num = 0;
}

#ifndef PRODUCT
void PreservedMarksSet::assert_empty() {
  assert(_stacks != nullptr && _num > 0, "should have been initialized");
  for (uint i = 0; i < _num; i += 1) {
    get(i)->assert_empty();
  }
}
#endif // ndef PRODUCT