/*

 * Copyright (c) 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/z/zThreadLocalData.hpp"

#include "gc/z/zObjArrayAllocator.hpp"

#include "gc/z/zUtils.inline.hpp"

#include "oops/arrayKlass.hpp"

#include "runtime/interfaceSupport.inline.hpp"

ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :

    ObjArrayAllocator(klass, word_size, length, false /* do_zero */, thread) {}

oop ZObjArrayAllocator::finish(HeapWord* mem) const {

  // Initialize object header and length field

  ObjArrayAllocator::finish(mem);

  // Keep the array alive across safepoints through an invisible

  // root. Invisible roots are not visited by the heap itarator

  // and the marking logic will not attempt to follow its elements.

  ZThreadLocalData::set_invisible_root(_thread, (oop*)&mem);

  // A max segment size of 64K was chosen because microbenchmarking

  // suggested that it offered a good trade-off between allocation

  // time and time-to-safepoint

  const size_t segment_max = ZUtils::bytes_to_words(64 * K);

  const size_t skip = arrayOopDesc::header_size(ArrayKlass::cast(_klass)->element_type());

  size_t remaining = _word_size - skip;

  while (remaining > 0) {

    // Clear segment

    const size_t segment = MIN2(remaining, segment_max);

    Copy::zero_to_words(mem + (_word_size - remaining), segment);

    remaining -= segment;

    if (remaining > 0) {

      // Safepoint

      ThreadBlockInVM tbivm((JavaThread*)_thread);

    }

  }

  ZThreadLocalData::clear_invisible_root(_thread);

  return oop(mem);

}