/*

 * Copyright (c) 2017, 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/zNMethodTableEntry.hpp"

#include "gc/z/zNMethodTableIteration.hpp"

#include "memory/iterator.hpp"

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

ZNMethodTableIteration::ZNMethodTableIteration() :

    _table(NULL),

    _size(0),

    _claimed(0) {}

bool ZNMethodTableIteration::in_progress() const {

  return _table != NULL;

}

void ZNMethodTableIteration::nmethods_do_begin(ZNMethodTableEntry* table, size_t size) {

  assert(!in_progress(), "precondition");

  _table = table;

  _size = size;

  _claimed = 0;

}

void ZNMethodTableIteration::nmethods_do_end() {

  assert(_claimed >= _size, "Failed to claim all table entries");

  // Finish iteration

  _table = NULL;

}

void ZNMethodTableIteration::nmethods_do(NMethodClosure* cl) {

  for (;;) {

    // Claim table partition. Each partition is currently sized to span

    // two cache lines. This number is just a guess, but seems to work well.

    const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);

    const size_t partition_start = MIN2(Atomic::add(&_claimed, partition_size) - partition_size, _size);

    const size_t partition_end = MIN2(partition_start + partition_size, _size);

    if (partition_start == partition_end) {

      // End of table

      break;

    }

    // Process table partition

    for (size_t i = partition_start; i < partition_end; i++) {

      const ZNMethodTableEntry entry = _table[i];

      if (entry.registered()) {

        cl->do_nmethod(entry.method());

      }

    }

  }

}