/*

 * Copyright (c) 2015, 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.

 */

#ifndef SHARE_GC_Z_ZFORWARDING_INLINE_HPP

#define SHARE_GC_Z_ZFORWARDING_INLINE_HPP

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

#include "gc/z/zForwarding.hpp"

#include "gc/z/zGlobals.hpp"

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

#include "gc/z/zHeap.hpp"

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

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

inline uintptr_t ZForwarding::start() const {

  return _virtual.start();

}

inline size_t ZForwarding::size() const {

  return _virtual.size();

}

inline size_t ZForwarding::object_alignment_shift() const {

  return _object_alignment_shift;

}

inline ZPage* ZForwarding::page() const {

  return _page;

}

inline bool ZForwarding::is_pinned() const {

  return Atomic::load(&_pinned);

}

inline void ZForwarding::set_pinned() {

  Atomic::store(true, &_pinned);

}

inline bool ZForwarding::inc_refcount() {

  uint32_t refcount = Atomic::load(&_refcount);

  while (refcount > 0) {

    const uint32_t old_refcount = refcount;

    const uint32_t new_refcount = old_refcount + 1;

    const uint32_t prev_refcount = Atomic::cmpxchg(new_refcount, &_refcount, old_refcount);

    if (prev_refcount == old_refcount) {

      return true;

    }

    refcount = prev_refcount;

  }

  return false;

}

inline bool ZForwarding::dec_refcount() {

  assert(_refcount > 0, "Invalid state");

  return Atomic::sub(1u, &_refcount) == 0u;

}

inline bool ZForwarding::retain_page() {

  return inc_refcount();

}

inline void ZForwarding::release_page() {

  if (dec_refcount()) {

    ZHeap::heap()->free_page(_page, true /* reclaimed */);

    _page = NULL;

  }

}

inline ZForwardingEntry* ZForwarding::entries() const {

  return _entries(this);

}

inline ZForwardingEntry ZForwarding::at(ZForwardingCursor* cursor) const {

  return Atomic::load(entries() + *cursor);

}

inline ZForwardingEntry ZForwarding::first(uintptr_t from_index, ZForwardingCursor* cursor) const {

  const size_t mask = _entries.length() - 1;

  const size_t hash = ZHash::uint32_to_uint32((uint32_t)from_index);

  *cursor = hash & mask;

  return at(cursor);

}

inline ZForwardingEntry ZForwarding::next(ZForwardingCursor* cursor) const {

  const size_t mask = _entries.length() - 1;

  *cursor = (*cursor + 1) & mask;

  return at(cursor);

}

inline ZForwardingEntry ZForwarding::find(uintptr_t from_index) const {

  ZForwardingCursor dummy;

  return find(from_index, &dummy);

}

inline ZForwardingEntry ZForwarding::find(uintptr_t from_index, ZForwardingCursor* cursor) const {

  // Reading entries in the table races with the atomic CAS done for

  // insertion into the table. This is safe because each entry is at

  // most updated once (from zero to something else).

  ZForwardingEntry entry = first(from_index, cursor);

  while (entry.populated()) {

    if (entry.from_index() == from_index) {

      // Match found, return matching entry

      return entry;

    }

    entry = next(cursor);

  }

  // Match not found, return empty entry

  return entry;

}

inline uintptr_t ZForwarding::insert(uintptr_t from_index, uintptr_t to_offset, ZForwardingCursor* cursor) {

  const ZForwardingEntry new_entry(from_index, to_offset);

  const ZForwardingEntry old_entry; // Empty

  for (;;) {

    const ZForwardingEntry prev_entry = Atomic::cmpxchg(new_entry, entries() + *cursor, old_entry);

    if (!prev_entry.populated()) {

      // Success

      return to_offset;

    }

    // Find next empty or matching entry

    ZForwardingEntry entry = at(cursor);

    while (entry.populated()) {

      if (entry.from_index() == from_index) {

        // Match found, return already inserted address

        return entry.to_offset();

      }

      entry = next(cursor);

    }

  }

}

#endif // SHARE_GC_Z_ZFORWARDING_INLINE_HPP