/*

 * Copyright (c) 1998, 2010, 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 "code/oopRecorder.hpp"

#include "memory/allocation.inline.hpp"

#include "oops/oop.inline.hpp"

#ifdef ASSERT

int OopRecorder::_find_index_calls = 0;

int OopRecorder::_hit_indexes      = 0;

int OopRecorder::_missed_indexes   = 0;

#endif //ASSERT

OopRecorder::OopRecorder(Arena* arena) {

  _handles  = NULL;

  _indexes  = NULL;

  _arena    = arena;

  _complete = false;

}

OopRecorder::IndexCache::IndexCache() {

  assert(first_index > 0, "initial zero state of cache must be invalid index");

  Copy::zero_to_bytes(&_cache[0], sizeof(_cache));

}

int OopRecorder::oop_size() {

  _complete = true;

  if (_handles == NULL)  return 0;

  return _handles->length() * sizeof(oop);

}

void OopRecorder::copy_to(nmethod* nm) {

  assert(_complete, "must be frozen");

  maybe_initialize();  // get non-null handles, even if we have no oops

  nm->copy_oops(_handles);

}

void OopRecorder::maybe_initialize() {

  if (_handles == NULL) {

    if (_arena != NULL) {

      _handles  = new(_arena) GrowableArray<jobject>(_arena, 10, 0, 0);

      _no_finds = new(_arena) GrowableArray<int>(    _arena, 10, 0, 0);

    } else {

      _handles  = new GrowableArray<jobject>(10, 0, 0);

      _no_finds = new GrowableArray<int>(    10, 0, 0);

    }

  }

}

jobject OopRecorder::handle_at(int index) {

  // there is always a NULL virtually present as first object

  if (index == null_index)  return NULL;

  return _handles->at(index - first_index);

}

// Local definition.  Used only in this module.

inline bool OopRecorder::is_real_jobject(jobject h) {

  return h != NULL && h != (jobject)Universe::non_oop_word();

}

int OopRecorder::add_handle(jobject h, bool make_findable) {

  assert(!_complete, "cannot allocate more elements after size query");

  maybe_initialize();

  // indexing uses 1 as an origin--0 means null

  int index = _handles->length() + first_index;

  _handles->append(h);

  // Support correct operation of find_index().

  assert(!(make_findable && !is_real_jobject(h)), "nulls are not findable");

  if (make_findable) {

    // This index may be returned from find_index().

    if (_indexes != NULL) {

      int* cloc = _indexes->cache_location(h);

      _indexes->set_cache_location_index(cloc, index);

    } else if (index == index_cache_threshold && _arena != NULL) {

      _indexes = new(_arena) IndexCache();

      for (int i = 0; i < _handles->length(); i++) {

        // Load the cache with pre-existing elements.

        int index0 = i + first_index;

        if (_no_finds->contains(index0))  continue;

        int* cloc = _indexes->cache_location(_handles->at(i));

        _indexes->set_cache_location_index(cloc, index0);

      }

    }

  } else if (is_real_jobject(h)) {

    // Remember that this index is not to be returned from find_index().

    // This case is rare, because most or all uses of allocate_index pass

    // a jobject argument of NULL or Universe::non_oop_word.

    // Thus, the expected length of _no_finds is zero.

    _no_finds->append(index);

  }

  return index;

}

int OopRecorder::maybe_find_index(jobject h) {

  debug_only(_find_index_calls++);

  assert(!_complete, "cannot allocate more elements after size query");

  maybe_initialize();

  if (h == NULL)  return null_index;

  assert(is_real_jobject(h), "must be valid jobject");

  int* cloc = (_indexes == NULL)? NULL: _indexes->cache_location(h);

  if (cloc != NULL) {

    int cindex = _indexes->cache_location_index(cloc);

    if (cindex == 0) {

      return -1;   // We know this handle is completely new.

    }

    if (cindex >= first_index && _handles->at(cindex - first_index) == h) {

      debug_only(_hit_indexes++);

      return cindex;

    }

    if (!_indexes->cache_location_collision(cloc)) {

      return -1;   // We know the current cache occupant is unique to that cloc.

    }

  }

  // Not found in cache, due to a cache collision.  (Or, no cache at all.)

  // Do a linear search, most recent to oldest.

  for (int i = _handles->length() - 1; i >= 0; i--) {

    if (_handles->at(i) == h) {

      int findex = i + first_index;

      if (_no_finds->contains(findex))  continue;  // oops; skip this one

      if (cloc != NULL) {

        _indexes->set_cache_location_index(cloc, findex);

      }

      debug_only(_missed_indexes++);

      return findex;

    }

  }

  return -1;

}