/*

 * Copyright (c) 2014, 2018, 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 "jfr/leakprofiler/chains/dfsClosure.hpp"

#include "jfr/leakprofiler/chains/edge.hpp"

#include "jfr/leakprofiler/chains/edgeStore.hpp"

#include "jfr/leakprofiler/utilities/granularTimer.hpp"

#include "jfr/leakprofiler/chains/bitset.hpp"

#include "jfr/leakprofiler/utilities/unifiedOop.hpp"

#include "jfr/leakprofiler/utilities/rootType.hpp"

#include "jfr/leakprofiler/chains/rootSetClosure.hpp"

#include "memory/resourceArea.hpp"

#include "oops/access.inline.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/align.hpp"

// max dfs depth should not exceed size of stack

static const size_t max_dfs_depth = 5000;

EdgeStore* DFSClosure::_edge_store = NULL;

BitSet* DFSClosure::_mark_bits = NULL;

const Edge* DFSClosure::_start_edge = NULL;

size_t DFSClosure::_max_depth = max_dfs_depth;

bool DFSClosure::_ignore_root_set = false;

DFSClosure::DFSClosure() :

  _parent(NULL),

  _reference(NULL),

  _depth(0) {

}

DFSClosure::DFSClosure(DFSClosure* parent, size_t depth) :

  _parent(parent),

  _reference(NULL),

  _depth(depth) {

}

void DFSClosure::find_leaks_from_edge(EdgeStore* edge_store,

                                      BitSet* mark_bits,

                                      const Edge* start_edge) {

  assert(edge_store != NULL, "invariant");

  assert(mark_bits != NULL," invariant");

  assert(start_edge != NULL, "invariant");

  _edge_store = edge_store;

  _mark_bits = mark_bits;

  _start_edge = start_edge;

  _ignore_root_set = false;

  assert(_max_depth == max_dfs_depth, "invariant");

  // Depth-first search, starting from a BFS egde

  DFSClosure dfs;

  start_edge->pointee()->oop_iterate(&dfs);

}

void DFSClosure::find_leaks_from_root_set(EdgeStore* edge_store,

                                          BitSet* mark_bits) {

  assert(edge_store != NULL, "invariant");

  assert(mark_bits != NULL, "invariant");

  _edge_store = edge_store;

  _mark_bits = mark_bits;

  _start_edge = NULL;

  // Mark root set, to avoid going sideways

  _max_depth = 1;

  _ignore_root_set = false;

  DFSClosure dfs1;

  RootSetClosure::process_roots(&dfs1);

  // Depth-first search

  _max_depth = max_dfs_depth;

  _ignore_root_set = true;

  assert(_start_edge == NULL, "invariant");

  DFSClosure dfs2;

  RootSetClosure::process_roots(&dfs2);

}

void DFSClosure::closure_impl(const oop* reference, const oop pointee) {

  assert(pointee != NULL, "invariant");

  assert(reference != NULL, "invariant");

  if (GranularTimer::is_finished()) {

     return;

  }

  if (_depth == 0 && _ignore_root_set) {

    // Root set is already marked, but we want

    // to continue, so skip is_marked check.

    assert(_mark_bits->is_marked(pointee), "invariant");

  } else {

    if (_mark_bits->is_marked(pointee)) {

      return;

    }

  }

  _reference = reference;

  _mark_bits->mark_obj(pointee);

  assert(_mark_bits->is_marked(pointee), "invariant");

  // is the pointee a sample object?

  if (NULL == pointee->mark()) {

    add_chain();

  }

  assert(_max_depth >= 1, "invariant");

  if (_depth < _max_depth - 1) {

    DFSClosure next_level(this, _depth + 1);

    pointee->oop_iterate(&next_level);

  }

}

void DFSClosure::add_chain() {

  const size_t length = _start_edge == NULL ? _depth + 1 :

                        _start_edge->distance_to_root() + 1 + _depth + 1;

  ResourceMark rm;

  Edge* const chain = NEW_RESOURCE_ARRAY(Edge, length);

  size_t idx = 0;

  // aggregate from depth-first search

  const DFSClosure* c = this;

  while (c != NULL) {

    chain[idx++] = Edge(NULL, c->reference());

    c = c->parent();

  }

  assert(idx == _depth + 1, "invariant");

  // aggregate from breadth-first search

  const Edge* current = _start_edge;

  while (current != NULL) {

    chain[idx++] = Edge(NULL, current->reference());

    current = current->parent();

  }

  assert(idx == length, "invariant");

  _edge_store->add_chain(chain, length);

}

void DFSClosure::do_oop(oop* ref) {

  assert(ref != NULL, "invariant");

  assert(is_aligned(ref, HeapWordSize), "invariant");

  const oop pointee = *ref;

  if (pointee != NULL) {

    closure_impl(ref, pointee);

  }

}

void DFSClosure::do_oop(narrowOop* ref) {

  assert(ref != NULL, "invariant");

  assert(is_aligned(ref, sizeof(narrowOop)), "invariant");

  const oop pointee = RawAccess<>::oop_load(ref);

  if (pointee != NULL) {

    closure_impl(UnifiedOop::encode(ref), pointee);

  }

}