--- /dev/null	2019-01-28 17:45:45.000000000 +0800
+++ new/src/share/vm/jfr/leakprofiler/chains/bfsClosure.cpp	2019-01-28 17:45:45.000000000 +0800
@@ -0,0 +1,239 @@
+/*
+ * Copyright (c) 2014, 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 "jfr/leakprofiler/chains/bitset.hpp"
+#include "jfr/leakprofiler/chains/bfsClosure.hpp"
+#include "jfr/leakprofiler/chains/dfsClosure.hpp"
+#include "jfr/leakprofiler/chains/edge.hpp"
+#include "jfr/leakprofiler/chains/edgeStore.hpp"
+#include "jfr/leakprofiler/chains/edgeQueue.hpp"
+#include "jfr/leakprofiler/utilities/granularTimer.hpp"
+#include "jfr/leakprofiler/utilities/unifiedOop.hpp"
+#include "memory/resourceArea.hpp"
+#include "jfr/utilities/align.hpp"
+
+BFSClosure::BFSClosure(EdgeQueue* edge_queue, EdgeStore* edge_store, BitSet* mark_bits) :
+  _edge_queue(edge_queue),
+  _edge_store(edge_store),
+  _mark_bits(mark_bits),
+  _current_parent(NULL),
+  _current_frontier_level(0),
+  _next_frontier_idx(0),
+  _prev_frontier_idx(0),
+  _dfs_fallback_idx(0),
+  _use_dfs(false) {
+}
+
+static void log_frontier_level_summary(size_t level,
+                                       size_t high_idx,
+                                       size_t low_idx,
+                                       size_t edge_size) {
+  const size_t nof_edges_in_frontier = high_idx - low_idx;
+  log_trace(jfr, system)(
+      "BFS front: " SIZE_FORMAT " edges: " SIZE_FORMAT " size: " SIZE_FORMAT " [KB]",
+      level,
+      nof_edges_in_frontier,
+      (nof_edges_in_frontier * edge_size) / K
+                        );
+}
+
+void BFSClosure::log_completed_frontier() const {
+  log_frontier_level_summary(_current_frontier_level,
+                             _next_frontier_idx,
+                             _prev_frontier_idx,
+                             _edge_queue->sizeof_edge());
+}
+
+void BFSClosure::log_dfs_fallback() const {
+  const size_t edge_size = _edge_queue->sizeof_edge();
+  // first complete summary for frontier in progress
+  log_frontier_level_summary(_current_frontier_level,
+                             _next_frontier_idx,
+                             _prev_frontier_idx,
+                             edge_size);
+
+  // and then also complete the last frontier
+  log_frontier_level_summary(_current_frontier_level + 1,
+                             _edge_queue->bottom(),
+                             _next_frontier_idx,
+                             edge_size);
+
+  // additional information about DFS fallover
+  log_trace(jfr, system)(
+      "BFS front: " SIZE_FORMAT " filled edge queue at edge: " SIZE_FORMAT,
+      _current_frontier_level,
+      _dfs_fallback_idx
+                        );
+
+  const size_t nof_dfs_completed_edges = _edge_queue->bottom() - _dfs_fallback_idx;
+  log_trace(jfr, system)(
+      "DFS to complete " SIZE_FORMAT " edges size: " SIZE_FORMAT " [KB]",
+      nof_dfs_completed_edges,
+      (nof_dfs_completed_edges * edge_size) / K
+                        );
+}
+
+void BFSClosure::process() {
+
+  process_root_set();
+  process_queue();
+}
+
+void BFSClosure::process_root_set() {
+  for (size_t idx = _edge_queue->bottom(); idx < _edge_queue->top(); ++idx) {
+    const Edge* edge = _edge_queue->element_at(idx);
+    assert(edge->parent() == NULL, "invariant");
+    process(edge->reference(), edge->pointee());
+  }
+}
+
+void BFSClosure::process(const oop* reference, const oop pointee) {
+  closure_impl(reference, pointee);
+}
+void BFSClosure::closure_impl(const oop* reference, const oop pointee) {
+  assert(reference != NULL, "invariant");
+  assert(UnifiedOop::dereference(reference) == pointee, "invariant");
+
+  if (GranularTimer::is_finished()) {
+     return;
+  }
+
+  if (_use_dfs) {
+    assert(_current_parent != NULL, "invariant");
+    DFSClosure::find_leaks_from_edge(_edge_store, _mark_bits, _current_parent);
+    return;
+  }
+
+  if (!_mark_bits->is_marked(pointee)) {
+    _mark_bits->mark_obj(pointee);
+    // is the pointee a sample object?
+    if (NULL == pointee->mark()) {
+      add_chain(reference, pointee);
+    }
+
+    // if we are processinig initial root set, don't add to queue
+    if (_current_parent != NULL) {
+      assert(_current_parent->distance_to_root() == _current_frontier_level, "invariant");
+      _edge_queue->add(_current_parent, reference);
+    }
+
+    if (_edge_queue->is_full()) {
+      dfs_fallback();
+    }
+  }
+}
+
+void BFSClosure::add_chain(const oop* reference, const oop pointee) {
+  assert(pointee != NULL, "invariant");
+  assert(NULL == pointee->mark(), "invariant");
+
+  const size_t length = _current_parent == NULL ? 1 : _current_parent->distance_to_root() + 2;
+  ResourceMark rm;
+  Edge* const chain = NEW_RESOURCE_ARRAY(Edge, length);
+  size_t idx = 0;
+  chain[idx++] = Edge(NULL, reference);
+  // aggregate from breadth-first search
+  const Edge* current = _current_parent;
+  while (current != NULL) {
+    chain[idx++] = Edge(NULL, current->reference());
+    current = current->parent();
+  }
+  assert(length == idx, "invariant");
+  _edge_store->add_chain(chain, length);
+}
+
+void BFSClosure::dfs_fallback() {
+  assert(_edge_queue->is_full(), "invariant");
+  _use_dfs = true;
+  _dfs_fallback_idx = _edge_queue->bottom();
+  while (!_edge_queue->is_empty()) {
+    const Edge* edge = _edge_queue->remove();
+    if (edge->pointee() != NULL) {
+      DFSClosure::find_leaks_from_edge(_edge_store, _mark_bits, edge);
+    }
+  }
+}
+
+void BFSClosure::process_queue() {
+  assert(_current_frontier_level == 0, "invariant");
+  assert(_next_frontier_idx == 0, "invariant");
+  assert(_prev_frontier_idx == 0, "invariant");
+
+  _next_frontier_idx = _edge_queue->top();
+  while (!is_complete()) {
+    iterate(_edge_queue->remove()); // edge_queue.remove() increments bottom
+  }
+}
+
+void BFSClosure::step_frontier() const {
+  log_completed_frontier();
+  ++_current_frontier_level;
+  _prev_frontier_idx = _next_frontier_idx;
+  _next_frontier_idx = _edge_queue->top();
+}
+
+bool BFSClosure::is_complete() const {
+  if (_edge_queue->bottom() < _next_frontier_idx) {
+    return false;
+  }
+  if (_edge_queue->bottom() > _next_frontier_idx) {
+    // fallback onto DFS as part of processing the frontier
+    assert(_dfs_fallback_idx >= _prev_frontier_idx, "invariant");
+    assert(_dfs_fallback_idx < _next_frontier_idx, "invariant");
+    log_dfs_fallback();
+    return true;
+  }
+  assert(_edge_queue->bottom() == _next_frontier_idx, "invariant");
+  if (_edge_queue->is_empty()) {
+    return true;
+  }
+  step_frontier();
+  return false;
+}
+
+void BFSClosure::iterate(const Edge* parent) {
+  assert(parent != NULL, "invariant");
+  const oop pointee = parent->pointee();
+  assert(pointee != NULL, "invariant");
+  _current_parent = parent;
+  pointee->oop_iterate(this);
+}
+
+void BFSClosure::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 BFSClosure::do_oop(narrowOop* ref) {
+  assert(ref != NULL, "invariant");
+  assert(is_aligned(ref, sizeof(narrowOop)), "invariant");
+  const oop pointee = oopDesc::load_decode_heap_oop(ref);
+  if (pointee != NULL) {
+    closure_impl(UnifiedOop::encode(ref), pointee);
+  }
+}