1 /*
   2  * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_JFR_LEAKPROFILER_CHAINS_BFSCLOSURE_HPP
  26 #define SHARE_VM_JFR_LEAKPROFILER_CHAINS_BFSCLOSURE_HPP
  27 
  28 #include "memory/iterator.hpp"
  29 #include "oops/oop.hpp"
  30 
  31 class BitSet;
  32 class Edge;
  33 class EdgeStore;
  34 class EdgeQueue;
  35 
  36 // Class responsible for iterating the heap breadth-first
  37 class BFSClosure : public ExtendedOopClosure {
  38  private:
  39   EdgeQueue* _edge_queue;
  40   EdgeStore* _edge_store;
  41   BitSet* _mark_bits;
  42   const Edge* _current_parent;
  43   mutable size_t _current_frontier_level;
  44   mutable size_t _next_frontier_idx;
  45   mutable size_t _prev_frontier_idx;
  46   size_t _dfs_fallback_idx;
  47   bool _use_dfs;
  48 
  49   void log_completed_frontier() const;
  50   void log_dfs_fallback() const;
  51 
  52   bool is_complete() const;
  53   void step_frontier() const;
  54 
  55   void closure_impl(const oop* reference, const oop pointee);
  56   void add_chain(const oop* reference, const oop pointee);
  57   void dfs_fallback();
  58 
  59   void iterate(const Edge* parent);
  60   void process(const oop* reference, const oop pointee);
  61 
  62   void process_root_set();
  63   void process_queue();
  64 
  65  public:
  66   BFSClosure(EdgeQueue* edge_queue, EdgeStore* edge_store, BitSet* mark_bits);
  67   void process();
  68 
  69   virtual void do_oop(oop* ref);
  70   virtual void do_oop(narrowOop* ref);
  71 };
  72 
  73 #endif // SHARE_VM_JFR_LEAKPROFILER_CHAINS_BFSCLOSURE_HPP