1 /*
   2  * Copyright (c) 2015, 2017, 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 #ifndef SHARE_GC_Z_ZREFERENCEPROCESSOR_HPP
  25 #define SHARE_GC_Z_ZREFERENCEPROCESSOR_HPP
  26 
  27 #include "gc/shared/referenceDiscoverer.hpp"
  28 #include "gc/z/zValue.hpp"
  29 
  30 class ReferencePolicy;
  31 class ZWorkers;
  32 
  33 class ZReferenceProcessor : public ReferenceDiscoverer {
  34   friend class ZReferenceProcessorTask;
  35 
  36 private:
  37   typedef size_t Counters[REF_COUNT];
  38 
  39   ZWorkers* const      _workers;
  40   ReferencePolicy*     _soft_reference_policy;
  41   ZPerWorker<Counters> _encountered_count;
  42   ZPerWorker<Counters> _discovered_count;
  43   ZPerWorker<Counters> _enqueued_count;
  44   ZPerWorker<oop>      _discovered_list;
  45   ZContended<oop>      _pending_list;
  46   oop*                 _pending_list_tail;
  47 
  48   void update_soft_reference_clock() const;
  49 
  50   ReferenceType reference_type(oop obj) const;
  51   volatile oop* reference_referent_addr(oop obj) const;
  52   oop reference_referent(oop obj) const;
  53   bool is_reference_inactive(oop obj) const;
  54   bool is_referent_alive_or_null(oop obj, ReferenceType type) const;
  55   bool is_referent_softly_alive(oop obj, ReferenceType type) const;
  56   bool should_drop_reference(oop obj, ReferenceType type) const;
  57   bool should_mark_referent(ReferenceType type) const;
  58   bool should_clear_referent(ReferenceType type) const;
  59   void keep_referent_alive(oop obj, ReferenceType type) const;
  60 
  61   void discover(oop obj, ReferenceType type);
  62   oop drop(oop obj, ReferenceType type);
  63   oop* keep(oop obj, ReferenceType type);
  64 
  65   bool is_empty() const;
  66 
  67   void work();
  68   void collect_statistics();
  69 
  70   void process_references();
  71   void enqueue_references();
  72 
  73 public:
  74   ZReferenceProcessor(ZWorkers* workers);
  75 
  76   void set_soft_reference_policy(bool clear);
  77   void reset_statistics();
  78   virtual bool discover_reference(oop reference, ReferenceType type);
  79   void process_and_enqueue_references();
  80 };
  81 
  82 #endif // SHARE_GC_Z_ZREFERENCEPROCESSOR_HPP