1 /*
   2  * Copyright (c) 2016, 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_GC_SHARED_PRESERVEDMARKS_HPP
  26 #define SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "memory/padded.hpp"
  30 #include "oops/oop.hpp"
  31 #include "utilities/stack.hpp"
  32 
  33 class PreservedMarksSet;
  34 class WorkGang;
  35 
  36 class PreservedMarks VALUE_OBJ_CLASS_SPEC {
  37 private:
  38   class OopAndMarkOop {
  39   private:
  40     oop _o;
  41     markOop _m;
  42 
  43   public:
  44     OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { }
  45 
  46     void set_mark() const {
  47       _o->set_mark(_m);
  48     }
  49   };
  50   typedef Stack<OopAndMarkOop, mtGC> OopAndMarkOopStack;
  51 
  52   OopAndMarkOopStack _stack;
  53 
  54   inline bool should_preserve_mark(oop obj, markOop m) const;
  55   inline void push(oop obj, markOop m);
  56 
  57 public:
  58   size_t size() const { return _stack.size(); }
  59   inline void push_if_necessary(oop obj, markOop m);
  60   // Iterate over the stack, restore all preserved marks, and
  61   // reclaim the memory taken up by the stack segments.
  62   void restore();
  63 
  64   void restore_and_increment(volatile size_t* const _total_size_addr);
  65   inline static void init_forwarded_mark(oop obj);
  66 
  67   // Assert the stack is empty and has no cached segments.
  68   void assert_empty() PRODUCT_RETURN;
  69 
  70   inline PreservedMarks();
  71   ~PreservedMarks() { assert_empty(); }
  72 };
  73 
  74 class RemoveForwardedPointerClosure: public ObjectClosure {
  75 public:
  76   virtual void do_object(oop obj);
  77 };
  78 
  79 class RestorePreservedMarksTaskExecutor {
  80 public:
  81   void virtual restore(PreservedMarksSet* preserved_marks_set,
  82                        volatile size_t* total_size_addr) = 0;
  83 };
  84 
  85 class SharedRestorePreservedMarksTaskExecutor : public RestorePreservedMarksTaskExecutor {
  86 private:
  87     WorkGang* _workers;
  88 
  89 public:
  90     SharedRestorePreservedMarksTaskExecutor(WorkGang* workers) : _workers(workers) { }
  91 
  92     void restore(PreservedMarksSet* preserved_marks_set,
  93                  volatile size_t* total_size_addr);
  94 
  95 };
  96 
  97 class PreservedMarksSet : public CHeapObj<mtGC> {
  98 private:
  99   // true -> _stacks will be allocated in the C heap
 100   // false -> _stacks will be allocated in the resource arena
 101   const bool _in_c_heap;
 102 
 103   // Number of stacks we have allocated (typically, one stack per GC worker).
 104   // This should be >= 1 if the stacks have been initialized,
 105   // or == 0 if they have not.
 106   uint _num;
 107 
 108   // Stack array (typically, one stack per GC worker) of length _num.
 109   // This should be != NULL if the stacks have been initialized,
 110   // or == NULL if they have not.
 111   Padded<PreservedMarks>* _stacks;
 112 
 113 public:
 114   uint num() const { return _num; }
 115 
 116   // Return the i'th stack.
 117   PreservedMarks* get(uint i = 0) const {
 118     assert(_num > 0 && _stacks != NULL, "stacks should have been initialized");
 119     assert(i < _num, "pre-condition");
 120     return (_stacks + i);
 121   }
 122 
 123   // Allocate stack array.
 124   void init(uint num);
 125 
 126   // Iterate over all stacks, restore all preserved marks, and reclaim
 127   // the memory taken up by the stack segments.
 128   // Supported executors: SharedRestorePreservedMarksTaskExecutor (Serial, CMS, G1),
 129   // PSRestorePreservedMarksTaskExecutor (PS).
 130   inline void restore(RestorePreservedMarksTaskExecutor* executor);
 131 
 132   // Reclaim stack array.
 133   void reclaim();
 134 
 135   // Assert all the stacks are empty and have no cached segments.
 136   void assert_empty() PRODUCT_RETURN;
 137 
 138   PreservedMarksSet(bool in_c_heap)
 139       : _in_c_heap(in_c_heap), _num(0), _stacks(NULL) { }
 140 
 141   ~PreservedMarksSet() {
 142     assert(_stacks == NULL && _num == 0, "stacks should have been reclaimed");
 143   }
 144 };
 145 
 146 #endif // SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP