1 /*
   2  * Copyright (c) 1997, 2015, 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.
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
  27 
  28 #include "gc_interface/collectedHeap.hpp"
  29 #include "memory/genOopClosures.hpp"
  30 #include "memory/iterator.hpp"
  31 #include "oops/markOop.hpp"
  32 #include "oops/oop.hpp"
  33 #include "runtime/timer.hpp"
  34 #include "utilities/growableArray.hpp"
  35 #include "utilities/stack.hpp"
  36 #include "utilities/taskqueue.hpp"
  37 
  38 class ReferenceProcessor;
  39 class DataLayout;
  40 class SerialOldTracer;
  41 class STWGCTimer;
  42 
  43 // MarkSweep takes care of global mark-compact garbage collection for a
  44 // GenCollectedHeap using a four-phase pointer forwarding algorithm.  All
  45 // generations are assumed to support marking; those that can also support
  46 // compaction.
  47 //
  48 // Class unloading will only occur when a full gc is invoked.
  49 
  50 // declared at end
  51 class PreservedMark;
  52 
  53 class MarkSweep : AllStatic {
  54   //
  55   // Inline closure decls
  56   //
  57   class FollowRootClosure: public OopsInGenClosure {
  58    public:
  59     virtual void do_oop(oop* p);
  60     virtual void do_oop(narrowOop* p);
  61   };
  62 
  63   class MarkAndPushClosure: public ExtendedOopClosure {
  64    public:
  65     template <typename T> void do_oop_nv(T* p);
  66     virtual void do_oop(oop* p);
  67     virtual void do_oop(narrowOop* p);
  68   };
  69 
  70   class FollowStackClosure: public VoidClosure {
  71    public:
  72     virtual void do_void();
  73   };
  74 
  75   class AdjustPointerClosure: public OopsInGenClosure {
  76    public:
  77     template <typename T> void do_oop_nv(T* p);
  78     virtual void do_oop(oop* p);
  79     virtual void do_oop(narrowOop* p);
  80 
  81     // This closure provides its own oop verification code.
  82     debug_only(virtual bool should_verify_oops() { return false; })
  83   };
  84 
  85   // Used for java/lang/ref handling
  86   class IsAliveClosure: public BoolObjectClosure {
  87    public:
  88     virtual bool do_object_b(oop p);
  89   };
  90 
  91   class KeepAliveClosure: public OopClosure {
  92    protected:
  93     template <class T> void do_oop_work(T* p);
  94    public:
  95     virtual void do_oop(oop* p);
  96     virtual void do_oop(narrowOop* p);
  97   };
  98 
  99   //
 100   // Friend decls
 101   //
 102   friend class AdjustPointerClosure;
 103   friend class KeepAliveClosure;
 104   friend class VM_MarkSweep;
 105   friend void marksweep_init();
 106 
 107   //
 108   // Vars
 109   //
 110  protected:
 111   // Total invocations of a MarkSweep collection
 112   static uint _total_invocations;
 113 
 114   // Traversal stacks used during phase1
 115   static Stack<oop, mtGC>                      _marking_stack;
 116   static Stack<ObjArrayTask, mtGC>             _objarray_stack;
 117 
 118   // Space for storing/restoring mark word
 119   static Stack<markOop, mtGC>                  _preserved_mark_stack;
 120   static Stack<oop, mtGC>                      _preserved_oop_stack;
 121   static size_t                          _preserved_count;
 122   static size_t                          _preserved_count_max;
 123   static PreservedMark*                  _preserved_marks;
 124 
 125   // Reference processing (used in ...follow_contents)
 126   static ReferenceProcessor*             _ref_processor;
 127 
 128   static STWGCTimer*                     _gc_timer;
 129   static SerialOldTracer*                _gc_tracer;
 130 
 131   // Non public closures
 132   static KeepAliveClosure keep_alive;
 133 
 134  public:
 135   // Public closures
 136   static IsAliveClosure       is_alive;
 137   static FollowRootClosure    follow_root_closure;
 138   static MarkAndPushClosure   mark_and_push_closure;
 139   static FollowStackClosure   follow_stack_closure;
 140   static CLDToOopClosure      follow_cld_closure;
 141   static AdjustPointerClosure adjust_pointer_closure;
 142   static CLDToOopClosure      adjust_cld_closure;
 143 
 144   // Accessors
 145   static uint total_invocations() { return _total_invocations; }
 146 
 147   // Reference Processing
 148   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
 149 
 150   static STWGCTimer* gc_timer() { return _gc_timer; }
 151   static SerialOldTracer* gc_tracer() { return _gc_tracer; }
 152 
 153   // Call backs for marking
 154   static void mark_object(oop obj);
 155   // Mark pointer and follow contents.  Empty marking stack afterwards.
 156   template <class T> static inline void follow_root(T* p);
 157 
 158   // Check mark and maybe push on marking stack
 159   template <class T> static void mark_and_push(T* p);
 160 
 161   static inline void push_objarray(oop obj, size_t index);
 162 
 163   static void follow_stack();   // Empty marking stack.
 164 
 165   static void follow_object(oop obj);
 166 
 167   static void follow_array(objArrayOop array, int index);
 168 
 169   static void follow_klass(Klass* klass);
 170 
 171   static void follow_class_loader(ClassLoaderData* cld);
 172 
 173   static int adjust_pointers(oop obj);
 174 
 175   static void preserve_mark(oop p, markOop mark);
 176                                 // Save the mark word so it can be restored later
 177   static void adjust_marks();   // Adjust the pointers in the preserved marks table
 178   static void restore_marks();  // Restore the marks that we saved in preserve_mark
 179 
 180   template <class T> static inline void adjust_pointer(T* p);
 181 };
 182 
 183 class PreservedMark VALUE_OBJ_CLASS_SPEC {
 184 private:
 185   oop _obj;
 186   markOop _mark;
 187 
 188 public:
 189   void init(oop obj, markOop mark) {
 190     _obj = obj;
 191     _mark = mark;
 192   }
 193 
 194   void adjust_pointer();
 195   void restore();
 196 };
 197 
 198 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP