1 /*
   2  * Copyright (c) 1997, 2013, 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
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  23  */
  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/universe.hpp"
  30 #include "oops/markOop.hpp"
  31 #include "oops/oop.hpp"
  32 #include "runtime/timer.hpp"
  33 #include "utilities/growableArray.hpp"
  34 #include "utilities/stack.hpp"
  35 #include "utilities/taskqueue.hpp"
  36 
  37 class ReferenceProcessor;
  38 class DataLayout;
  39 class SerialOldTracer;
  40 class STWGCTimer;
  41 
  42 // MarkSweep takes care of global mark-compact garbage collection for a
  43 // GenCollectedHeap using a four-phase pointer forwarding algorithm.  All
  44 // generations are assumed to support marking; those that can also support
  45 // compaction.
  46 //
  47 // Class unloading will only occur when a full gc is invoked.
  48 
  49 // declared at end
  50 class PreservedMark;
  51 
  52 class MarkSweep : AllStatic {
  53   //
  54   // Inline closure decls
  55   //
  56   class FollowRootClosure: public OopsInGenClosure {
  57    public:
  58     virtual void do_oop(oop* p);
  59     virtual void do_oop(narrowOop* p);
  60   };
  61 
  62   class MarkAndPushClosure: public OopClosure {
  63    public:
  64     virtual void do_oop(oop* p);
  65     virtual void do_oop(narrowOop* p);
  66   };
  67 
  68   // The one and only place to start following the classes.
  69   // Should only be applied to the ClassLoaderData klasses list.
  70   class FollowKlassClosure : public KlassClosure {
  71    public:
  72     void do_klass(Klass* klass);
  73   };
  74   class AdjustKlassClosure : public KlassClosure {
  75    public:
  76     void do_klass(Klass* klass);
  77   };
  78 
  79   class FollowStackClosure: public VoidClosure {
  80    public:
  81     virtual void do_void();
  82   };
  83 
  84   class AdjustPointerClosure: public OopsInGenClosure {
  85    public:
  86     virtual void do_oop(oop* p);
  87     virtual void do_oop(narrowOop* p);
  88   };
  89 
  90   // Used for java/lang/ref handling
  91   class IsAliveClosure: public BoolObjectClosure {
  92    public:
  93     virtual bool do_object_b(oop p);
  94   };
  95 
  96   class KeepAliveClosure: public OopClosure {
  97    protected:
  98     template <class T> void do_oop_work(T* p);
  99    public:
 100     virtual void do_oop(oop* p);
 101     virtual void do_oop(narrowOop* p);
 102   };
 103 
 104   //
 105   // Friend decls
 106   //
 107   friend class AdjustPointerClosure;
 108   friend class KeepAliveClosure;
 109   friend class VM_MarkSweep;
 110   friend void marksweep_init();
 111 
 112   //
 113   // Vars
 114   //
 115  protected:
 116   // Total invocations of a MarkSweep collection
 117   static uint _total_invocations;
 118 
 119   // Traversal stacks used during phase1
 120   static Stack<oop, mtGC>                      _marking_stack;
 121   static Stack<ObjArrayTask, mtGC>             _objarray_stack;
 122 
 123   // Space for storing/restoring mark word
 124   static Stack<markOop, mtGC>                  _preserved_mark_stack;
 125   static Stack<oop, mtGC>                      _preserved_oop_stack;
 126   static size_t                          _preserved_count;
 127   static size_t                          _preserved_count_max;
 128   static PreservedMark*                  _preserved_marks;
 129 
 130   // Reference processing (used in ...follow_contents)
 131   static ReferenceProcessor*             _ref_processor;
 132 
 133   static STWGCTimer*                     _gc_timer;
 134   static SerialOldTracer*                _gc_tracer;
 135 
 136   // Non public closures
 137   static KeepAliveClosure keep_alive;
 138 
 139   // Debugging
 140   static void trace(const char* msg) PRODUCT_RETURN;
 141 
 142  public:
 143   // Public closures
 144   static IsAliveClosure       is_alive;
 145   static FollowRootClosure    follow_root_closure;
 146   static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure
 147   static MarkAndPushClosure   mark_and_push_closure;
 148   static FollowKlassClosure   follow_klass_closure;
 149   static FollowStackClosure   follow_stack_closure;
 150   static AdjustPointerClosure adjust_pointer_closure;
 151   static AdjustKlassClosure   adjust_klass_closure;
 152 
 153   // Accessors
 154   static uint total_invocations() { return _total_invocations; }
 155 
 156   // Reference Processing
 157   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
 158 
 159   static STWGCTimer* gc_timer() { return _gc_timer; }
 160   static SerialOldTracer* gc_tracer() { return _gc_tracer; }
 161 
 162   // Call backs for marking
 163   static void mark_object(oop obj);
 164   // Mark pointer and follow contents.  Empty marking stack afterwards.
 165   template <class T> static inline void follow_root(T* p);
 166 
 167   // Check mark and maybe push on marking stack
 168   template <class T> static void mark_and_push(T* p);
 169 
 170   static inline void push_objarray(oop obj, size_t index);
 171 
 172   static void follow_stack();   // Empty marking stack.
 173 
 174   static void follow_klass(Klass* klass);
 175   static void adjust_klass(Klass* klass);
 176 
 177   static void follow_class_loader(ClassLoaderData* cld);
 178   static void adjust_class_loader(ClassLoaderData* cld);
 179 
 180   static void preserve_mark(oop p, markOop mark);
 181                                 // Save the mark word so it can be restored later
 182   static void adjust_marks();   // Adjust the pointers in the preserved marks table
 183   static void restore_marks();  // Restore the marks that we saved in preserve_mark
 184 
 185   template <class T> static inline void adjust_pointer(T* p);
 186 };
 187 
 188 class PreservedMark VALUE_OBJ_CLASS_SPEC {
 189 private:
 190   oop _obj;
 191   markOop _mark;
 192 
 193 public:
 194   void init(oop obj, markOop mark) {
 195     _obj = obj;
 196     _mark = mark;
 197   }
 198 
 199   void adjust_pointer() {
 200     MarkSweep::adjust_pointer(&_obj);
 201   }
 202 
 203   void restore() {
 204     _obj->set_mark(_mark);
 205   }
 206 };
 207 
 208 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP