1 /*
  2  * Copyright (c) 1997, 2019, 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_GC_SERIAL_MARKSWEEP_HPP
 26 #define SHARE_GC_SERIAL_MARKSWEEP_HPP
 27 
 28 #include "gc/shared/collectedHeap.hpp"
 29 #include "gc/shared/genOopClosures.hpp"
 30 #include "gc/shared/taskqueue.hpp"
 31 #include "memory/iterator.hpp"
 32 #include "oops/markWord.hpp"
 33 #include "oops/oop.hpp"
 34 #include "runtime/timer.hpp"
 35 #include "utilities/growableArray.hpp"
 36 #include "utilities/stack.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 class MarkAndPushClosure;
 53 
 54 class MarkSweep : AllStatic {
 55   //
 56   // Inline closure decls
 57   //
 58   class FollowRootClosure: public BasicOopIterateClosure {
 59    public:
 60     virtual void do_oop(oop* p);
 61     virtual void do_oop(narrowOop* p);
 62   };
 63 
 64   class FollowStackClosure: public VoidClosure {
 65    public:
 66     virtual void do_void();
 67   };
 68 
 69   // Used for java/lang/ref handling
 70   class IsAliveClosure: public BoolObjectClosure {
 71    public:
 72     virtual bool do_object_b(oop p);
 73   };
 74 
 75   class KeepAliveClosure: public OopClosure {
 76    protected:
 77     template <class T> void do_oop_work(T* p);
 78    public:
 79     virtual void do_oop(oop* p);
 80     virtual void do_oop(narrowOop* p);
 81   };
 82 
 83   //
 84   // Friend decls
 85   //
 86   friend class KeepAliveClosure;
 87   friend class VM_MarkSweep;
 88 
 89   //
 90   // Vars
 91   //
 92  protected:
 93   // Total invocations of a MarkSweep collection
 94   static uint _total_invocations;
 95 
 96   // Traversal stacks used during phase1
 97   static Stack<oop, mtGC>                      _marking_stack;
 98   static Stack<ObjArrayTask, mtGC>             _objarray_stack;
 99 
100   // Space for storing/restoring mark word
101   static Stack<markWord, mtGC>                 _preserved_mark_stack;
102   static Stack<oop, mtGC>                      _preserved_oop_stack;
103   static size_t                          _preserved_count;
104   static size_t                          _preserved_count_max;
105   static PreservedMark*                  _preserved_marks;
106 
107   // Reference processing (used in ...follow_contents)
108   static ReferenceProcessor*             _ref_processor;
109 
110   static STWGCTimer*                     _gc_timer;
111   static SerialOldTracer*                _gc_tracer;
112 
113   // Non public closures
114   static KeepAliveClosure keep_alive;
115 
116  public:
117   static void initialize();
118 
119   // Public closures
120   static IsAliveClosure       is_alive;
121   static FollowRootClosure    follow_root_closure;
122   static MarkAndPushClosure   mark_and_push_closure;
123   static FollowStackClosure   follow_stack_closure;
124   static CLDToOopClosure      follow_cld_closure;
125 
126   // Accessors
127   static uint total_invocations() { return _total_invocations; }
128 
129   // Reference Processing
130   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
131   static void set_ref_processor(ReferenceProcessor* rp);
132 
133   static STWGCTimer* gc_timer() { return _gc_timer; }
134   static SerialOldTracer* gc_tracer() { return _gc_tracer; }
135 
136   static void preserve_mark(oop p, markWord mark);
137                                 // Save the mark word so it can be restored later
138   template <bool ALT_FWD>
139   static void adjust_marks_impl();   // Adjust the pointers in the preserved marks table
140   static void adjust_marks();   // Adjust the pointers in the preserved marks table
141   static void restore_marks();  // Restore the marks that we saved in preserve_mark
142 
143   template <bool ALT_FWD>
144   static int adjust_pointers(oop obj);
145 
146   static void follow_stack();   // Empty marking stack.
147 
148   static void follow_klass(Klass* klass);
149 
150   static void follow_cld(ClassLoaderData* cld);
151 
152   template <bool ALT_FWD, class T>
153   static inline void adjust_pointer(T* p);
154 
155   // Check mark and maybe push on marking stack
156   template <class T> static void mark_and_push(T* p);
157 
158  private:
159   // Call backs for marking
160   static void mark_object(oop obj);
161   // Mark pointer and follow contents.  Empty marking stack afterwards.
162   template <class T> static inline void follow_root(T* p);
163 
164   static inline void push_objarray(oop obj, size_t index);
165 
166   static void follow_object(oop obj);
167 
168   static void follow_array(objArrayOop array);
169 
170   static void follow_array_chunk(objArrayOop array, int index);
171 };
172 
173 class MarkAndPushClosure: public OopIterateClosure {
174 public:
175   template <typename T> void do_oop_work(T* p);
176   virtual void do_oop(oop* p);
177   virtual void do_oop(narrowOop* p);
178 
179   virtual bool do_metadata() { return true; }
180   virtual void do_klass(Klass* k);
181   virtual void do_cld(ClassLoaderData* cld);
182 
183   void set_ref_discoverer(ReferenceDiscoverer* rd) {
184     set_ref_discoverer_internal(rd);
185   }
186 };
187 
188 template <bool ALT_FWD>
189 class AdjustPointerClosure: public BasicOopIterateClosure {
190  public:
191   template <typename T> void do_oop_work(T* p);
192   virtual void do_oop(oop* p);
193   virtual void do_oop(narrowOop* p);
194   virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
195 };
196 
197 class PreservedMark {
198 private:
199   oop _obj;
200   markWord _mark;
201 
202 public:
203   void init(oop obj, markWord mark) {
204     _obj = obj;
205     _mark = mark;
206   }
207 
208   template <bool ALT_FWD>
209   void adjust_pointer();
210   void restore();
211 };
212 
213 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP