1 /*

     2  * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 // The following classes are C++ `closures` for iterating over objects, roots and spaces

    26 

    27 class ReferenceProcessor;

    28 

    29 // OopClosure is used for iterating through roots (oop*)

    30 

    31 class OopClosure : public StackObj {

    32  public:

    33   ReferenceProcessor* _ref_processor;

    34   OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }

    35   OopClosure() : _ref_processor(NULL) { }

    36   virtual void do_oop(oop* o) = 0;

    37   virtual void do_oop_v(oop* o) { do_oop(o); }

    38 

    39   // In support of post-processing of weak links of KlassKlass objects;

    40   // see KlassKlass::oop_oop_iterate().

    41   virtual const bool should_remember_klasses() const { return false;    }

    42   virtual void remember_klass(Klass* k) { /* do nothing */ }

    43 

    44   // If "true", invoke on nmethods (when scanning compiled frames).

    45   virtual const bool do_nmethods() const { return false; }

    46 

    47   // The methods below control how object iterations invoking this closure

    48   // should be performed:

    49 

    50   // If "true", invoke on header klass field.

    51   bool do_header() { return true; } // Note that this is non-virtual.

    52   // Controls how prefetching is done for invocations of this closure.

    53   Prefetch::style prefetch_style() { // Note that this is non-virtual.

    54     return Prefetch::do_none;

    55   }

    56 };

    57 

    58 // ObjectClosure is used for iterating through an object space

    59 

    60 class ObjectClosure : public StackObj {

    61  public:

    62   // Called for each object.

    63   virtual void do_object(oop obj) = 0;

    64 };

    65 

    66 

    67 class BoolObjectClosure : public ObjectClosure {

    68  public:

    69   virtual bool do_object_b(oop obj) = 0;

    70 };

    71 

    72 // Applies an oop closure to all ref fields in objects iterated over in an

    73 // object iteration.

    74 class ObjectToOopClosure: public ObjectClosure {

    75   OopClosure* _cl;

    76 public:

    77   void do_object(oop obj);

    78   ObjectToOopClosure(OopClosure* cl) : _cl(cl) {}

    79 };

    80 

    81 // A version of ObjectClosure with "memory" (see _previous_address below)

    82 class UpwardsObjectClosure: public BoolObjectClosure {

    83   HeapWord* _previous_address;

    84  public:

    85   UpwardsObjectClosure() : _previous_address(NULL) { }

    86   void set_previous(HeapWord* addr) { _previous_address = addr; }

    87   HeapWord* previous()              { return _previous_address; }

    88   // A return value of "true" can be used by the caller to decide

    89   // if this object's end should *NOT* be recorded in

    90   // _previous_address above.

    91   virtual bool do_object_bm(oop obj, MemRegion mr) = 0;

    92 };

    93 

    94 // A version of ObjectClosure that is expected to be robust

    95 // in the face of possibly uninitialized objects.

    96 class ObjectClosureCareful : public ObjectClosure {

    97  public:

    98   virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;

    99   virtual size_t do_object_careful(oop p) = 0;

   100 };

   101 

   102 // The following are used in CompactibleFreeListSpace and

   103 // ConcurrentMarkSweepGeneration.

   104 

   105 // Blk closure (abstract class)

   106 class BlkClosure : public StackObj {

   107  public:

   108   virtual size_t do_blk(HeapWord* addr) = 0;

   109 };

   110 

   111 // A version of BlkClosure that is expected to be robust

   112 // in the face of possibly uninitialized objects.

   113 class BlkClosureCareful : public BlkClosure {

   114  public:

   115   size_t do_blk(HeapWord* addr) {

   116     guarantee(false, "call do_blk_careful instead");

   117     return 0;

   118   }

   119   virtual size_t do_blk_careful(HeapWord* addr) = 0;

   120 };

   121 

   122 // SpaceClosure is used for iterating over spaces

   123 

   124 class Space;

   125 class CompactibleSpace;

   126 

   127 class SpaceClosure : public StackObj {

   128  public:

   129   // Called for each space

   130   virtual void do_space(Space* s) = 0;

   131 };

   132 

   133 class CompactibleSpaceClosure : public StackObj {

   134  public:

   135   // Called for each compactible space

   136   virtual void do_space(CompactibleSpace* s) = 0;

   137 };

   138 

   139 

   140 

   141 // MonitorClosure is used for iterating over monitors in the monitors cache

   142 

   143 class ObjectMonitor;

   144 

   145 class MonitorClosure : public StackObj {

   146  public:

   147   // called for each monitor in cache

   148   virtual void do_monitor(ObjectMonitor* m) = 0;

   149 };

   150 

   151 // A closure that is applied without any arguments.

   152 class VoidClosure : public StackObj {

   153  public:

   154   // I would have liked to declare this a pure virtual, but that breaks

   155   // in mysterious ways, for unknown reasons.

   156   virtual void do_void();

   157 };

   158 

   159 

   160 // YieldClosure is intended for use by iteration loops

   161 // to incrementalize their work, allowing interleaving

   162 // of an interruptable task so as to allow other

   163 // threads to run (which may not otherwise be able to access

   164 // exclusive resources, for instance). Additionally, the

   165 // closure also allows for aborting an ongoing iteration

   166 // by means of checking the return value from the polling

   167 // call.

   168 class YieldClosure : public StackObj {

   169   public:

   170    virtual bool should_return() = 0;

   171 };

   172 

   173 // Abstract closure for serializing data (read or write).

   174 

   175 class SerializeOopClosure : public OopClosure {

   176 public:

   177   // Return bool indicating whether closure implements read or write.

   178   virtual bool reading() const = 0;

   179 

   180   // Read/write the int pointed to by i.

   181   virtual void do_int(int* i) = 0;

   182 

   183   // Read/write the size_t pointed to by i.

   184   virtual void do_size_t(size_t* i) = 0;

   185 

   186   // Read/write the void pointer pointed to by p.

   187   virtual void do_ptr(void** p) = 0;

   188 

   189   // Read/write the HeapWord pointer pointed to be p.

   190   virtual void do_ptr(HeapWord** p) = 0;

   191 

   192   // Read/write the region specified.

   193   virtual void do_region(u_char* start, size_t size) = 0;

   194 

   195   // Check/write the tag.  If reading, then compare the tag against

   196   // the passed in value and fail is they don't match.  This allows

   197   // for verification that sections of the serialized data are of the

   198   // correct length.

   199   virtual void do_tag(int tag) = 0;

   200 };