jdk8-mips64-public/hotspot: src/share/vm/memory/iterator.hpp@05f89f00a864 (annotated)

src/share/vm/memory/iterator.hpp@05f89f00a864 (annotated)

src/share/vm/memory/iterator.hpp

Mon, 24 Aug 2009 10:36:31 -0700

author: jmasa
date: Mon, 24 Aug 2009 10:36:31 -0700
changeset 1370: 05f89f00a864
parent 791: 1ee8caae33af
child 1376: 8b46c4d82093
permissions: -rw-r--r--

6798898: CMS: bugs related to class unloading
Summary: Override should_remember_klasses() and remember_klass() as needed.
Reviewed-by: ysr, jcoomes

 /*
  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // The following classes are C++ `closures` for iterating over objects, roots and spaces
 class ReferenceProcessor;
 // Closure provides abortability.
 class Closure : public StackObj {
  protected:
   bool _abort;
   void set_abort() { _abort = true; }
  public:
   Closure() : _abort(false) {}
   // A subtype can use this mechanism to indicate to some iterator mapping
   // functions that the iteration should cease.
   bool abort() { return _abort; }
   void clear_abort() { _abort = false; }
 };
 // OopClosure is used for iterating through roots (oop*)
 class OopClosure : public Closure {
  public:
   ReferenceProcessor* _ref_processor;
   OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
   OopClosure() : _ref_processor(NULL) { }
   virtual void do_oop(oop* o) = 0;
   virtual void do_oop_v(oop* o) { do_oop(o); }
   virtual void do_oop(narrowOop* o) = 0;
   virtual void do_oop_v(narrowOop* o) { do_oop(o); }
   // In support of post-processing of weak links of KlassKlass objects;
   // see KlassKlass::oop_oop_iterate().
   virtual const bool should_remember_klasses() const {
     assert(!must_remember_klasses(), "Should have overriden this method.");
     return false;
   }
   virtual void remember_klass(Klass* k) { /* do nothing */ }
   // If "true", invoke on nmethods (when scanning compiled frames).
   virtual const bool do_nmethods() const { return false; }
   // The methods below control how object iterations invoking this closure
   // should be performed:
   // If "true", invoke on header klass field.
   bool do_header() { return true; } // Note that this is non-virtual.
   // Controls how prefetching is done for invocations of this closure.
   Prefetch::style prefetch_style() { // Note that this is non-virtual.
     return Prefetch::do_none;
   }
   // True iff this closure may be safely applied more than once to an oop
   // location without an intervening "major reset" (like the end of a GC).
   virtual bool idempotent() { return false; }
   virtual bool apply_to_weak_ref_discovered_field() { return false; }
 #ifdef ASSERT
   static bool _must_remember_klasses;
   static bool must_remember_klasses();
   static void set_must_remember_klasses(bool v);
 #endif
 };
 // ObjectClosure is used for iterating through an object space
 class ObjectClosure : public Closure {
  public:
   // Called for each object.
   virtual void do_object(oop obj) = 0;
 };
 class BoolObjectClosure : public ObjectClosure {
  public:
   virtual bool do_object_b(oop obj) = 0;
 };
 // Applies an oop closure to all ref fields in objects iterated over in an
 // object iteration.
 class ObjectToOopClosure: public ObjectClosure {
   OopClosure* _cl;
 public:
   void do_object(oop obj);
   ObjectToOopClosure(OopClosure* cl) : _cl(cl) {}
 };
 // A version of ObjectClosure with "memory" (see _previous_address below)
 class UpwardsObjectClosure: public BoolObjectClosure {
   HeapWord* _previous_address;
  public:
   UpwardsObjectClosure() : _previous_address(NULL) { }
   void set_previous(HeapWord* addr) { _previous_address = addr; }
   HeapWord* previous()              { return _previous_address; }
   // A return value of "true" can be used by the caller to decide
   // if this object's end should *NOT* be recorded in
   // _previous_address above.
   virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
 };
 // A version of ObjectClosure that is expected to be robust
 // in the face of possibly uninitialized objects.
 class ObjectClosureCareful : public ObjectClosure {
  public:
   virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
   virtual size_t do_object_careful(oop p) = 0;
 };
 // The following are used in CompactibleFreeListSpace and
 // ConcurrentMarkSweepGeneration.
 // Blk closure (abstract class)
 class BlkClosure : public StackObj {
  public:
   virtual size_t do_blk(HeapWord* addr) = 0;
 };
 // A version of BlkClosure that is expected to be robust
 // in the face of possibly uninitialized objects.
 class BlkClosureCareful : public BlkClosure {
  public:
   size_t do_blk(HeapWord* addr) {
     guarantee(false, "call do_blk_careful instead");
     return 0;
   }
   virtual size_t do_blk_careful(HeapWord* addr) = 0;
 };
 // SpaceClosure is used for iterating over spaces
 class Space;
 class CompactibleSpace;
 class SpaceClosure : public StackObj {
  public:
   // Called for each space
   virtual void do_space(Space* s) = 0;
 };
 class CompactibleSpaceClosure : public StackObj {
  public:
   // Called for each compactible space
   virtual void do_space(CompactibleSpace* s) = 0;
 };
 // MonitorClosure is used for iterating over monitors in the monitors cache
 class ObjectMonitor;
 class MonitorClosure : public StackObj {
  public:
   // called for each monitor in cache
   virtual void do_monitor(ObjectMonitor* m) = 0;
 };
 // A closure that is applied without any arguments.
 class VoidClosure : public StackObj {
  public:
   // I would have liked to declare this a pure virtual, but that breaks
   // in mysterious ways, for unknown reasons.
   virtual void do_void();
 };
 // YieldClosure is intended for use by iteration loops
 // to incrementalize their work, allowing interleaving
 // of an interruptable task so as to allow other
 // threads to run (which may not otherwise be able to access
 // exclusive resources, for instance). Additionally, the
 // closure also allows for aborting an ongoing iteration
 // by means of checking the return value from the polling
 // call.
 class YieldClosure : public StackObj {
   public:
    virtual bool should_return() = 0;
 };
 // Abstract closure for serializing data (read or write).
 class SerializeOopClosure : public OopClosure {
 public:
   // Return bool indicating whether closure implements read or write.
   virtual bool reading() const = 0;
   // Read/write the int pointed to by i.
   virtual void do_int(int* i) = 0;
   // Read/write the size_t pointed to by i.
   virtual void do_size_t(size_t* i) = 0;
   // Read/write the void pointer pointed to by p.
   virtual void do_ptr(void** p) = 0;
   // Read/write the HeapWord pointer pointed to be p.
   virtual void do_ptr(HeapWord** p) = 0;
   // Read/write the region specified.
   virtual void do_region(u_char* start, size_t size) = 0;
   // Check/write the tag.  If reading, then compare the tag against
   // the passed in value and fail is they don't match.  This allows
   // for verification that sections of the serialized data are of the
   // correct length.
   virtual void do_tag(int tag) = 0;
 };
 #ifdef ASSERT
 // This class is used to flag phases of a collection that
 // can unload classes and which should override the
 // should_remember_klasses() and remember_klass() of OopClosure.
 // The _must_remember_klasses is set in the contructor and restored
 // in the destructor.  _must_remember_klasses is checked in assertions
 // in the OopClosure implementations of should_remember_klasses() and
 // remember_klass() and the expectation is that the OopClosure
 // implementation should not be in use if _must_remember_klasses is set.
 // Instances of RememberKlassesChecker can be place in
 // marking phases of collections which can do class unloading.
 // RememberKlassesChecker can be passed "false" to turn off checking.
 // It is used by CMS when CMS yields to a different collector.
 class RememberKlassesChecker: StackObj {
  bool _state;
  bool _skip;
  public:
   RememberKlassesChecker(bool checking_on) : _state(false), _skip(false) {
     _skip = !(ClassUnloading && !UseConcMarkSweepGC ||
               CMSClassUnloadingEnabled && UseConcMarkSweepGC);
     if (_skip) {
       return;
     }
     _state = OopClosure::must_remember_klasses();
     OopClosure::set_must_remember_klasses(checking_on);
   }
   ~RememberKlassesChecker() {
     if (_skip) {
       return;
     }
     OopClosure::set_must_remember_klasses(_state);
   }
 };
 #endif  // ASSERT

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/iterator.hpp@05f89f00a864 (annotated)

src/share/vm/memory/iterator.hpp