src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp

Thu, 22 Sep 2011 10:57:37 -0700

author
johnc
date
Thu, 22 Sep 2011 10:57:37 -0700
changeset 3175
4dfb2df418f2
parent 2314
f95d63e2154a
child 6231
889068b9a088
permissions
-rw-r--r--

6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

     1 /*
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     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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     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
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     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).
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    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP
    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP
    28 #include "memory/genOopClosures.hpp"
    29 #include "memory/generation.hpp"
    30 #include "runtime/os.hpp"
    31 #include "utilities/taskqueue.hpp"
    33 // A BufferingOops closure tries to separate out the cost of finding roots
    34 // from the cost of applying closures to them.  It maintains an array of
    35 // ref-containing locations.  Until the array is full, applying the closure
    36 // to an oop* merely records that location in the array.  Since this
    37 // closure app cost is small, an elapsed timer can approximately attribute
    38 // all of this cost to the cost of finding the roots.  When the array fills
    39 // up, the wrapped closure is applied to all elements, keeping track of
    40 // this elapsed time of this process, and leaving the array empty.
    41 // The caller must be sure to call "done" to process any unprocessed
    42 // buffered entriess.
    44 class Generation;
    45 class HeapRegion;
    47 class BufferingOopClosure: public OopClosure {
    48 protected:
    49   enum PrivateConstants {
    50     BufferLength = 1024
    51   };
    53   StarTask  _buffer[BufferLength];
    54   StarTask* _buffer_top;
    55   StarTask* _buffer_curr;
    57   OopClosure* _oc;
    58   double      _closure_app_seconds;
    60   void process_buffer () {
    61     double start = os::elapsedTime();
    62     for (StarTask* curr = _buffer; curr < _buffer_curr; ++curr) {
    63       if (curr->is_narrow()) {
    64         assert(UseCompressedOops, "Error");
    65         _oc->do_oop((narrowOop*)(*curr));
    66       } else {
    67         _oc->do_oop((oop*)(*curr));
    68       }
    69     }
    70     _buffer_curr = _buffer;
    71     _closure_app_seconds += (os::elapsedTime() - start);
    72   }
    74   template <class T> inline void do_oop_work(T* p) {
    75     if (_buffer_curr == _buffer_top) {
    76       process_buffer();
    77     }
    78     StarTask new_ref(p);
    79     *_buffer_curr = new_ref;
    80     ++_buffer_curr;
    81   }
    83 public:
    84   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
    85   virtual void do_oop(oop* p)       { do_oop_work(p); }
    87   void done () {
    88     if (_buffer_curr > _buffer) {
    89       process_buffer();
    90     }
    91   }
    92   double closure_app_seconds () {
    93     return _closure_app_seconds;
    94   }
    95   BufferingOopClosure (OopClosure *oc) :
    96     _oc(oc),
    97     _buffer_curr(_buffer), _buffer_top(_buffer + BufferLength),
    98     _closure_app_seconds(0.0) { }
    99 };
   101 class BufferingOopsInGenClosure: public OopsInGenClosure {
   102   BufferingOopClosure _boc;
   103   OopsInGenClosure* _oc;
   104  protected:
   105   template <class T> inline void do_oop_work(T* p) {
   106     assert(generation()->is_in_reserved((void*)p), "Must be in!");
   107     _boc.do_oop(p);
   108   }
   109  public:
   110   BufferingOopsInGenClosure(OopsInGenClosure *oc) :
   111     _boc(oc), _oc(oc) {}
   113   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
   114   virtual void do_oop(oop* p)       { do_oop_work(p); }
   116   void done() {
   117     _boc.done();
   118   }
   120   double closure_app_seconds () {
   121     return _boc.closure_app_seconds();
   122   }
   124   void set_generation(Generation* gen) {
   125     OopsInGenClosure::set_generation(gen);
   126     _oc->set_generation(gen);
   127   }
   129   void reset_generation() {
   130     // Make sure we finish the current work with the current generation.
   131     _boc.done();
   132     OopsInGenClosure::reset_generation();
   133     _oc->reset_generation();
   134   }
   136 };
   139 class BufferingOopsInHeapRegionClosure: public OopsInHeapRegionClosure {
   140 private:
   141   enum PrivateConstants {
   142     BufferLength = 1024
   143   };
   145   StarTask     _buffer[BufferLength];
   146   StarTask*    _buffer_top;
   147   StarTask*    _buffer_curr;
   149   HeapRegion*  _hr_buffer[BufferLength];
   150   HeapRegion** _hr_curr;
   152   OopsInHeapRegionClosure*  _oc;
   153   double                    _closure_app_seconds;
   155   void process_buffer () {
   157     assert((_hr_curr - _hr_buffer) == (_buffer_curr - _buffer),
   158            "the two lengths should be the same");
   160     double start = os::elapsedTime();
   161     HeapRegion** hr_curr = _hr_buffer;
   162     HeapRegion*  hr_prev = NULL;
   163     for (StarTask* curr = _buffer; curr < _buffer_curr; ++curr) {
   164       HeapRegion* region = *hr_curr;
   165       if (region != hr_prev) {
   166         _oc->set_region(region);
   167         hr_prev = region;
   168       }
   169       if (curr->is_narrow()) {
   170         assert(UseCompressedOops, "Error");
   171         _oc->do_oop((narrowOop*)(*curr));
   172       } else {
   173         _oc->do_oop((oop*)(*curr));
   174       }
   175       ++hr_curr;
   176     }
   177     _buffer_curr = _buffer;
   178     _hr_curr = _hr_buffer;
   179     _closure_app_seconds += (os::elapsedTime() - start);
   180   }
   182 public:
   183   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
   184   virtual void do_oop(      oop* p) { do_oop_work(p); }
   186   template <class T> void do_oop_work(T* p) {
   187     if (_buffer_curr == _buffer_top) {
   188       assert(_hr_curr > _hr_buffer, "_hr_curr should be consistent with _buffer_curr");
   189       process_buffer();
   190     }
   191     StarTask new_ref(p);
   192     *_buffer_curr = new_ref;
   193     ++_buffer_curr;
   194     *_hr_curr = _from;
   195     ++_hr_curr;
   196   }
   197   void done () {
   198     if (_buffer_curr > _buffer) {
   199       assert(_hr_curr > _hr_buffer, "_hr_curr should be consistent with _buffer_curr");
   200       process_buffer();
   201     }
   202   }
   203   double closure_app_seconds () {
   204     return _closure_app_seconds;
   205   }
   206   BufferingOopsInHeapRegionClosure (OopsInHeapRegionClosure *oc) :
   207     _oc(oc),
   208     _buffer_curr(_buffer), _buffer_top(_buffer + BufferLength),
   209     _hr_curr(_hr_buffer),
   210     _closure_app_seconds(0.0) { }
   211 };
   213 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP

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