1 /*
   2  * Copyright (c) 2015, 2016, 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 #include "precompiled.hpp"
  26 #include "gc/g1/g1OopClosures.inline.hpp"
  27 #include "gc/g1/g1RootClosures.hpp"
  28 #include "gc/g1/g1SharedClosures.hpp"
  29 
  30 // Closures used for standard G1 evacuation.
  31 class G1EvacuationClosures : public G1EvacuationRootClosures {
  32   G1SharedClosures<G1MarkNone> _closures;
  33 
  34 public:
  35   G1EvacuationClosures(G1CollectedHeap* g1h,
  36                        G1ParScanThreadState* pss,
  37                        bool gcs_are_young) :
  38       _closures(g1h, pss, gcs_are_young, /* must_claim_cld */ false) {}
  39 
  40   OopClosure* weak_oops()   { return &_closures._buffered_oops; }
  41   OopClosure* strong_oops() { return &_closures._buffered_oops; }
  42 
  43   CLDClosure* weak_clds()             { return &_closures._clds; }
  44   CLDClosure* strong_clds()           { return &_closures._clds; }
  45   CLDClosure* second_pass_weak_clds() { return NULL; }
  46 
  47   CodeBlobClosure* strong_codeblobs()      { return &_closures._codeblobs; }
  48   CodeBlobClosure* weak_codeblobs()        { return &_closures._codeblobs; }
  49 
  50   void flush()                 { _closures._buffered_oops.done(); }
  51   double closure_app_seconds() { return _closures._buffered_oops.closure_app_seconds(); }
  52 
  53   OopClosure* raw_strong_oops() { return &_closures._oops; }
  54 
  55   bool trace_metadata()         { return false; }
  56 };
  57 
  58 // Closures used during initial mark.
  59 // The treatment of "weak" roots is selectable through the template parameter,
  60 // this is usually used to control unloading of classes and interned strings.
  61 template <G1Mark MarkWeak>
  62 class G1InitalMarkClosures : public G1EvacuationRootClosures {
  63   G1SharedClosures<G1MarkFromRoot> _strong;
  64   G1SharedClosures<MarkWeak>       _weak;
  65 
  66   // Filter method to help with returning the appropriate closures
  67   // depending on the class template parameter.
  68   template <G1Mark Mark, typename T>
  69   T* null_if(T* t) {
  70     if (Mark == MarkWeak) {
  71       return NULL;
  72     }
  73     return t;
  74   }
  75 
  76 public:
  77   G1InitalMarkClosures(G1CollectedHeap* g1h,
  78                        G1ParScanThreadState* pss) :
  79       _strong(g1h, pss, /* process_only_dirty_klasses */ false, /* must_claim_cld */ true),
  80       _weak(g1h, pss,   /* process_only_dirty_klasses */ false, /* must_claim_cld */ true) {}
  81 
  82   OopClosure* weak_oops()   { return &_weak._buffered_oops; }
  83   OopClosure* strong_oops() { return &_strong._buffered_oops; }
  84 
  85   // If MarkWeak is G1MarkPromotedFromRoot then the weak CLDs must be processed in a second pass.
  86   CLDClosure* weak_clds()             { return null_if<G1MarkPromotedFromRoot>(&_weak._clds); }
  87   CLDClosure* strong_clds()           { return &_strong._clds; }
  88 
  89   // If MarkWeak is G1MarkFromRoot then all CLDs are processed by the weak and strong variants
  90   // return a NULL closure for the following specialized versions in that case.
  91   CLDClosure* second_pass_weak_clds() { return null_if<G1MarkFromRoot>(&_weak._clds); }
  92 
  93   CodeBlobClosure* strong_codeblobs()      { return &_strong._codeblobs; }
  94   CodeBlobClosure* weak_codeblobs()        { return &_weak._codeblobs; }
  95 
  96   void flush() {
  97     _strong._buffered_oops.done();
  98     _weak._buffered_oops.done();
  99   }
 100 
 101   double closure_app_seconds() {
 102     return _strong._buffered_oops.closure_app_seconds() +
 103            _weak._buffered_oops.closure_app_seconds();
 104   }
 105 
 106   OopClosure* raw_strong_oops() { return &_strong._oops; }
 107 
 108   // If we are not marking all weak roots then we are tracing
 109   // which metadata is alive.
 110   bool trace_metadata()         { return MarkWeak == G1MarkPromotedFromRoot; }
 111 };
 112 
 113 G1EvacuationRootClosures* G1EvacuationRootClosures::create_root_closures(G1ParScanThreadState* pss, G1CollectedHeap* g1h) {
 114   G1EvacuationRootClosures* res = create_root_closures_ext(pss, g1h);
 115   if (res != NULL) {
 116     return res;
 117   }
 118 
 119   if (g1h->collector_state()->during_initial_mark_pause()) {
 120     if (ClassUnloadingWithConcurrentMark) {
 121       res = new G1InitalMarkClosures<G1MarkPromotedFromRoot>(g1h, pss);
 122     } else {
 123       res = new G1InitalMarkClosures<G1MarkFromRoot>(g1h, pss);
 124     }
 125   } else {
 126     res = new G1EvacuationClosures(g1h, pss, g1h->collector_state()->gcs_are_young());
 127   }
 128   return res;
 129 }