1 /*
  2  * Copyright (c) 2015, 2018, 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 in_young_gc) :
 38       _closures(g1h, pss, in_young_gc, /* cld_claim_value */ ClassLoaderData::_claim_value_none) {}
 39 
 40   OopClosure* weak_oops()   { return &_closures._oops; }
 41   OopClosure* strong_oops() { return &_closures._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   OopClosure* raw_strong_oops() { return &_closures._oops; }
 51 
 52   bool trace_metadata()         { return false; }
 53 };
 54 
 55 // Closures used during initial mark.
 56 // The treatment of "weak" roots is selectable through the template parameter,
 57 // this is usually used to control unloading of classes and interned strings.
 58 template <G1Mark MarkWeak>
 59 class G1InitialMarkClosures : public G1EvacuationRootClosures {
 60   G1SharedClosures<G1MarkFromRoot> _strong;
 61   G1SharedClosures<MarkWeak>       _weak;
 62 
 63   // Filter method to help with returning the appropriate closures
 64   // depending on the class template parameter.
 65   template <G1Mark Mark, typename T>
 66   T* null_if(T* t) {
 67     if (Mark == MarkWeak) {
 68       return NULL;
 69     }
 70     return t;
 71   }
 72 
 73 public:
 74   G1InitialMarkClosures(G1CollectedHeap* g1h,
 75                         G1ParScanThreadState* pss) :
 76       _strong(g1h, pss, /* process_only_dirty_klasses */ false, /* cld_claim_value */ ClassLoaderData::_claim_value_strong),
 77       _weak(g1h, pss,   /* process_only_dirty_klasses */ false, /* cld_claim_value */ ClassLoaderData::_claim_value_strong) {}
 78 
 79   OopClosure* weak_oops()   { return &_weak._oops; }
 80   OopClosure* strong_oops() { return &_strong._oops; }
 81 
 82   // If MarkWeak is G1MarkPromotedFromRoot then the weak CLDs must be processed in a second pass.
 83   CLDClosure* weak_clds()             { return null_if<G1MarkPromotedFromRoot>(&_weak._clds); }
 84   CLDClosure* strong_clds()           { return &_strong._clds; }
 85 
 86   // If MarkWeak is G1MarkFromRoot then all CLDs are processed by the weak and strong variants
 87   // return a NULL closure for the following specialized versions in that case.
 88   CLDClosure* second_pass_weak_clds() { return null_if<G1MarkFromRoot>(&_weak._clds); }
 89 
 90   CodeBlobClosure* strong_codeblobs()      { return &_strong._codeblobs; }
 91   CodeBlobClosure* weak_codeblobs()        { return &_weak._codeblobs; }
 92 
 93   OopClosure* raw_strong_oops() { return &_strong._oops; }
 94 
 95   // If we are not marking all weak roots then we are tracing
 96   // which metadata is alive.
 97   bool trace_metadata()         { return MarkWeak == G1MarkPromotedFromRoot; }
 98 };
 99 
100 G1EvacuationRootClosures* G1EvacuationRootClosures::create_root_closures(G1ParScanThreadState* pss, G1CollectedHeap* g1h) {
101   G1EvacuationRootClosures* res = NULL;
102   if (g1h->collector_state()->in_initial_mark_gc()) {
103     if (ClassUnloadingWithConcurrentMark) {
104       res = new G1InitialMarkClosures<G1MarkPromotedFromRoot>(g1h, pss);
105     } else {
106       res = new G1InitialMarkClosures<G1MarkFromRoot>(g1h, pss);
107     }
108   } else {
109     res = new G1EvacuationClosures(g1h, pss, g1h->collector_state()->in_young_only_phase());
110   }
111   return res;
112 }