1 /*
2 * Copyright (c) 2001, 2015, 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
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1REMSET_HPP
26 #define SHARE_VM_GC_G1_G1REMSET_HPP
27
28 #include "gc/g1/g1RemSetSummary.hpp"
29
30 // A G1RemSet provides ways of iterating over pointers into a selected
31 // collection set.
32
33 class G1CollectedHeap;
34 class ConcurrentG1Refine;
35 class G1ParPushHeapRSClosure;
36 class outputStream;
37
38 // A G1RemSet in which each heap region has a rem set that records the
39 // external heap references into it. Uses a mod ref bs to track updates,
40 // so that they can be used to update the individual region remsets.
41
42 class G1RemSet: public CHeapObj<mtGC> {
43 private:
44 G1RemSetSummary _prev_period_summary;
45 protected:
46 G1CollectedHeap* _g1;
47 size_t _conc_refine_cards;
48 uint n_workers();
49
50 protected:
51 enum SomePrivateConstants {
52 UpdateRStoMergeSync = 0,
53 MergeRStoDoDirtySync = 1,
54 DoDirtySync = 2,
55 LastSync = 3,
56
57 SeqTask = 0,
58 NumSeqTasks = 1
59 };
60
61 CardTableModRefBS* _ct_bs;
62 G1CollectorPolicy* _g1p;
63
64 ConcurrentG1Refine* _cg1r;
65
66 // Used for caching the closure that is responsible for scanning
67 // references into the collection set.
68 G1ParPushHeapRSClosure** _cset_rs_update_cl;
69
70 public:
71 // This is called to reset dual hash tables after the gc pause
72 // is finished and the initial hash table is no longer being
73 // scanned.
74 void cleanupHRRS();
75
76 G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
77 ~G1RemSet();
78
79 // Invoke "blk->do_oop" on all pointers into the collection set
80 // from objects in regions outside the collection set (having
81 // invoked "blk->set_region" to set the "from" region correctly
82 // beforehand.)
83 //
84 // Apply non_heap_roots on the oops of the unmarked nmethods
85 // on the strong code roots list for each region in the
86 // collection set.
87 //
88 // The "worker_i" param is for the parallel case where the id
89 // of the worker thread calling this function can be helpful in
90 // partitioning the work to be done. It should be the same as
91 // the "i" passed to the calling thread's work(i) function.
92 // In the sequential case this param will be ignored.
93 //
94 // Returns the number of cards scanned while looking for pointers
95 // into the collection set.
96 size_t oops_into_collection_set_do(G1ParPushHeapRSClosure* blk,
97 CodeBlobClosure* heap_region_codeblobs,
98 uint worker_i);
99
100 // Prepare for and cleanup after an oops_into_collection_set_do
101 // call. Must call each of these once before and after (in sequential
102 // code) any threads call oops_into_collection_set_do. (This offers an
103 // opportunity to sequential setup and teardown of structures needed by a
104 // parallel iteration over the CS's RS.)
105 void prepare_for_oops_into_collection_set_do();
106 void cleanup_after_oops_into_collection_set_do();
107
108 size_t scanRS(G1ParPushHeapRSClosure* oc,
109 CodeBlobClosure* heap_region_codeblobs,
110 uint worker_i);
111
112 void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);
113
114 CardTableModRefBS* ct_bs() { return _ct_bs; }
115
116 // Record, if necessary, the fact that *p (where "p" is in region "from",
117 // which is required to be non-NULL) has changed to a new non-NULL value.
118 template <class T> void write_ref(HeapRegion* from, T* p);
119 template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
120
121 // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
122 // or card, respectively, such that a region or card with a corresponding
123 // 0 bit contains no part of any live object. Eliminates any remembered
124 // set entries that correspond to dead heap ranges. "worker_num" is the
125 // parallel thread id of the current thread, and "hrclaimer" is the
126 // HeapRegionClaimer that should be used.
127 void scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer* hrclaimer);
128
129 // Refine the card corresponding to "card_ptr".
130 // If check_for_refs_into_cset is true, a true result is returned
131 // if the given card contains oops that have references into the
132 // current collection set.
133 virtual bool refine_card(jbyte* card_ptr,
134 uint worker_i,
135 bool check_for_refs_into_cset);
136
137 // Print accumulated summary info from the start of the VM.
138 virtual void print_summary_info();
139
140 // Print accumulated summary info from the last time called.
141 virtual void print_periodic_summary_info(const char* header, uint period_count);
142
143 // Prepare remembered set for verification.
144 virtual void prepare_for_verify();
145
146 size_t conc_refine_cards() const {
147 return _conc_refine_cards;
148 }
149 };
150
151 class UpdateRSOopClosure: public ExtendedOopClosure {
152 HeapRegion* _from;
153 G1RemSet* _rs;
154 uint _worker_i;
155
156 template <class T> void do_oop_work(T* p);
157
158 public:
159 UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
160 _from(NULL), _rs(rs), _worker_i(worker_i)
161 {}
162
163 void set_from(HeapRegion* from) {
164 assert(from != NULL, "from region must be non-NULL");
165 _from = from;
166 }
167
168 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
169 virtual void do_oop(oop* p) { do_oop_work(p); }
170
171 // Override: this closure is idempotent.
172 // bool idempotent() { return true; }
173 bool apply_to_weak_ref_discovered_field() { return true; }
174 };
175
176 #endif // SHARE_VM_GC_G1_G1REMSET_HPP