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.
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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
37 // A G1RemSet in which each heap region has a rem set that records the
38 // external heap references into it. Uses a mod ref bs to track updates,
39 // so that they can be used to update the individual region remsets.
40
41 class G1RemSet: public CHeapObj<mtGC> {
42 private:
43 G1RemSetSummary _prev_period_summary;
44
45 // A DirtyCardQueueSet that is used to hold cards that contain
46 // references into the current collection set. This is used to
47 // update the remembered sets of the regions in the collection
48 // set in the event of an evacuation failure.
49 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
50
51 protected:
52 G1CollectedHeap* _g1;
53 size_t _conc_refine_cards;
54 uint n_workers();
55
56 protected:
57 CardTableModRefBS* _ct_bs;
58 G1CollectorPolicy* _g1p;
59
60 ConcurrentG1Refine* _cg1r;
61
62 // Used for caching the closure that is responsible for scanning
63 // references into the collection set.
64 G1ParPushHeapRSClosure** _cset_rs_update_cl;
65
66 // Print the given summary info
67 virtual void print_summary_info(G1RemSetSummary * summary, const char * header = NULL);
68 public:
69 // This is called to reset dual hash tables after the gc pause
70 // is finished and the initial hash table is no longer being
71 // scanned.
72 void cleanupHRRS();
73
74 G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
75 ~G1RemSet();
76
77 // Invoke "blk->do_oop" on all pointers into the collection set
78 // from objects in regions outside the collection set (having
79 // invoked "blk->set_region" to set the "from" region correctly
80 // beforehand.)
81 //
82 // Apply non_heap_roots on the oops of the unmarked nmethods
83 // on the strong code roots list for each region in the
84 // collection set.
85 //
86 // The "worker_i" param is for the parallel case where the id
87 // of the worker thread calling this function can be helpful in
88 // partitioning the work to be done. It should be the same as
89 // the "i" passed to the calling thread's work(i) function.
90 // In the sequential case this param will be ignored.
91 //
92 // Returns the number of cards scanned while looking for pointers
93 // into the collection set.
94 size_t oops_into_collection_set_do(G1ParPushHeapRSClosure* blk,
95 CodeBlobClosure* heap_region_codeblobs,
96 uint worker_i);
97
98 // Prepare for and cleanup after an oops_into_collection_set_do
99 // call. Must call each of these once before and after (in sequential
100 // code) any threads call oops_into_collection_set_do. (This offers an
101 // opportunity to sequential setup and teardown of structures needed by a
102 // parallel iteration over the CS's RS.)
103 void prepare_for_oops_into_collection_set_do();
104 void cleanup_after_oops_into_collection_set_do();
105
106 size_t scanRS(G1ParPushHeapRSClosure* oc,
107 CodeBlobClosure* heap_region_codeblobs,
108 uint worker_i);
109
110 void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);
111
112 CardTableModRefBS* ct_bs() { return _ct_bs; }
113
114 // Record, if necessary, the fact that *p (where "p" is in region "from",
115 // which is required to be non-NULL) has changed to a new non-NULL value.
116 template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
117
118 // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
119 // or card, respectively, such that a region or card with a corresponding
120 // 0 bit contains no part of any live object. Eliminates any remembered
121 // set entries that correspond to dead heap ranges. "worker_num" is the
122 // parallel thread id of the current thread, and "hrclaimer" is the
123 // HeapRegionClaimer that should be used.
124 void scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer* hrclaimer);
125
126 // Refine the card corresponding to "card_ptr".
127 // If check_for_refs_into_cset is true, a true result is returned
128 // if the given card contains oops that have references into the
129 // current collection set.
130 virtual bool refine_card(jbyte* card_ptr,
131 uint worker_i,
132 bool check_for_refs_into_cset);
133
134 // Print accumulated summary info from the start of the VM.
135 virtual void print_summary_info();
136
137 // Print accumulated summary info from the last time called.
138 virtual void print_periodic_summary_info(const char* header);
139
140 // Prepare remembered set for verification.
141 virtual void prepare_for_verify();
142
143 size_t conc_refine_cards() const {
144 return _conc_refine_cards;
145 }
146 };
147
148 class ScanRSClosure : public HeapRegionClosure {
149 size_t _cards_done, _cards;
150 G1CollectedHeap* _g1h;
151
152 G1ParPushHeapRSClosure* _oc;
153 CodeBlobClosure* _code_root_cl;
154
155 G1BlockOffsetSharedArray* _bot_shared;
156 G1SATBCardTableModRefBS *_ct_bs;
157
158 double _strong_code_root_scan_time_sec;
159 uint _worker_i;
160 size_t _block_size;
161 bool _try_claimed;
162
163 public:
164 ScanRSClosure(G1ParPushHeapRSClosure* oc,
165 CodeBlobClosure* code_root_cl,
166 uint worker_i);
167
168 bool doHeapRegion(HeapRegion* r);
169
170 double strong_code_root_scan_time_sec() {
171 return _strong_code_root_scan_time_sec;
172 }
173 size_t cards_done() { return _cards_done;}
174 size_t cards_looked_up() { return _cards;}
175 void set_try_claimed() { _try_claimed = true; }
176 private:
177 void scanCard(size_t index, HeapRegion *r);
178 void printCard(HeapRegion* card_region, size_t card_index,
179 HeapWord* card_start);
180 void scan_strong_code_roots(HeapRegion* r);
181 };
182
183 class UpdateRSOopClosure: public ExtendedOopClosure {
184 HeapRegion* _from;
185 G1RemSet* _rs;
186 uint _worker_i;
187
188 template <class T> void do_oop_work(T* p);
189
190 public:
191 UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
192 _from(NULL), _rs(rs), _worker_i(worker_i)
193 {}
194
195 void set_from(HeapRegion* from) {
196 assert(from != NULL, "from region must be non-NULL");
197 _from = from;
198 }
199
200 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
201 virtual void do_oop(oop* p) { do_oop_work(p); }
202
203 // Override: this closure is idempotent.
204 // bool idempotent() { return true; }
205 bool apply_to_weak_ref_discovered_field() { return true; }
206 };
207
208 #endif // SHARE_VM_GC_G1_G1REMSET_HPP