1 /*
2 * Copyright (c) 2011, 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_implementation/g1/heapRegionRemSet.hpp"
27 #include "gc_implementation/g1/heapRegionSets.hpp"
28
29 // Note on the check_mt_safety() methods below:
30 //
31 // Verification of the "master" heap region sets / lists that are
32 // maintained by G1CollectedHeap is always done during a STW pause and
33 // by the VM thread at the start / end of the pause. The standard
34 // verification methods all assert check_mt_safety(). This is
35 // important as it ensures that verification is done without
36 // concurrent updates taking place at the same time. It follows, that,
37 // for the "master" heap region sets / lists, the check_mt_safety()
38 // method should include the VM thread / STW case.
39
40 //////////////////// FreeRegionList ////////////////////
41
42 const char* FreeRegionList::verify_region_extra(HeapRegion* hr) {
43 if (hr->is_young()) {
44 return "the region should not be young";
45 }
46 // The superclass will check that the region is empty and
47 // not humongous.
48 return HeapRegionLinkedList::verify_region_extra(hr);
49 }
50
51 //////////////////// MasterFreeRegionList ////////////////////
52
53 const char* MasterFreeRegionList::verify_region_extra(HeapRegion* hr) {
54 // We should reset the RSet for parallel iteration before we add it
55 // to the master free list so that it is ready when the region is
56 // re-allocated.
57 if (!hr->rem_set()->verify_ready_for_par_iteration()) {
58 return "the region's RSet should be ready for parallel iteration";
59 }
60 return FreeRegionList::verify_region_extra(hr);
61 }
62
63 bool MasterFreeRegionList::check_mt_safety() {
64 // Master Free List MT safety protocol:
65 // (a) If we're at a safepoint, operations on the master free list
66 // should be invoked by either the VM thread (which will serialize
67 // them) or by the GC workers while holding the
68 // FreeList_lock.
69 // (b) If we're not at a safepoint, operations on the master free
70 // list should be invoked while holding the Heap_lock.
71
72 if (SafepointSynchronize::is_at_safepoint()) {
73 guarantee(Thread::current()->is_VM_thread() ||
74 FreeList_lock->owned_by_self(),
75 hrs_ext_msg(this, "master free list MT safety protocol "
76 "at a safepoint"));
77 } else {
78 guarantee(Heap_lock->owned_by_self(),
79 hrs_ext_msg(this, "master free list MT safety protocol "
80 "outside a safepoint"));
81 }
82
83 return FreeRegionList::check_mt_safety();
84 }
85
86 //////////////////// SecondaryFreeRegionList ////////////////////
87
88 bool SecondaryFreeRegionList::check_mt_safety() {
89 // Secondary Free List MT safety protocol:
90 // Operations on the secondary free list should always be invoked
91 // while holding the SecondaryFreeList_lock.
92
93 guarantee(SecondaryFreeList_lock->owned_by_self(),
94 hrs_ext_msg(this, "secondary free list MT safety protocol"));
95
96 return FreeRegionList::check_mt_safety();
97 }
98
99 //////////////////// OldRegionSet ////////////////////
100
101 const char* OldRegionSet::verify_region_extra(HeapRegion* hr) {
102 if (hr->is_young()) {
103 return "the region should not be young";
104 }
105 // The superclass will check that the region is not empty and not
106 // humongous.
107 return HeapRegionSet::verify_region_extra(hr);
108 }
109
110 //////////////////// MasterOldRegionSet ////////////////////
111
112 bool MasterOldRegionSet::check_mt_safety() {
113 // Master Old Set MT safety protocol:
114 // (a) If we're at a safepoint, operations on the master old set
115 // should be invoked:
116 // - by the VM thread (which will serialize them), or
117 // - by the GC workers while holding the FreeList_lock, if we're
118 // at a safepoint for an evacuation pause (this lock is taken
119 // anyway when an GC alloc region is retired so that a new one
120 // is allocated from the free list), or
121 // - by the GC workers while holding the OldSets_lock, if we're at a
122 // safepoint for a cleanup pause.
123 // (b) If we're not at a safepoint, operations on the master old set
124 // should be invoked while holding the Heap_lock.
125
126 if (SafepointSynchronize::is_at_safepoint()) {
127 guarantee(Thread::current()->is_VM_thread() ||
128 _phase == HRSPhaseEvacuation && FreeList_lock->owned_by_self() ||
129 _phase == HRSPhaseCleanup && OldSets_lock->owned_by_self(),
130 hrs_ext_msg(this, "master old set MT safety protocol "
131 "at a safepoint"));
132 } else {
133 guarantee(Heap_lock->owned_by_self(),
134 hrs_ext_msg(this, "master old set MT safety protocol "
135 "outside a safepoint"));
136 }
137
138 return OldRegionSet::check_mt_safety();
139 }
140
141 //////////////////// HumongousRegionSet ////////////////////
142
143 const char* HumongousRegionSet::verify_region_extra(HeapRegion* hr) {
144 if (hr->is_young()) {
145 return "the region should not be young";
146 }
147 // The superclass will check that the region is not empty and
148 // humongous.
149 return HeapRegionSet::verify_region_extra(hr);
150 }
151
152 //////////////////// MasterHumongousRegionSet ////////////////////
153
154 bool MasterHumongousRegionSet::check_mt_safety() {
155 // Master Humongous Set MT safety protocol:
156 // (a) If we're at a safepoint, operations on the master humongous
157 // set should be invoked by either the VM thread (which will
158 // serialize them) or by the GC workers while holding the
159 // OldSets_lock.
160 // (b) If we're not at a safepoint, operations on the master
161 // humongous set should be invoked while holding the Heap_lock.
162
163 if (SafepointSynchronize::is_at_safepoint()) {
164 guarantee(Thread::current()->is_VM_thread() ||
165 OldSets_lock->owned_by_self(),
166 hrs_ext_msg(this, "master humongous set MT safety protocol "
167 "at a safepoint"));
168 } else {
169 guarantee(Heap_lock->owned_by_self(),
170 hrs_ext_msg(this, "master humongous set MT safety protocol "
171 "outside a safepoint"));
172 }
173
174 return HumongousRegionSet::check_mt_safety();
175 }