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/heapRegionSet.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 void FreeRegionList::verify_list() {
43 HeapRegion* curr = head();
44 HeapRegion* prev1 = NULL;
45 HeapRegion* prev0 = NULL;
46 uint count = 0;
47 size_t capacity = 0;
48 while (curr != NULL) {
49 verify_region(curr);
50
51 count++;
52 guarantee(count < _unrealistically_long_length,
53 hrs_err_msg("[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: "PTR_FORMAT" prev0: "PTR_FORMAT" " "prev1: "PTR_FORMAT" length: %u", name(), count, curr, prev0, prev1, length()));
54
55 capacity += curr->capacity();
56
57 prev1 = prev0;
58 prev0 = curr;
59 curr = curr->next();
60 }
61
62 guarantee(tail() == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), tail()->hrs_index(), prev0->hrs_index()));
63
64 guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));
65 guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
66 name(), total_capacity_bytes(), capacity));
67 }
68
69 //////////////////// MasterFreeRegionList ////////////////////
70
71 bool MasterFreeRegionListMtSafeChecker::check() {
72 // Master Free List MT safety protocol:
73 // (a) If we're at a safepoint, operations on the master free list
74 // should be invoked by either the VM thread (which will serialize
75 // them) or by the GC workers while holding the
76 // FreeList_lock.
77 // (b) If we're not at a safepoint, operations on the master free
78 // list should be invoked while holding the Heap_lock.
79
80 if (SafepointSynchronize::is_at_safepoint()) {
81 guarantee(Thread::current()->is_VM_thread() ||
82 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
83 } else {
84 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
85 }
86
87 return true;
88 }
89
90 //////////////////// SecondaryFreeRegionList ////////////////////
91
92 bool SecondaryFreeRegionListMtSafeChecker::check() {
93 // Secondary Free List MT safety protocol:
94 // Operations on the secondary free list should always be invoked
95 // while holding the SecondaryFreeList_lock.
96
97 guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol");
98
99 return true;
100 }
101
102 //////////////////// OldRegionSet ////////////////////
103
104 bool OldRegionSetMtSafeChecker::check() {
105 // Master Old Set MT safety protocol:
106 // (a) If we're at a safepoint, operations on the master old set
107 // should be invoked:
108 // - by the VM thread (which will serialize them), or
109 // - by the GC workers while holding the FreeList_lock, if we're
110 // at a safepoint for an evacuation pause (this lock is taken
111 // anyway when an GC alloc region is retired so that a new one
112 // is allocated from the free list), or
113 // - by the GC workers while holding the OldSets_lock, if we're at a
114 // safepoint for a cleanup pause.
115 // (b) If we're not at a safepoint, operations on the master old set
116 // should be invoked while holding the Heap_lock.
117
118 if (SafepointSynchronize::is_at_safepoint()) {
119 guarantee(Thread::current()->is_VM_thread()
120 || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
121 "master old set MT safety protocol at a safepoint");
122 } else {
123 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
124 }
125
126 return true;
127 }
128
129 //////////////////// HumongousRegionSet ////////////////////
130
131 bool HumongousRegionSetMtSafeChecker::check() {
132 // Humongous Set MT safety protocol:
133 // (a) If we're at a safepoint, operations on the master humongous
134 // set should be invoked by either the VM thread (which will
135 // serialize them) or by the GC workers while holding the
136 // OldSets_lock.
137 // (b) If we're not at a safepoint, operations on the master
138 // humongous set should be invoked while holding the Heap_lock.
139
140 if (SafepointSynchronize::is_at_safepoint()) {
141 guarantee(Thread::current()->is_VM_thread() ||
142 OldSets_lock->owned_by_self(),
143 "master humongous set MT safety protocol at a safepoint");
144 } else {
145 guarantee(Heap_lock->owned_by_self(),
146 "master humongous set MT safety protocol outside a safepoint");
147 }
148
149 return true;
150 }