1 /*
2 * Copyright (c) 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 #include "precompiled.hpp"
25 #include "classfile/classLoaderDataGraph.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "code/codeBehaviours.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/dependencyContext.hpp"
30 #include "gc/shared/gcBehaviours.hpp"
31 #include "gc/shared/suspendibleThreadSet.hpp"
32 #include "gc/z/zLock.inline.hpp"
33 #include "gc/z/zNMethodTable.hpp"
34 #include "gc/z/zOopClosures.hpp"
35 #include "gc/z/zStat.hpp"
36 #include "gc/z/zUnload.hpp"
37 #include "oops/access.inline.hpp"
38
39 static const ZStatSubPhase ZSubPhaseConcurrentClassesUnload("Concurrent Classes Unload");
40
41 class ZIsUnloadingOopClosure : public OopClosure {
42 private:
43 ZPhantomIsAliveObjectClosure _is_alive;
44 bool _is_unloading;
45
46 public:
47 ZIsUnloadingOopClosure() :
48 _is_alive(),
49 _is_unloading(false) {}
50
51 virtual void do_oop(oop* p) {
52 const oop o = RawAccess<>::oop_load(p);
53 if (o != NULL && !_is_alive.do_object_b(o)) {
54 _is_unloading = true;
55 }
56 }
57
58 virtual void do_oop(narrowOop* p) {
59 ShouldNotReachHere();
60 }
61
62 bool is_unloading() const {
63 return _is_unloading;
64 }
65 };
66
67 class ZIsUnloadingBehaviour : public IsUnloadingBehaviour {
68 private:
69 bool is_unloading(nmethod* nm) const {
70 ZIsUnloadingOopClosure cl;
71 nm->oops_do(&cl, true /* allow_zombie */);
72 return cl.is_unloading();
73 }
74
75 public:
76 virtual bool is_unloading(CompiledMethod* method) const {
77 nmethod* const nm = method->as_nmethod();
78 ZReentrantLock* const lock = ZNMethodTable::lock_for_nmethod(nm);
79 if (lock == NULL) {
80 return is_unloading(nm);
81 } else {
82 ZLocker<ZReentrantLock> locker(lock);
83 return is_unloading(nm);
84 }
85 }
86 };
87
88 class ZCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
89 public:
90 virtual bool lock(CompiledMethod* method) {
91 nmethod* const nm = method->as_nmethod();
92 ZReentrantLock* const lock = ZNMethodTable::lock_for_nmethod(nm);
93 if (lock != NULL) {
94 lock->lock();
95 }
96 return true;
97 }
98
99 virtual void unlock(CompiledMethod* method) {
100 nmethod* const nm = method->as_nmethod();
101 ZReentrantLock* const lock = ZNMethodTable::lock_for_nmethod(nm);
102 if (lock != NULL) {
103 lock->unlock();
104 }
105 }
106
107 virtual bool is_safe(CompiledMethod* method) {
108 if (SafepointSynchronize::is_at_safepoint()) {
109 return true;
110 }
111
112 nmethod* const nm = method->as_nmethod();
113 ZReentrantLock* const lock = ZNMethodTable::lock_for_nmethod(nm);
114 return lock == NULL || lock->is_owned();
115 }
116 };
117
118 ZUnload::ZUnload(ZWorkers* workers) :
119 _workers(workers) {
120
121 if (!ClassUnloading) {
122 return;
123 }
124
125 static ZIsUnloadingBehaviour is_unloading_behaviour;
126 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
127
128 static ZCompiledICProtectionBehaviour ic_protection_behaviour;
129 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
130 }
131
132 void ZUnload::prepare() {
133 if (!ClassUnloading) {
134 return;
135 }
136
137 CodeCache::increment_unloading_cycle();
138 DependencyContext::cleaning_start();
139 }
140
141 void ZUnload::unlink() {
142 SuspendibleThreadSetJoiner sts;
143 bool unloading_occurred;
144
145 {
146 MutexLockerEx ml(ClassLoaderDataGraph_lock);
147 unloading_occurred = SystemDictionary::do_unloading(ZStatPhase::timer());
148 }
149
150 Klass::clean_weak_klass_links(unloading_occurred);
151
152 ZNMethodTable::unlink(_workers, unloading_occurred);
153
154 DependencyContext::cleaning_end();
155 }
156
157 void ZUnload::purge() {
158 {
159 SuspendibleThreadSetJoiner sts;
160 ZNMethodTable::purge(_workers);
161 }
162
163 ClassLoaderDataGraph::purge();
164 CodeCache::purge_exception_caches();
165 }
166
167 class ZUnloadRendezvousClosure : public ThreadClosure {
168 public:
169 void do_thread(Thread* thread) {}
170 };
171
172 void ZUnload::unload() {
173 if (!ClassUnloading) {
174 return;
175 }
176
177 ZStatTimer timer(ZSubPhaseConcurrentClassesUnload);
178
179 // Unlink stale metadata and nmethods
180 unlink();
181
182 // Make sure stale metadata and nmethods are no longer observable
183 ZUnloadRendezvousClosure cl;
184 Handshake::execute(&cl);
185
186 // Purge stale metadata and nmethods that were unlinked
187 purge();
188 }
189
190 void ZUnload::finish() {
191 // Resize and verify metaspace
192 MetaspaceGC::compute_new_size();
193 MetaspaceUtils::verify_metrics();
194 }