1 /*
2 * Copyright (c) 2019, 2020, Red Hat, Inc. 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
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeBehaviours.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/dependencyContext.hpp"
32 #include "gc/shared/gcBehaviours.hpp"
33 #include "gc/shared/suspendibleThreadSet.hpp"
34 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
35 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
36 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
37 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
38 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
39 #include "gc/shenandoah/shenandoahLock.hpp"
40 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
41 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
42 #include "gc/shenandoah/shenandoahUnload.hpp"
43 #include "gc/shenandoah/shenandoahVerifier.hpp"
44 #include "memory/iterator.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "oops/access.inline.hpp"
47
48 class ShenandoahIsUnloadingOopClosure : public OopClosure {
49 private:
50 ShenandoahMarkingContext* const _marking_context;
51 bool _is_unloading;
52
53 public:
54 ShenandoahIsUnloadingOopClosure() :
55 _marking_context(ShenandoahHeap::heap()->complete_marking_context()),
56 _is_unloading(false) {
57 }
58
59 virtual void do_oop(oop* p) {
60 if (_is_unloading) {
61 return;
62 }
63
64 const oop o = RawAccess<>::oop_load(p);
65 if (!CompressedOops::is_null(o) &&
66 !_marking_context->is_marked(o)) {
67 _is_unloading = true;
68 }
69 }
70
71 virtual void do_oop(narrowOop* p) {
72 ShouldNotReachHere();
73 }
74
75 bool is_unloading() const {
76 return _is_unloading;
77 }
78 };
79
80 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour {
81 public:
82 virtual bool is_unloading(CompiledMethod* method) const {
83 nmethod* const nm = method->as_nmethod();
84 assert(ShenandoahHeap::heap()->is_concurrent_weak_root_in_progress(), "Only for this phase");
85 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
86 ShenandoahReentrantLocker locker(data->lock());
87 ShenandoahIsUnloadingOopClosure cl;
88 data->oops_do(&cl);
89 return cl.is_unloading();
90 }
91 };
92
93 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
94 public:
95 virtual bool lock(CompiledMethod* method) {
96 nmethod* const nm = method->as_nmethod();
97 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
98 assert(lock != NULL, "Not yet registered?");
99 lock->lock();
100 return true;
101 }
102
103 virtual void unlock(CompiledMethod* method) {
104 nmethod* const nm = method->as_nmethod();
105 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
106 assert(lock != NULL, "Not yet registered?");
107 lock->unlock();
108 }
109
110 virtual bool is_safe(CompiledMethod* method) {
111 if (SafepointSynchronize::is_at_safepoint()) {
112 return true;
113 }
114
115 nmethod* const nm = method->as_nmethod();
116 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
117 assert(lock != NULL, "Not yet registered?");
118 return lock->owned_by_self();
119 }
120 };
121
122 ShenandoahUnload::ShenandoahUnload() {
123 if (ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
124 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
125 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
126
127 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
128 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
129 }
130 }
131
132 void ShenandoahUnload::prepare() {
133 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
134 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Sanity");
135 CodeCache::increment_unloading_cycle();
136 DependencyContext::cleaning_start();
137 }
138
139 class ShenandoahUnloadRendezvousClosure : public HandshakeClosure {
140 public:
141 ShenandoahUnloadRendezvousClosure() : HandshakeClosure("ShenandoahUnloadRendezvous") {}
142 void do_thread(Thread* thread) {}
143 };
144
145 void ShenandoahUnload::unload() {
146 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Why we here?");
147
148 ShenandoahHeap* heap = ShenandoahHeap::heap();
149
150 if (!heap->is_concurrent_weak_root_in_progress()) {
151 return;
152 }
153
154 // Unlink stale metadata and nmethods
155 {
156 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink);
157
158 SuspendibleThreadSetJoiner sts;
159 bool unloadingOccurred;
160 {
161 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_sd);
162 MutexLocker cldgMl(ClassLoaderDataGraph_lock);
163 unloadingOccurred = SystemDictionary::do_unloading(heap->gc_timer());
164 }
165
166 {
167 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_weak_klass);
168 Klass::clean_weak_klass_links(unloadingOccurred);
169 }
170
171 {
172 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_code_roots);
173 ShenandoahCodeRoots::unlink(heap->workers(), unloadingOccurred);
174 }
175
176 DependencyContext::cleaning_end();
177 }
178
179 // Make sure stale metadata and nmethods are no longer observable
180 {
181 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_rendezvous);
182 ShenandoahUnloadRendezvousClosure cl;
183 Handshake::execute(&cl);
184 }
185
186 // Purge stale metadata and nmethods that were unlinked
187 {
188 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge);
189
190 {
191 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_coderoots);
192 SuspendibleThreadSetJoiner sts;
193 ShenandoahCodeRoots::purge(heap->workers());
194 }
195
196 {
197 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_cldg);
198 ClassLoaderDataGraph::purge();
199 }
200
201 {
202 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_ec);
203 CodeCache::purge_exception_caches();
204 }
205 }
206 }
207
208 void ShenandoahUnload::finish() {
209 MetaspaceGC::compute_new_size();
210 MetaspaceUtils::verify_metrics();
211 }