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/shenandoahNMethod.inline.hpp"
38 #include "gc/shenandoah/shenandoahLock.hpp"
39 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
40 #include "gc/shenandoah/shenandoahUnload.hpp"
41 #include "gc/shenandoah/shenandoahVerifier.hpp"
42 #include "memory/iterator.hpp"
43 #include "memory/resourceArea.hpp"
44 #include "oops/access.inline.hpp"
45
46 class ShenandoahIsUnloadingOopClosure : public OopClosure {
47 private:
48 ShenandoahMarkingContext* const _marking_context;
49 bool _is_unloading;
50
51 public:
52 ShenandoahIsUnloadingOopClosure() :
53 _marking_context(ShenandoahHeap::heap()->complete_marking_context()),
54 _is_unloading(false) {
55 }
56
57 virtual void do_oop(oop* p) {
58 if (_is_unloading) {
59 return;
60 }
61
62 const oop o = RawAccess<>::oop_load(p);
63 if (!CompressedOops::is_null(o) &&
64 !_marking_context->is_marked(o)) {
65 _is_unloading = true;
66 }
67 }
68
69 virtual void do_oop(narrowOop* p) {
70 ShouldNotReachHere();
71 }
72
73 bool is_unloading() const {
74 return _is_unloading;
75 }
76 };
77
78 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour {
79 public:
80 virtual bool is_unloading(CompiledMethod* method) const {
81 ShenandoahHeap* const heap = ShenandoahHeap::heap();
82 nmethod* const nm = method->as_nmethod();
83
84 if (heap->is_concurrent_mark_in_progress()) {
85 ShenandoahNMethod::keep_metadata_alive(nm);
86 return false;
87 }
88 assert(heap->is_concurrent_root_in_progress(), "What else?");
89 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
90 ShenandoahReentrantLocker locker(data->lock());
91 ShenandoahIsUnloadingOopClosure cl;
92 data->oops_do(&cl);
93 return cl.is_unloading();
94 }
95 };
96
97 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
98 public:
99 virtual bool lock(CompiledMethod* method) {
100 nmethod* const nm = method->as_nmethod();
101 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
102 assert(lock != NULL, "Not yet registered?");
103 lock->lock();
104 return true;
105 }
106
107 virtual void unlock(CompiledMethod* method) {
108 nmethod* const nm = method->as_nmethod();
109 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
110 assert(lock != NULL, "Not yet registered?");
111 lock->unlock();
112 }
113
114 virtual bool is_safe(CompiledMethod* method) {
115 if (SafepointSynchronize::is_at_safepoint()) {
116 return true;
117 }
118
119 nmethod* const nm = method->as_nmethod();
120 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
121 assert(lock != NULL, "Not yet registered?");
122 return lock->owned_by_self();
123 }
124 };
125
126 ShenandoahUnload::ShenandoahUnload() {
127 if (ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
128 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
129 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
130
131 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
132 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
133 }
134 }
135
136 void ShenandoahUnload::prepare() {
137 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
138 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Sanity");
139 CodeCache::increment_unloading_cycle();
140 DependencyContext::cleaning_start();
141 }
142
143 void ShenandoahUnload::unlink() {
144 SuspendibleThreadSetJoiner sts;
145 bool unloading_occurred;
146 ShenandoahHeap* const heap = ShenandoahHeap::heap();
147 {
148 MutexLocker cldg_ml(ClassLoaderDataGraph_lock);
149 unloading_occurred = SystemDictionary::do_unloading(heap->gc_timer());
150 }
151
152 Klass::clean_weak_klass_links(unloading_occurred);
153 ShenandoahCodeRoots::unlink(ShenandoahHeap::heap()->workers(), unloading_occurred);
154 DependencyContext::cleaning_end();
155 }
156
157 void ShenandoahUnload::purge() {
158 {
159 SuspendibleThreadSetJoiner sts;
160 ShenandoahCodeRoots::purge(ShenandoahHeap::heap()->workers());
161 }
162
163 ClassLoaderDataGraph::purge();
164 CodeCache::purge_exception_caches();
165 }
166
167 class ShenandoahUnloadRendezvousClosure : public HandshakeClosure {
168 public:
169 ShenandoahUnloadRendezvousClosure() : HandshakeClosure("ShenandoahUnloadRendezvous") {}
170 void do_thread(Thread* thread) {}
171 };
172
173 void ShenandoahUnload::unload() {
174 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Why we here?");
175 if (!ShenandoahHeap::heap()->is_concurrent_root_in_progress()) {
176 return;
177 }
178
179 // Unlink stale metadata and nmethods
180 unlink();
181
182 // Make sure stale metadata and nmethods are no longer observable
183 ShenandoahUnloadRendezvousClosure cl;
184 Handshake::execute(&cl);
185
186 // Purge stale metadata and nmethods that were unlinked
187 purge();
188 }
189
190 void ShenandoahUnload::finish() {
191 MetaspaceGC::compute_new_size();
192 MetaspaceUtils::verify_metrics();
193 }