1 /*
2 * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeBehaviours.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/dependencyContext.hpp"
31 #include "gc/shared/gcBehaviours.hpp"
32 #include "gc/shared/suspendibleThreadSet.hpp"
33 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
34 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
35 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
36 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
37 #include "gc/shenandoah/shenandoahLock.hpp"
38 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
39 #include "gc/shenandoah/shenandoahUnload.hpp"
40 #include "gc/shenandoah/shenandoahVerifier.hpp"
41 #include "memory/iterator.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "oops/access.inline.hpp"
44
45 class ShenandoahIsUnloadingOopClosure : public OopClosure {
46 private:
47 ShenandoahMarkingContext* _marking_context;
48 bool _is_unloading;
49
50 public:
51 ShenandoahIsUnloadingOopClosure() :
52 _marking_context(ShenandoahHeap::heap()->marking_context()),
53 _is_unloading(false) {
54 }
55
56 virtual void do_oop(oop* p) {
57 if (_is_unloading) {
58 return;
59 }
60
61 const oop o = RawAccess<>::oop_load(p);
62 if (!CompressedOops::is_null(o) &&
63 _marking_context->is_complete() &&
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 nmethod* const nm = method->as_nmethod();
82 guarantee(ShenandoahHeap::heap()->is_evacuation_in_progress(), "Only this phase");
83 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
84 ShenandoahReentrantLocker locker(data->lock());
85 ShenandoahIsUnloadingOopClosure cl;
86 data->oops_do(&cl);
87 return cl.is_unloading();
88 }
89 };
90
91 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
92 public:
93 virtual bool lock(CompiledMethod* method) {
94 nmethod* const nm = method->as_nmethod();
95 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
96 assert(lock != NULL, "Not yet registered?");
97 lock->lock();
98 return true;
99 }
100
101 virtual void unlock(CompiledMethod* method) {
102 nmethod* const nm = method->as_nmethod();
103 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
104 assert(lock != NULL, "Not yet registered?");
105 lock->unlock();
106 }
107
108 virtual bool is_safe(CompiledMethod* method) {
109 if (SafepointSynchronize::is_at_safepoint()) {
110 return true;
111 }
112
113 nmethod* const nm = method->as_nmethod();
114 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
115 assert(lock != NULL, "Not yet registered?");
116 return lock->owned_by_self();
117 }
118 };
119
120 ShenandoahUnload::ShenandoahUnload() {
121 if (ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
122 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
123 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
124
125 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
126 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
127 }
128 }
129
130 void ShenandoahUnload::prepare() {
131 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
132 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Sanity");
133 CodeCache::increment_unloading_cycle();
134 DependencyContext::cleaning_start();
135 }
136
137 void ShenandoahUnload::unlink() {
138 SuspendibleThreadSetJoiner sts;
139 bool unloading_occurred;
140 ShenandoahHeap* const heap = ShenandoahHeap::heap();
141 {
142 MutexLocker cldg_ml(ClassLoaderDataGraph_lock);
143 unloading_occurred = SystemDictionary::do_unloading(heap->gc_timer());
144 }
145
146 Klass::clean_weak_klass_links(unloading_occurred);
147 ShenandoahCodeRoots::unlink(ShenandoahHeap::heap()->workers(), unloading_occurred);
148 DependencyContext::cleaning_end();
149 }
150
151 void ShenandoahUnload::purge() {
152 {
153 SuspendibleThreadSetJoiner sts;
154 ShenandoahCodeRoots::purge(ShenandoahHeap::heap()->workers());
155 }
156
157 ClassLoaderDataGraph::purge();
158 CodeCache::purge_exception_caches();
159 }
160
161 class ShenandoahUnloadRendezvousClosure : public HandshakeClosure {
162 public:
163 ShenandoahUnloadRendezvousClosure() : HandshakeClosure("ShenandoahUnloadRendezvous") {}
164 void do_thread(Thread* thread) {}
165 };
166
167 void ShenandoahUnload::unload() {
168 assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(), "Why we here?");
169 if (!ShenandoahHeap::heap()->is_evacuation_in_progress()) {
170 return;
171 }
172
173 // Unlink stale metadata and nmethods
174 unlink();
175
176 // Make sure stale metadata and nmethods are no longer observable
177 ShenandoahUnloadRendezvousClosure cl;
178 Handshake::execute(&cl);
179
180 // Purge stale metadata and nmethods that were unlinked
181 purge();
182 }
183
184 void ShenandoahUnload::finish() {
185 MetaspaceGC::compute_new_size();
186 MetaspaceUtils::verify_metrics();
187 }