1 /*
   2  * Copyright (c) 2018, 2019, 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/zNMethod.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 ZSubPhaseConcurrentClassesUnlink("Concurrent Classes Unlink");
  40 static const ZStatSubPhase ZSubPhaseConcurrentClassesPurge("Concurrent Classes Purge");
  41 
  42 class ZIsUnloadingOopClosure : public OopClosure {
  43 private:
  44   ZPhantomIsAliveObjectClosure _is_alive;
  45   bool                         _is_unloading;
  46 
  47 public:
  48   ZIsUnloadingOopClosure() :
  49       _is_alive(),
  50       _is_unloading(false) {}
  51 
  52   virtual void do_oop(oop* p) {
  53     const oop o = RawAccess<>::oop_load(p);
  54     if (o != NULL && !_is_alive.do_object_b(o)) {
  55       _is_unloading = true;
  56     }
  57   }
  58 
  59   virtual void do_oop(narrowOop* p) {
  60     ShouldNotReachHere();
  61   }
  62 
  63   bool is_unloading() const {
  64     return _is_unloading;
  65   }
  66 };
  67 
  68 class ZIsUnloadingBehaviour : public IsUnloadingBehaviour {
  69 public:
  70   virtual bool is_unloading(CompiledMethod* method) const {
  71     nmethod* const nm = method->as_nmethod();
  72     ZReentrantLock* const lock = ZNMethod::lock_for_nmethod(nm);
  73     ZLocker<ZReentrantLock> locker(lock);
  74     ZIsUnloadingOopClosure cl;
  75     ZNMethod::nmethod_oops_do(nm, &cl);
  76     return cl.is_unloading();
  77   }
  78 };
  79 
  80 class ZCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
  81 public:
  82   virtual bool lock(CompiledMethod* method) {
  83     nmethod* const nm = method->as_nmethod();
  84     ZReentrantLock* const lock = ZNMethod::lock_for_nmethod(nm);
  85     lock->lock();
  86     return true;
  87   }
  88 
  89   virtual void unlock(CompiledMethod* method) {
  90     nmethod* const nm = method->as_nmethod();
  91     ZReentrantLock* const lock = ZNMethod::lock_for_nmethod(nm);
  92     lock->unlock();
  93   }
  94 
  95   virtual bool is_safe(CompiledMethod* method) {
  96     if (SafepointSynchronize::is_at_safepoint()) {
  97       return true;
  98     }
  99 
 100     nmethod* const nm = method->as_nmethod();
 101     ZReentrantLock* const lock = ZNMethod::lock_for_nmethod(nm);
 102     return lock->is_owned();
 103   }
 104 };
 105 
 106 ZUnload::ZUnload(ZWorkers* workers) :
 107     _workers(workers) {
 108 
 109   if (!ClassUnloading) {
 110     return;
 111   }
 112 
 113   static ZIsUnloadingBehaviour is_unloading_behaviour;
 114   IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
 115 
 116   static ZCompiledICProtectionBehaviour ic_protection_behaviour;
 117   CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
 118 }
 119 
 120 void ZUnload::prepare() {
 121   if (!ClassUnloading) {
 122     return;
 123   }
 124 
 125   CodeCache::increment_unloading_cycle();
 126   DependencyContext::cleaning_start();
 127 }
 128 
 129 void ZUnload::unlink() {
 130   if (!ClassUnloading) {
 131     return;
 132   }
 133 
 134   ZStatTimer timer(ZSubPhaseConcurrentClassesUnlink);
 135   SuspendibleThreadSetJoiner sts;
 136   bool unloading_occurred;
 137 
 138   {
 139     MutexLocker ml(ClassLoaderDataGraph_lock);
 140     unloading_occurred = SystemDictionary::do_unloading(ZStatPhase::timer());
 141   }
 142 
 143   Klass::clean_weak_klass_links(unloading_occurred);
 144   ZNMethod::unlink(_workers, unloading_occurred);
 145   DependencyContext::cleaning_end();
 146 }
 147 
 148 void ZUnload::purge() {
 149   if (!ClassUnloading) {
 150     return;
 151   }
 152 
 153   ZStatTimer timer(ZSubPhaseConcurrentClassesPurge);
 154 
 155   {
 156     SuspendibleThreadSetJoiner sts;
 157     ZNMethod::purge(_workers);
 158   }
 159 
 160   ClassLoaderDataGraph::purge();
 161   CodeCache::purge_exception_caches();
 162 }
 163 
 164 void ZUnload::finish() {
 165   // Resize and verify metaspace
 166   MetaspaceGC::compute_new_size();
 167   MetaspaceUtils::verify_metrics();
 168 }