1 /* 2 * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates. 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 "gc/shenandoah/shenandoahJNICritical.hpp" 25 #include "gc/shenandoah/shenandoahHeap.hpp" 26 27 #include "gc/shared/gcLocker.hpp" 28 #include "runtime/mutexLocker.hpp" 29 #include "runtime/thread.hpp" 30 #include "runtime/vmThread.hpp" 31 32 class VM_ShenandoahJNICriticalOperation : public VM_Operation { 33 private: 34 VM_Operation* _target; 35 public: 36 VM_ShenandoahJNICriticalOperation(VM_Operation* target); 37 VMOp_Type type() const; 38 bool doit_prologue(); 39 void doit_epilogue(); 40 void doit(); 41 const char* name() const; 42 }; 43 44 ShenandoahJNICritical::ShenandoahJNICritical() : _op_waiting_for_jni_critical(NULL) { 45 } 46 47 /* 48 * This is called by the Java thread who leaves the last JNI critical block. 49 */ 50 void ShenandoahJNICritical::notify_jni_critical() { 51 assert(Thread::current()->is_Java_thread(), "call only from Java thread"); 52 assert(_op_waiting_for_jni_critical != NULL, "must be waiting for jni critical notification"); 53 54 MonitorLockerEx ml(ShenandoahJNICritical_lock, true); 55 56 VMThread::execute(_op_waiting_for_jni_critical); 57 _op_waiting_for_jni_critical = NULL; 58 59 ml.notify_all(); 60 61 } 62 63 /* 64 * This is called by the VM thread, if it determines that the task must wait 65 * for JNI critical regions to be left. 66 */ 67 void ShenandoahJNICritical::set_waiting_for_jni_before_gc(VM_Operation* op) { 68 assert(Thread::current()->is_VM_thread(), "call only from VM thread"); 69 _op_waiting_for_jni_critical = op; 70 } 71 72 /** 73 * This is called by the Shenandoah concurrent thread in order 74 * to execute a VM_Operation on the VM thread, that needs to perform 75 * a JNI critical region check. 76 */ 77 void ShenandoahJNICritical::execute_in_vm_thread(VM_Operation* op) { 78 MonitorLockerEx ml(ShenandoahJNICritical_lock, true); 79 VM_ShenandoahJNICriticalOperation jni_op(op); 80 VMThread::execute(&jni_op); 81 while (_op_waiting_for_jni_critical != NULL) { 82 ml.wait(true); 83 } 84 } 85 86 87 VM_ShenandoahJNICriticalOperation::VM_ShenandoahJNICriticalOperation(VM_Operation* target) 88 : _target(target) { 89 } 90 91 VM_Operation::VMOp_Type VM_ShenandoahJNICriticalOperation::type() const { 92 return _target->type(); 93 } 94 95 const char* VM_ShenandoahJNICriticalOperation::name() const { 96 return _target->name(); 97 } 98 99 bool VM_ShenandoahJNICriticalOperation::doit_prologue() { 100 return _target->doit_prologue(); 101 } 102 103 void VM_ShenandoahJNICriticalOperation::doit_epilogue() { 104 _target->doit_epilogue(); 105 } 106 107 void VM_ShenandoahJNICriticalOperation::doit() { 108 if (! GC_locker::check_active_before_gc()) { 109 _target->doit(); 110 } else { 111 112 if (ShenandoahTraceJNICritical) { 113 gclog_or_tty->print_cr("Deferring JNI critical op because of active JNI critical regions"); 114 } 115 116 // This makes the GC background thread wait, and kick off evacuation as 117 // soon as JNI notifies us that critical regions have all been left. 118 ShenandoahHeap *sh = ShenandoahHeap::heap(); 119 sh->jni_critical()->set_waiting_for_jni_before_gc(this); 120 } 121 }