1 /* 2 * Copyright (c) 2017, 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 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHLOCK_HPP 25 #define SHARE_GC_SHENANDOAH_SHENANDOAHLOCK_HPP 26 27 #include "gc/shenandoah/shenandoahPadding.hpp" 28 #include "memory/allocation.hpp" 29 #include "runtime/thread.hpp" 30 31 class ShenandoahLock { 32 private: 33 enum LockState { unlocked = 0, locked = 1 }; 34 35 shenandoah_padding(0); 36 volatile int _state; 37 shenandoah_padding(1); 38 volatile Thread* _owner; 39 shenandoah_padding(2); 40 41 public: 42 ShenandoahLock() : _state(unlocked), _owner(NULL) {}; 43 44 void lock() { 45 #ifdef ASSERT 46 assert(_owner != Thread::current(), "reentrant locking attempt, would deadlock"); 47 #endif 48 Thread::SpinAcquire(&_state, "Shenandoah Heap Lock"); 49 #ifdef ASSERT 50 assert(_state == locked, "must be locked"); 51 assert(_owner == NULL, "must not be owned"); 52 _owner = Thread::current(); 53 #endif 54 } 55 56 void unlock() { 57 #ifdef ASSERT 58 assert (_owner == Thread::current(), "sanity"); 59 _owner = NULL; 60 #endif 61 Thread::SpinRelease(&_state); 62 } 63 64 bool owned_by_self() { 65 #ifdef ASSERT 66 return _state == locked && _owner == Thread::current(); 67 #else 68 ShouldNotReachHere(); 69 return false; 70 #endif 71 } 72 }; 73 74 class ShenandoahLocker : public StackObj { 75 private: 76 ShenandoahLock* const _lock; 77 public: 78 ShenandoahLocker(ShenandoahLock* lock) : _lock(lock) { 79 if (_lock != NULL) { 80 _lock->lock(); 81 } 82 } 83 84 ~ShenandoahLocker() { 85 if (_lock != NULL) { 86 _lock->unlock(); 87 } 88 } 89 }; 90 91 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHLOCK_HPP