1 /* 2 * Copyright (c) 2014, 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 25 #ifndef SHARE_JFR_UTILITIES_JFRTRYLOCK_HPP 26 #define SHARE_JFR_UTILITIES_JFRTRYLOCK_HPP 27 28 #include "runtime/atomic.hpp" 29 #include "runtime/orderAccess.hpp" 30 #include "runtime/mutexLocker.hpp" 31 #include "utilities/debug.hpp" 32 33 class JfrTryLock { 34 private: 35 volatile int* const _lock; 36 bool _has_lock; 37 38 public: JfrTryLock(volatile int * lock)39 JfrTryLock(volatile int* lock) : _lock(lock), _has_lock(Atomic::cmpxchg(lock, 0, 1) == 0) {} 40 ~JfrTryLock()41 ~JfrTryLock() { 42 if (_has_lock) { 43 OrderAccess::fence(); 44 *_lock = 0; 45 } 46 } 47 has_lock() const48 bool has_lock() const { 49 return _has_lock; 50 } 51 }; 52 53 class JfrMonitorTryLock : public StackObj { 54 private: 55 Monitor* _lock; 56 bool _acquired; 57 58 public: JfrMonitorTryLock(Monitor * lock)59 JfrMonitorTryLock(Monitor* lock) : _lock(lock), _acquired(lock->try_lock()) {} 60 ~JfrMonitorTryLock()61 ~JfrMonitorTryLock() { 62 if (_acquired) { 63 assert(_lock->owned_by_self(), "invariant"); 64 _lock->unlock(); 65 } 66 } 67 acquired() const68 bool acquired() const { 69 return _acquired; 70 } 71 72 }; 73 74 #endif // SHARE_JFR_UTILITIES_JFRTRYLOCK_HPP 75