1 /* 2 * Copyright (c) 2016, 2021, 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_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP 26 #define SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP 27 28 #include "jfr/utilities/jfrSignal.hpp" 29 #include "jfr/utilities/jfrTypes.hpp" 30 #include "memory/allocation.hpp" 31 #include "runtime/atomic.hpp" 32 33 #define BIT 1 34 #define METHOD_BIT (BIT << 2) 35 #define EPOCH_0_SHIFT 0 36 #define EPOCH_1_SHIFT 1 37 #define EPOCH_0_BIT (BIT << EPOCH_0_SHIFT) 38 #define EPOCH_1_BIT (BIT << EPOCH_1_SHIFT) 39 #define EPOCH_0_METHOD_BIT (METHOD_BIT << EPOCH_0_SHIFT) 40 #define EPOCH_1_METHOD_BIT (METHOD_BIT << EPOCH_1_SHIFT) 41 #define METHOD_AND_CLASS_BITS (METHOD_BIT | BIT) 42 #define EPOCH_0_METHOD_AND_CLASS_BITS (METHOD_AND_CLASS_BITS << EPOCH_0_SHIFT) 43 #define EPOCH_1_METHOD_AND_CLASS_BITS (METHOD_AND_CLASS_BITS << EPOCH_1_SHIFT) 44 45 // Epoch alternation on each rotation allow for concurrent tagging. 46 // The epoch shift happens only during a safepoint. 47 // 48 // _synchronizing is a transition state, the purpose of which is to 49 // have JavaThreads that run _thread_in_native (i.e. Compiler threads) 50 // respect the current epoch shift in-progress during the safepoint. 51 // 52 // _changed_tag_state == true signals an incremental modification to artifact tagging 53 // (klasses, methods, CLDs, etc), purpose of which is to trigger collection of artifacts. 54 // 55 class JfrTraceIdEpoch : AllStatic { 56 friend class JfrCheckpointManager; 57 private: 58 static JfrSignal _tag_state; 59 static bool _epoch_state; 60 static bool _synchronizing; 61 62 static void begin_epoch_shift(); 63 static void end_epoch_shift(); 64 65 public: epoch()66 static bool epoch() { 67 return _epoch_state; 68 } 69 epoch_address()70 static address epoch_address() { 71 return (address)&_epoch_state; 72 } 73 current()74 static u1 current() { 75 return _epoch_state ? (u1)1 : (u1)0; 76 } 77 previous()78 static u1 previous() { 79 return _epoch_state ? (u1)0 : (u1)1; 80 } 81 is_synchronizing()82 static bool is_synchronizing() { 83 return Atomic::load_acquire(&_synchronizing); 84 } 85 this_epoch_bit()86 static traceid this_epoch_bit() { 87 return _epoch_state ? EPOCH_1_BIT : EPOCH_0_BIT; 88 } 89 previous_epoch_bit()90 static traceid previous_epoch_bit() { 91 return _epoch_state ? EPOCH_0_BIT : EPOCH_1_BIT; 92 } 93 this_epoch_method_bit()94 static traceid this_epoch_method_bit() { 95 return _epoch_state ? EPOCH_1_METHOD_BIT : EPOCH_0_METHOD_BIT; 96 } 97 previous_epoch_method_bit()98 static traceid previous_epoch_method_bit() { 99 return _epoch_state ? EPOCH_0_METHOD_BIT : EPOCH_1_METHOD_BIT; 100 } 101 this_epoch_method_and_class_bits()102 static traceid this_epoch_method_and_class_bits() { 103 return _epoch_state ? EPOCH_1_METHOD_AND_CLASS_BITS : EPOCH_0_METHOD_AND_CLASS_BITS; 104 } 105 previous_epoch_method_and_class_bits()106 static traceid previous_epoch_method_and_class_bits() { 107 return _epoch_state ? EPOCH_0_METHOD_AND_CLASS_BITS : EPOCH_1_METHOD_AND_CLASS_BITS; 108 } 109 has_changed_tag_state()110 static bool has_changed_tag_state() { 111 return _tag_state.is_signaled_with_reset(); 112 } 113 has_changed_tag_state_no_reset()114 static bool has_changed_tag_state_no_reset() { 115 return _tag_state.is_signaled(); 116 } 117 set_changed_tag_state()118 static void set_changed_tag_state() { 119 _tag_state.signal(); 120 } 121 signal_address()122 static address signal_address() { 123 return _tag_state.signaled_address(); 124 } 125 }; 126 127 #endif // SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP 128