1 /* 2 * Copyright (c) 1997, 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_UTILITIES_EVENTS_HPP 26 #define SHARE_UTILITIES_EVENTS_HPP 27 28 #include "memory/allocation.hpp" 29 #include "runtime/mutexLocker.hpp" 30 #include "runtime/thread.hpp" 31 #include "utilities/formatBuffer.hpp" 32 #include "utilities/vmError.hpp" 33 34 // Events and EventMark provide interfaces to log events taking place in the vm. 35 // This facility is extremly useful for post-mortem debugging. The eventlog 36 // often provides crucial information about events leading up to the crash. 37 // 38 // Abstractly the logs can record whatever they way but normally they 39 // would record at least a timestamp and the current Thread, along 40 // with whatever data they need in a ring buffer. Commonly fixed 41 // length text messages are recorded for simplicity but other 42 // strategies could be used. Several logs are provided by default but 43 // new instances can be created as needed. 44 45 // The base event log dumping class that is registered for dumping at 46 // crash time. This is a very generic interface that is mainly here 47 // for completeness. Normally the templated EventLogBase would be 48 // subclassed to provide different log types. 49 class EventLog : public CHeapObj<mtInternal> { 50 friend class Events; 51 52 private: 53 EventLog* _next; 54 55 EventLog* next() const { return _next; } 56 57 public: 58 // Automatically registers the log so that it will be printed during 59 // crashes. 60 EventLog(); 61 62 virtual void print_log_on(outputStream* out) = 0; 63 }; 64 65 66 // A templated subclass of EventLog that provides basic ring buffer 67 // functionality. Most event loggers should subclass this, possibly 68 // providing a more featureful log function if the existing copy 69 // semantics aren't appropriate. The name is used as the label of the 70 // log when it is dumped during a crash. 71 template <class T> class EventLogBase : public EventLog { 72 template <class X> class EventRecord : public CHeapObj<mtInternal> { 73 public: 74 double timestamp; 75 Thread* thread; 76 X data; 77 }; 78 79 protected: 80 Mutex _mutex; 81 const char* _name; 82 int _length; 83 int _index; 84 int _count; 85 EventRecord<T>* _records; 86 87 public: 88 EventLogBase<T>(const char* name, int length = LogEventsBufferEntries): 89 _mutex(Mutex::event, name, false, Monitor::_safepoint_check_never), 90 _name(name), 91 _length(length), 92 _index(0), 93 _count(0) { 94 _records = new EventRecord<T>[length]; 95 } 96 97 double fetch_timestamp() { 98 return os::elapsedTime(); 99 } 100 101 // move the ring buffer to next open slot and return the index of 102 // the slot to use for the current message. Should only be called 103 // while mutex is held. 104 int compute_log_index() { 105 int index = _index; 106 if (_count < _length) _count++; 107 _index++; 108 if (_index >= _length) _index = 0; 109 return index; 110 } 111 112 bool should_log() { 113 // Don't bother adding new entries when we're crashing. This also 114 // avoids mutating the ring buffer when printing the log. 115 return !VMError::fatal_error_in_progress(); 116 } 117 118 // Print the contents of the log 119 void print_log_on(outputStream* out); 120 121 private: 122 void print_log_impl(outputStream* out); 123 124 // Print a single element. A templated implementation might need to 125 // be declared by subclasses. 126 void print(outputStream* out, T& e); 127 128 void print(outputStream* out, EventRecord<T>& e) { 129 out->print("Event: %.3f ", e.timestamp); 130 if (e.thread != NULL) { 131 out->print("Thread " INTPTR_FORMAT " ", p2i(e.thread)); 132 } 133 print(out, e.data); 134 } 135 }; 136 137 // A simple wrapper class for fixed size text messages. 138 template <size_t bufsz> 139 class TemplatedStringLogMessage : public FormatBuffer<bufsz> { 140 public: 141 // Wrap this buffer in a stringStream. 142 stringStream stream() { 143 return stringStream(this->_buf, this->size()); 144 } 145 }; 146 typedef TemplatedStringLogMessage<256> StringLogMessage; 147 typedef TemplatedStringLogMessage<512> ExtendedStringLogMessage; 148 149 // A simple ring buffer of fixed size text messages. 150 template <size_t bufsz> 151 class TemplatedStringEventLog : public EventLogBase< TemplatedStringLogMessage<bufsz> > { 152 public: 153 TemplatedStringEventLog(const char* name, int count = LogEventsBufferEntries) : EventLogBase< TemplatedStringLogMessage<bufsz> >(name, count) {} 154 155 void logv(Thread* thread, const char* format, va_list ap) ATTRIBUTE_PRINTF(3, 0) { 156 if (!this->should_log()) return; 157 158 double timestamp = this->fetch_timestamp(); 159 MutexLockerEx ml(&this->_mutex, Mutex::_no_safepoint_check_flag); 160 int index = this->compute_log_index(); 161 this->_records[index].thread = thread; 162 this->_records[index].timestamp = timestamp; 163 this->_records[index].data.printv(format, ap); 164 } 165 166 void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(3, 4) { 167 va_list ap; 168 va_start(ap, format); 169 this->logv(thread, format, ap); 170 va_end(ap); 171 } 172 }; 173 typedef TemplatedStringEventLog<256> StringEventLog; 174 typedef TemplatedStringEventLog<512> ExtendedStringEventLog; 175 176 class InstanceKlass; 177 178 // Event log for class unloading events to materialize the class name in place in the log stream. 179 class UnloadingEventLog : public EventLogBase<StringLogMessage> { 180 public: 181 UnloadingEventLog(const char* name, int count = LogEventsBufferEntries) : EventLogBase<StringLogMessage>(name, count) {} 182 183 void log(Thread* thread, InstanceKlass* ik); 184 }; 185 186 187 class Events : AllStatic { 188 friend class EventLog; 189 190 private: 191 static EventLog* _logs; 192 193 // A log for generic messages that aren't well categorized. 194 static StringEventLog* _messages; 195 196 // A log for internal exception related messages, like internal 197 // throws and implicit exceptions. 198 static ExtendedStringEventLog* _exceptions; 199 200 // Deoptization related messages 201 static StringEventLog* _deopt_messages; 202 203 // Redefinition related messages 204 static StringEventLog* _redefinitions; 205 206 // Class unloading events 207 static UnloadingEventLog* _class_unloading; 208 public: 209 static void print_all(outputStream* out); 210 211 // Dump all events to the tty 212 static void print(); 213 214 // Logs a generic message with timestamp and format as printf. 215 static void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 216 217 // Log exception related message 218 static void log_exception(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 219 220 static void log_redefinition(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 221 222 static void log_class_unloading(Thread* thread, InstanceKlass* ik); 223 224 static void log_deopt_message(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 225 226 // Register default loggers 227 static void init(); 228 }; 229 230 inline void Events::log(Thread* thread, const char* format, ...) { 231 if (LogEvents) { 232 va_list ap; 233 va_start(ap, format); 234 _messages->logv(thread, format, ap); 235 va_end(ap); 236 } 237 } 238 239 inline void Events::log_exception(Thread* thread, const char* format, ...) { 240 if (LogEvents) { 241 va_list ap; 242 va_start(ap, format); 243 _exceptions->logv(thread, format, ap); 244 va_end(ap); 245 } 246 } 247 248 inline void Events::log_redefinition(Thread* thread, const char* format, ...) { 249 if (LogEvents) { 250 va_list ap; 251 va_start(ap, format); 252 _redefinitions->logv(thread, format, ap); 253 va_end(ap); 254 } 255 } 256 257 inline void Events::log_class_unloading(Thread* thread, InstanceKlass* ik) { 258 if (LogEvents) { 259 _class_unloading->log(thread, ik); 260 } 261 } 262 263 inline void Events::log_deopt_message(Thread* thread, const char* format, ...) { 264 if (LogEvents) { 265 va_list ap; 266 va_start(ap, format); 267 _deopt_messages->logv(thread, format, ap); 268 va_end(ap); 269 } 270 } 271 272 273 template <class T> 274 inline void EventLogBase<T>::print_log_on(outputStream* out) { 275 if (Thread::current_or_null() == NULL) { 276 // Not yet attached? Don't try to use locking 277 print_log_impl(out); 278 } else { 279 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); 280 print_log_impl(out); 281 } 282 } 283 284 // Dump the ring buffer entries that current have entries. 285 template <class T> 286 inline void EventLogBase<T>::print_log_impl(outputStream* out) { 287 out->print_cr("%s (%d events):", _name, _count); 288 if (_count == 0) { 289 out->print_cr("No events"); 290 out->cr(); 291 return; 292 } 293 294 if (_count < _length) { 295 for (int i = 0; i < _count; i++) { 296 print(out, _records[i]); 297 } 298 } else { 299 for (int i = _index; i < _length; i++) { 300 print(out, _records[i]); 301 } 302 for (int i = 0; i < _index; i++) { 303 print(out, _records[i]); 304 } 305 } 306 out->cr(); 307 } 308 309 // Implement a printing routine for the StringLogMessage 310 template <> 311 inline void EventLogBase<StringLogMessage>::print(outputStream* out, StringLogMessage& lm) { 312 out->print_raw(lm); 313 out->cr(); 314 } 315 316 // Implement a printing routine for the ExtendedStringLogMessage 317 template <> 318 inline void EventLogBase<ExtendedStringLogMessage>::print(outputStream* out, ExtendedStringLogMessage& lm) { 319 out->print_raw(lm); 320 out->cr(); 321 } 322 323 // Place markers for the beginning and end up of a set of events. 324 // These end up in the default log. 325 class EventMark : public StackObj { 326 StringLogMessage _buffer; 327 328 public: 329 // log a begin event, format as printf 330 EventMark(const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 331 // log an end event 332 ~EventMark(); 333 }; 334 335 #endif // SHARE_UTILITIES_EVENTS_HPP