1/* 2 * Copyright (c) 1997, 2017, 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_VM_UTILITIES_EVENTS_HPP 26#define SHARE_VM_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. 49class 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. 71template <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 _name(name), 90 _length(length), 91 _count(0), 92 _index(0), 93 _mutex(Mutex::event, name, false, Monitor::_safepoint_check_never) { 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. 138class StringLogMessage : public FormatBuffer<256> { 139 public: 140 // Wrap this buffer in a stringStream. 141 stringStream stream() { 142 return stringStream(_buf, size()); 143 } 144}; 145 146// A simple ring buffer of fixed size text messages. 147class StringEventLog : public EventLogBase<StringLogMessage> { 148 public: 149 StringEventLog(const char* name, int count = LogEventsBufferEntries) : EventLogBase<StringLogMessage>(name, count) {} 150 151 void logv(Thread* thread, const char* format, va_list ap) ATTRIBUTE_PRINTF(3, 0) { 152 if (!should_log()) return; 153 154 double timestamp = fetch_timestamp(); 155 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); 156 int index = compute_log_index(); 157 _records[index].thread = thread; 158 _records[index].timestamp = timestamp; 159 _records[index].data.printv(format, ap); 160 } 161 162 void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(3, 4) { 163 va_list ap; 164 va_start(ap, format); 165 logv(thread, format, ap); 166 va_end(ap); 167 } 168 169}; 170 171 172 173class Events : AllStatic { 174 friend class EventLog; 175 176 private: 177 static EventLog* _logs; 178 179 // A log for generic messages that aren't well categorized. 180 static StringEventLog* _messages; 181 182 // A log for internal exception related messages, like internal 183 // throws and implicit exceptions. 184 static StringEventLog* _exceptions; 185 186 // Deoptization related messages 187 static StringEventLog* _deopt_messages; 188 189 // Redefinition related messages 190 static StringEventLog* _redefinitions; 191 192 public: 193 static void print_all(outputStream* out); 194 195 // Dump all events to the tty 196 static void print(); 197 198 // Logs a generic message with timestamp and format as printf. 199 static void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 200 201 // Log exception related message 202 static void log_exception(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 203 204 static void log_redefinition(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 205 206 static void log_deopt_message(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 207 208 // Register default loggers 209 static void init(); 210}; 211 212inline void Events::log(Thread* thread, const char* format, ...) { 213 if (LogEvents) { 214 va_list ap; 215 va_start(ap, format); 216 _messages->logv(thread, format, ap); 217 va_end(ap); 218 } 219} 220 221inline void Events::log_exception(Thread* thread, const char* format, ...) { 222 if (LogEvents) { 223 va_list ap; 224 va_start(ap, format); 225 _exceptions->logv(thread, format, ap); 226 va_end(ap); 227 } 228} 229 230inline void Events::log_redefinition(Thread* thread, const char* format, ...) { 231 if (LogEvents) { 232 va_list ap; 233 va_start(ap, format); 234 _redefinitions->logv(thread, format, ap); 235 va_end(ap); 236 } 237} 238 239inline void Events::log_deopt_message(Thread* thread, const char* format, ...) { 240 if (LogEvents) { 241 va_list ap; 242 va_start(ap, format); 243 _deopt_messages->logv(thread, format, ap); 244 va_end(ap); 245 } 246} 247 248 249template <class T> 250inline void EventLogBase<T>::print_log_on(outputStream* out) { 251 if (Thread::current_or_null() == NULL) { 252 // Not yet attached? Don't try to use locking 253 print_log_impl(out); 254 } else { 255 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); 256 print_log_impl(out); 257 } 258} 259 260// Dump the ring buffer entries that current have entries. 261template <class T> 262inline void EventLogBase<T>::print_log_impl(outputStream* out) { 263 out->print_cr("%s (%d events):", _name, _count); 264 if (_count == 0) { 265 out->print_cr("No events"); 266 out->cr(); 267 return; 268 } 269 270 if (_count < _length) { 271 for (int i = 0; i < _count; i++) { 272 print(out, _records[i]); 273 } 274 } else { 275 for (int i = _index; i < _length; i++) { 276 print(out, _records[i]); 277 } 278 for (int i = 0; i < _index; i++) { 279 print(out, _records[i]); 280 } 281 } 282 out->cr(); 283} 284 285// Implement a printing routine for the StringLogMessage 286template <> 287inline void EventLogBase<StringLogMessage>::print(outputStream* out, StringLogMessage& lm) { 288 out->print_raw(lm); 289 out->cr(); 290} 291 292// Place markers for the beginning and end up of a set of events. 293// These end up in the default log. 294class EventMark : public StackObj { 295 StringLogMessage _buffer; 296 297 public: 298 // log a begin event, format as printf 299 EventMark(const char* format, ...) ATTRIBUTE_PRINTF(2, 3); 300 // log an end event 301 ~EventMark(); 302}; 303 304#endif // SHARE_VM_UTILITIES_EVENTS_HPP 305