1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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   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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * or visit www.oracle.com if you need additional information or have any
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  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/globalDefinitions.hpp"
  33 #include "utilities/ostream.hpp"
  34 #include "utilities/vmError.hpp"
  35 
  36 // Events and EventMark provide interfaces to log events taking place in the vm.
  37 // This facility is extremly useful for post-mortem debugging. The eventlog
  38 // often provides crucial information about events leading up to the crash.
  39 //
  40 // Abstractly the logs can record whatever they way but normally they
  41 // would record at least a timestamp and the current Thread, along
  42 // with whatever data they need in a ring buffer.  Commonly fixed
  43 // length text messages are recorded for simplicity but other
  44 // strategies could be used.  Several logs are provided by default but
  45 // new instances can be created as needed.
  46 
  47 // The base event log dumping class that is registered for dumping at
  48 // crash time.  This is a very generic interface that is mainly here
  49 // for completeness.  Normally the templated EventLogBase would be
  50 // subclassed to provide different log types.
  51 class EventLog : public CHeapObj<mtInternal> {
  52   friend class Events;
  53 
  54  private:
  55   EventLog* _next;
  56 
  57   EventLog* next() const { return _next; }
  58 
  59  public:
  60   // Automatically registers the log so that it will be printed during
  61   // crashes.
  62   EventLog();
  63 
  64   // Print log to output stream.
  65   virtual void print_log_on(outputStream* out, int max = -1) = 0;
  66 
  67   // Returns true if s matches either the log name or the log handle.
  68   virtual bool matches_name_or_handle(const char* s) const = 0;
  69 
  70   // Print log names (for help output of VM.events).
  71   virtual void print_names(outputStream* out) const = 0;
  72 
  73 };
  74 
  75 
  76 // A templated subclass of EventLog that provides basic ring buffer
  77 // functionality.  Most event loggers should subclass this, possibly
  78 // providing a more featureful log function if the existing copy
  79 // semantics aren't appropriate.  The name is used as the label of the
  80 // log when it is dumped during a crash.
  81 template <class T> class EventLogBase : public EventLog {
  82   template <class X> class EventRecord : public CHeapObj<mtInternal> {
  83    public:
  84     double  timestamp;
  85     Thread* thread;
  86     X       data;
  87   };
  88 
  89  protected:
  90   Mutex           _mutex;
  91   // Name is printed out as a header.
  92   const char*     _name;
  93   // Handle is a short specifier used to select this particular event log
  94   // for printing (see VM.events command).
  95   const char*     _handle;
  96   int             _length;
  97   int             _index;
  98   int             _count;
  99   EventRecord<T>* _records;
 100 
 101  public:
 102   EventLogBase<T>(const char* name, const char* handle, int length = LogEventsBufferEntries):
 103     _mutex(Mutex::event, name, false, Monitor::_safepoint_check_never),
 104     _name(name),
 105     _handle(handle),
 106     _length(length),
 107     _index(0),
 108     _count(0) {
 109     _records = new EventRecord<T>[length];
 110   }
 111 
 112   double fetch_timestamp() {
 113     return os::elapsedTime();
 114   }
 115 
 116   // move the ring buffer to next open slot and return the index of
 117   // the slot to use for the current message.  Should only be called
 118   // while mutex is held.
 119   int compute_log_index() {
 120     int index = _index;
 121     if (_count < _length) _count++;
 122     _index++;
 123     if (_index >= _length) _index = 0;
 124     return index;
 125   }
 126 
 127   bool should_log() {
 128     // Don't bother adding new entries when we're crashing.  This also
 129     // avoids mutating the ring buffer when printing the log.
 130     return !VMError::fatal_error_in_progress();
 131   }
 132 
 133   // Print the contents of the log
 134   void print_log_on(outputStream* out, int max = -1);
 135 
 136   // Returns true if s matches either the log name or the log handle.
 137   bool matches_name_or_handle(const char* s) const;
 138 
 139   // Print log names (for help output of VM.events).
 140   void print_names(outputStream* out) const;
 141 
 142  private:
 143   void print_log_impl(outputStream* out, int max = -1);
 144 
 145   // Print a single element.  A templated implementation might need to
 146   // be declared by subclasses.
 147   void print(outputStream* out, T& e);
 148 
 149   void print(outputStream* out, EventRecord<T>& e) {
 150     out->print("Event: %.3f ", e.timestamp);
 151     if (e.thread != NULL) {
 152       out->print("Thread " INTPTR_FORMAT " ", p2i(e.thread));
 153     }
 154     print(out, e.data);
 155   }
 156 };
 157 
 158 // A simple wrapper class for fixed size text messages.
 159 template <size_t bufsz>
 160 class FormatStringLogMessage : public FormatBuffer<bufsz> {
 161 };
 162 typedef FormatStringLogMessage<256> StringLogMessage;
 163 typedef FormatStringLogMessage<512> ExtendedStringLogMessage;
 164 
 165 // A simple ring buffer of fixed size text messages.
 166 template <size_t bufsz>
 167 class FormatStringEventLog : public EventLogBase< FormatStringLogMessage<bufsz> > {
 168  public:
 169   FormatStringEventLog(const char* name, const char* short_name, int count = LogEventsBufferEntries)
 170    : EventLogBase< FormatStringLogMessage<bufsz> >(name, short_name, count) {}
 171 
 172   void logv(Thread* thread, const char* format, va_list ap) ATTRIBUTE_PRINTF(3, 0) {
 173     if (!this->should_log()) return;
 174 
 175     double timestamp = this->fetch_timestamp();
 176     MutexLocker ml(&this->_mutex, Mutex::_no_safepoint_check_flag);
 177     int index = this->compute_log_index();
 178     this->_records[index].thread = thread;
 179     this->_records[index].timestamp = timestamp;
 180     this->_records[index].data.printv(format, ap);
 181   }
 182 
 183   void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(3, 4) {
 184     va_list ap;
 185     va_start(ap, format);
 186     this->logv(thread, format, ap);
 187     va_end(ap);
 188   }
 189 };
 190 typedef FormatStringEventLog<256> StringEventLog;
 191 typedef FormatStringEventLog<512> ExtendedStringEventLog;
 192 
 193 class InstanceKlass;
 194 
 195 // Event log for class unloading events to materialize the class name in place in the log stream.
 196 class UnloadingEventLog : public EventLogBase<StringLogMessage> {
 197  public:
 198   UnloadingEventLog(const char* name, const char* short_name, int count = LogEventsBufferEntries)
 199    : EventLogBase<StringLogMessage>(name, short_name, count) {}
 200 
 201   void log(Thread* thread, InstanceKlass* ik);
 202 };
 203 
 204 // Event log for exceptions
 205 class ExceptionsEventLog : public ExtendedStringEventLog {
 206  public:
 207   ExceptionsEventLog(const char* name, const char* short_name, int count = LogEventsBufferEntries)
 208    : ExtendedStringEventLog(name, short_name, count) {}
 209 
 210   void log(Thread* thread, Handle h_exception, const char* message, const char* file, int line);
 211 };
 212 
 213 
 214 class Events : AllStatic {
 215   friend class EventLog;
 216 
 217  private:
 218   static EventLog* _logs;
 219 
 220   // A log for generic messages that aren't well categorized.
 221   static StringEventLog* _messages;
 222 
 223   // A log for internal exception related messages, like internal
 224   // throws and implicit exceptions.
 225   static ExceptionsEventLog* _exceptions;
 226 
 227   // Deoptization related messages
 228   static StringEventLog* _deopt_messages;
 229 
 230   // Redefinition related messages
 231   static StringEventLog* _redefinitions;
 232 
 233   // Class unloading events
 234   static UnloadingEventLog* _class_unloading;
 235  public:
 236 
 237   // Print all event logs; limit number of events per event log to be printed with max
 238   // (max == -1 prints all events).
 239   static void print_all(outputStream* out, int max = -1);
 240 
 241   // Print a single event log specified by name or handle.
 242   static void print_one(outputStream* out, const char* log_name, int max = -1);
 243 
 244   // Dump all events to the tty
 245   static void print();
 246 
 247   // Logs a generic message with timestamp and format as printf.
 248   static void log(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 249 
 250   // Log exception related message
 251   static void log_exception(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 252   static void log_exception(Thread* thread, Handle h_exception, const char* message, const char* file, int line);
 253 
 254   static void log_redefinition(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 255 
 256   static void log_class_unloading(Thread* thread, InstanceKlass* ik);
 257 
 258   static void log_deopt_message(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 259 
 260   // Register default loggers
 261   static void init();
 262 };
 263 
 264 inline void Events::log(Thread* thread, const char* format, ...) {
 265   if (LogEvents && _messages != NULL) {
 266     va_list ap;
 267     va_start(ap, format);
 268     _messages->logv(thread, format, ap);
 269     va_end(ap);
 270   }
 271 }
 272 
 273 inline void Events::log_exception(Thread* thread, const char* format, ...) {
 274   if (LogEvents && _exceptions != NULL) {
 275     va_list ap;
 276     va_start(ap, format);
 277     _exceptions->logv(thread, format, ap);
 278     va_end(ap);
 279   }
 280 }
 281 
 282 inline void Events::log_exception(Thread* thread, Handle h_exception, const char* message, const char* file, int line) {
 283   if (LogEvents && _exceptions != NULL) {
 284     _exceptions->log(thread, h_exception, message, file, line);
 285   }
 286 }
 287 
 288 inline void Events::log_redefinition(Thread* thread, const char* format, ...) {
 289   if (LogEvents && _redefinitions != NULL) {
 290     va_list ap;
 291     va_start(ap, format);
 292     _redefinitions->logv(thread, format, ap);
 293     va_end(ap);
 294   }
 295 }
 296 
 297 inline void Events::log_class_unloading(Thread* thread, InstanceKlass* ik) {
 298   if (LogEvents && _class_unloading != NULL) {
 299     _class_unloading->log(thread, ik);
 300   }
 301 }
 302 
 303 inline void Events::log_deopt_message(Thread* thread, const char* format, ...) {
 304   if (LogEvents && _deopt_messages != NULL) {
 305     va_list ap;
 306     va_start(ap, format);
 307     _deopt_messages->logv(thread, format, ap);
 308     va_end(ap);
 309   }
 310 }
 311 
 312 template <class T>
 313 inline void EventLogBase<T>::print_log_on(outputStream* out, int max) {
 314   if (Thread::current_or_null() == NULL) {
 315     // Not yet attached? Don't try to use locking
 316     print_log_impl(out, max);
 317   } else {
 318     MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
 319     print_log_impl(out, max);
 320   }
 321 }
 322 
 323 template <class T>
 324 inline bool EventLogBase<T>::matches_name_or_handle(const char* s) const {
 325   return ::strcasecmp(s, _name) == 0 ||
 326          ::strcasecmp(s, _handle) == 0;
 327 }
 328 
 329 template <class T>
 330 inline void EventLogBase<T>::print_names(outputStream* out) const {
 331   out->print("\"%s\" : %s", _handle, _name);
 332 }
 333 
 334 // Dump the ring buffer entries that current have entries.
 335 template <class T>
 336 inline void EventLogBase<T>::print_log_impl(outputStream* out, int max) {
 337   out->print_cr("%s (%d events):", _name, _count);
 338   if (_count == 0) {
 339     out->print_cr("No events");
 340     out->cr();
 341     return;
 342   }
 343 
 344   int printed = 0;
 345   if (_count < _length) {
 346     for (int i = 0; i < _count; i++) {
 347       if (max > 0 && printed == max) {
 348         break;
 349       }
 350       print(out, _records[i]);
 351       printed ++;
 352     }
 353   } else {
 354     for (int i = _index; i < _length; i++) {
 355       if (max > 0 && printed == max) {
 356         break;
 357       }
 358       print(out, _records[i]);
 359       printed ++;
 360     }
 361     for (int i = 0; i < _index; i++) {
 362       if (max > 0 && printed == max) {
 363         break;
 364       }
 365       print(out, _records[i]);
 366       printed ++;
 367     }
 368   }
 369 
 370   if (printed == max) {
 371     out->print_cr("...(skipped)");
 372   }
 373 
 374   out->cr();
 375 }
 376 
 377 // Implement a printing routine for the StringLogMessage
 378 template <>
 379 inline void EventLogBase<StringLogMessage>::print(outputStream* out, StringLogMessage& lm) {
 380   out->print_raw(lm);
 381   out->cr();
 382 }
 383 
 384 // Implement a printing routine for the ExtendedStringLogMessage
 385 template <>
 386 inline void EventLogBase<ExtendedStringLogMessage>::print(outputStream* out, ExtendedStringLogMessage& lm) {
 387   out->print_raw(lm);
 388   out->cr();
 389 }
 390 
 391 // Place markers for the beginning and end up of a set of events.
 392 // These end up in the default log.
 393 class EventMark : public StackObj {
 394   StringLogMessage _buffer;
 395 
 396  public:
 397   // log a begin event, format as printf
 398   EventMark(const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 399   // log an end event
 400   ~EventMark();
 401 };
 402 
 403 #endif // SHARE_UTILITIES_EVENTS_HPP