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 /*

  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #ifndef SHARE_VM_UTILITIES_EVENTS_HPP

 #define SHARE_VM_UTILITIES_EVENTS_HPP

 #include "memory/allocation.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "runtime/thread.hpp"

 #include "utilities/top.hpp"

 #include "utilities/vmError.hpp"

 // Events and EventMark provide interfaces to log events taking place in the vm.

 // This facility is extremly useful for post-mortem debugging. The eventlog

 // often provides crucial information about events leading up to the crash.

 //

 // Abstractly the logs can record whatever they way but normally they

 // would record at least a timestamp and the current Thread, along

 // with whatever data they need in a ring buffer.  Commonly fixed

 // length text messages are recorded for simplicity but other

 // strategies could be used.  Several logs are provided by default but

 // new instances can be created as needed.

 // The base event log dumping class that is registered for dumping at

 // crash time.  This is a very generic interface that is mainly here

 // for completeness.  Normally the templated EventLogBase would be

 // subclassed to provide different log types.

 class EventLog : public CHeapObj<mtInternal> {

   friend class Events;

  private:

   EventLog* _next;

   EventLog* next() const { return _next; }

  public:

   // Automatically registers the log so that it will be printed during

   // crashes.

   EventLog();

   virtual void print_log_on(outputStream* out) = 0;

 };

 // A templated subclass of EventLog that provides basic ring buffer

 // functionality.  Most event loggers should subclass this, possibly

 // providing a more featureful log function if the existing copy

 // semantics aren't appropriate.  The name is used as the label of the

 // log when it is dumped during a crash.

 template <class T> class EventLogBase : public EventLog {

   template <class X> class EventRecord {

    public:

     double  timestamp;

     Thread* thread;

     X       data;

   };

  protected:

   Mutex           _mutex;

   const char*     _name;

   int             _length;

   int             _index;

   int             _count;

   EventRecord<T>* _records;

  public:

   EventLogBase<T>(const char* name, int length = LogEventsBufferEntries):

     _name(name),

     _length(length),

     _count(0),

     _index(0),

     _mutex(Mutex::event, name) {

     _records = new EventRecord<T>[length];

   }

   double fetch_timestamp() {

     return os::elapsedTime();

   }

   // move the ring buffer to next open slot and return the index of

   // the slot to use for the current message.  Should only be called

   // while mutex is held.

   int compute_log_index() {

     int index = _index;

     if (_count < _length) _count++;

     _index++;

     if (_index >= _length) _index = 0;

     return index;

   }

   bool should_log() {

     // Don't bother adding new entries when we're crashing.  This also

     // avoids mutating the ring buffer when printing the log.

     return !VMError::fatal_error_in_progress();

   }

   // Print the contents of the log

   void print_log_on(outputStream* out);

  private:

   void print_log_impl(outputStream* out);

   // Print a single element.  A templated implementation might need to

   // be declared by subclasses.

   void print(outputStream* out, T& e);

   void print(outputStream* out, EventRecord<T>& e) {

     out->print("Event: %.3f ", e.timestamp);

     if (e.thread != NULL) {

       out->print("Thread " INTPTR_FORMAT " ", e.thread);

     }

     print(out, e.data);

   }

 };

 // A simple wrapper class for fixed size text messages.

 class StringLogMessage : public FormatBuffer<132> {

  public:

   // Wrap this buffer in a stringStream.

   stringStream stream() {

     return stringStream(_buf, sizeof(_buf));

   }

 };

 // A simple ring buffer of fixed size text messages.

 class StringEventLog : public EventLogBase<StringLogMessage> {

  public:

   StringEventLog(const char* name, int count = LogEventsBufferEntries) : EventLogBase<StringLogMessage>(name, count) {}

   void logv(Thread* thread, const char* format, va_list ap) {

     if (!should_log()) return;

     double timestamp = fetch_timestamp();

     MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);

     int index = compute_log_index();

     _records[index].thread = thread;

     _records[index].timestamp = timestamp;

     _records[index].data.printv(format, ap);

   }

   void log(Thread* thread, const char* format, ...) {

     va_list ap;

     va_start(ap, format);

     logv(thread, format, ap);

     va_end(ap);

   }

 };

 class Events : AllStatic {

   friend class EventLog;

  private:

   static EventLog* _logs;

   // A log for generic messages that aren't well categorized.

   static StringEventLog* _messages;

   // A log for internal exception related messages, like internal

   // throws and implicit exceptions.

   static StringEventLog* _exceptions;

   // Deoptization related messages

   static StringEventLog* _deopt_messages;

  public:

   static void print_all(outputStream* out);

   // Dump all events to the tty

   static void print();

   // Logs a generic message with timestamp and format as printf.

   static void log(Thread* thread, const char* format, ...);

   // Log exception related message

   static void log_exception(Thread* thread, const char* format, ...);

   static void log_deopt_message(Thread* thread, const char* format, ...);

   // Register default loggers

   static void init();

 };

 inline void Events::log(Thread* thread, const char* format, ...) {

   if (LogEvents) {

     va_list ap;

     va_start(ap, format);

     _messages->logv(thread, format, ap);

     va_end(ap);

   }

 }

 inline void Events::log_exception(Thread* thread, const char* format, ...) {

   if (LogEvents) {

     va_list ap;

     va_start(ap, format);

     _exceptions->logv(thread, format, ap);

     va_end(ap);

   }

 }

 inline void Events::log_deopt_message(Thread* thread, const char* format, ...) {

   if (LogEvents) {

     va_list ap;

     va_start(ap, format);

     _deopt_messages->logv(thread, format, ap);

     va_end(ap);

   }

 }

 template <class T>

 inline void EventLogBase<T>::print_log_on(outputStream* out) {

   if (ThreadLocalStorage::get_thread_slow() == NULL) {

     // Not a regular Java thread so don't bother locking

     print_log_impl(out);

   } else {

     MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);

     print_log_impl(out);

   }

 }

 // Dump the ring buffer entries that current have entries.

 template <class T>

 inline void EventLogBase<T>::print_log_impl(outputStream* out) {

   out->print_cr("%s (%d events):", _name, _count);

   if (_count == 0) {

     out->print_cr("No events");

     out->cr();

     return;

   }

   if (_count < _length) {

     for (int i = 0; i < _count; i++) {

       print(out, _records[i]);

     }

   } else {

     for (int i = _index; i < _length; i++) {

       print(out, _records[i]);

     }

     for (int i = 0; i < _index; i++) {

       print(out, _records[i]);

     }

   }

   out->cr();

 }

 // Implement a printing routine for the StringLogMessage

 template <>

 inline void EventLogBase<StringLogMessage>::print(outputStream* out, StringLogMessage& lm) {

   out->print_raw(lm);

   out->cr();

 }

 // Place markers for the beginning and end up of a set of events.

 // These end up in the default log.

 class EventMark : public StackObj {

   StringLogMessage _buffer;

  public:

   // log a begin event, format as printf

   EventMark(const char* format, ...);

   // log an end event

   ~EventMark();

 };

 #endif // SHARE_VM_UTILITIES_EVENTS_HPP