7141200: log some interesting information in ring buffers for crashes

Reviewed-by: kvn, jrose, kevinw, brutisso, twisti, jmasa

hotspot/src/share/vm/utilities/events.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -26,7 +26,10 @@
 #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
@@ -47,26 +50,246 @@
 //   Max 3 arguments are saved for each logged event.
 //
 
-class Events : AllStatic {
+// 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 {
+  friend class Events;
+
+ private:
+  EventLog* _next;
+
+  EventLog* next() const { return _next; }
+
  public:
-  // Logs an event, format as printf
-  static void log(const char* format, ...) PRODUCT_RETURN;
+  // Automatically registers the log so that it will be printed during
+  // crashes.
+  EventLog();
 
-  // Prints all events in the buffer
-  static void print_all(outputStream* st) PRODUCT_RETURN;
-
-  // Prints last number events from the event buffer
-  static void print_last(outputStream *st, int number) PRODUCT_RETURN;
+  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:
+    jlong   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];
+  }
+
+  // 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: " INT64_FORMAT " ", 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;
+
+    jlong timestamp = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+    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);
+
+  static void print() {
+    print_all(tty);
+  }
+
+  // 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");
+    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, ...) PRODUCT_RETURN;
+  EventMark(const char* format, ...);
   // log an end event
-  ~EventMark() PRODUCT_RETURN;
+  ~EventMark();
 };
 
-int print_all_events(outputStream *st);
-
 #endif // SHARE_VM_UTILITIES_EVENTS_HPP