1 /*
2 * Copyright (c) 1997, 2012, 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/top.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 // All arguments past the format string must be passed as an intptr_t.
39 //
40 // To log a single event use:
41 // Events::log("New nmethod has been created " INTPTR_FORMAT, nm);
42 //
43 // To log a block of events use:
44 // EventMark m("GarbageCollecting %d", (intptr_t)gc_number);
45 //
46 // The constructor to eventlog indents the eventlog until the
47 // destructor has been executed.
48 //
49 // IMPLEMENTATION RESTRICTION:
50 // Max 3 arguments are saved for each logged event.
51 //
52
53 // The base event log dumping class that is registered for dumping at
54 // crash time. This is a very generic interface that is mainly here
55 // for completeness. Normally the templated EventLogBase would be
56 // subclassed to provide different log types.
57 class EventLog : public CHeapObj {
58 friend class Events;
59
60 private:
61 EventLog* _next;
62
63 EventLog* next() const { return _next; }
64
65 public:
66 // Automatically registers the log so that it will be printed during
67 // crashes.
68 EventLog();
69
70 virtual void print_log_on(outputStream* out) = 0;
71 };
72
73
74 // A templated subclass of EventLog that provides basic ring buffer
75 // functionality. Most event loggers should subclass this, possibly
76 // providing a more featureful log function if the existing copy
77 // semantics aren't appropriate. The name is used as the label of the
78 // log when it is dumped during a crash.
79 template <class T> class EventLogBase : public EventLog {
80 template <class X> class EventRecord {
81 public:
82 jlong timestamp;
83 Thread* thread;
84 X data;
85 };
86
87 protected:
88 Mutex _mutex;
89 const char* _name;
90 int _length;
91 int _index;
92 int _count;
93 EventRecord<T>* _records;
94
95 public:
96 EventLogBase<T>(const char* name, int length = LogEventsBufferEntries):
97 _name(name),
98 _length(length),
99 _count(0),
100 _index(0),
101 _mutex(Mutex::event, name) {
102 _records = new EventRecord<T>[length];
103 }
104
105 // move the ring buffer to next open slot and return the index of
106 // the slot to use for the current message. Should only be called
107 // while mutex is held.
108 int compute_log_index() {
109 int index = _index;
110 if (_count < _length) _count++;
111 _index++;
112 if (_index >= _length) _index = 0;
113 return index;
114 }
115
116 bool should_log() {
117 // Don't bother adding new entries when we're crashing. This also
118 // avoids mutating the ring buffer when printing the log.
119 return !VMError::fatal_error_in_progress();
120 }
121
122 // Print the contents of the log
123 void print_log_on(outputStream* out);
124
125 private:
126 void print_log_impl(outputStream* out);
127
128 // Print a single element. A templated implementation might need to
129 // be declared by subclasses.
130 void print(outputStream* out, T& e);
131
132 void print(outputStream* out, EventRecord<T>& e) {
133 out->print("Event: " INT64_FORMAT " ", e.timestamp);
134 if (e.thread != NULL) {
135 out->print("Thread " INTPTR_FORMAT " ", e.thread);
136 }
137 print(out, e.data);
138 }
139 };
140
141 // A simple wrapper class for fixed size text messages.
142 class StringLogMessage : public FormatBuffer<132> {
143 public:
144 // Wrap this buffer in a stringStream.
145 stringStream stream() {
146 return stringStream(_buf, sizeof(_buf));
147 }
148 };
149
150 // A simple ring buffer of fixed size text messages.
151 class StringEventLog : public EventLogBase<StringLogMessage> {
152 public:
153 StringEventLog(const char* name, int count = LogEventsBufferEntries) : EventLogBase<StringLogMessage>(name, count) {}
154
155 void logv(Thread* thread, const char* format, va_list ap) {
156 if (!should_log()) return;
157
158 jlong timestamp = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
159 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
160 int index = compute_log_index();
161 _records[index].thread = thread;
162 _records[index].timestamp = timestamp;
163 _records[index].data.printv(format, ap);
164 }
165
166 void log(Thread* thread, const char* format, ...) {
167 va_list ap;
168 va_start(ap, format);
169 logv(thread, format, ap);
170 va_end(ap);
171 }
172
173 };
174
175
176
177 class Events : AllStatic {
178 friend class EventLog;
179
180 private:
181 static EventLog* _logs;
182
183 // A log for generic messages that aren't well categorized.
184 static StringEventLog* _messages;
185
186 // A log for internal exception related messages, like internal
187 // throws and implicit exceptions.
188 static StringEventLog* _exceptions;
189
190 // Deoptization related messages
191 static StringEventLog* _deopt_messages;
192
193 public:
194 static void print_all(outputStream* out);
195
196 static void print() {
197 print_all(tty);
198 }
199
200 // Logs a generic message with timestamp and format as printf.
201 static void log(Thread* thread, const char* format, ...);
202
203 // Log exception related message
204 static void log_exception(Thread* thread, const char* format, ...);
205
206 static void log_deopt_message(Thread* thread, const char* format, ...);
207
208 // Register default loggers
209 static void init();
210 };
211
212
213 inline void Events::log(Thread* thread, const char* format, ...) {
214 if (LogEvents) {
215 va_list ap;
216 va_start(ap, format);
217 _messages->logv(thread, format, ap);
218 va_end(ap);
219 }
220 }
221
222 inline void Events::log_exception(Thread* thread, const char* format, ...) {
223 if (LogEvents) {
224 va_list ap;
225 va_start(ap, format);
226 _exceptions->logv(thread, format, ap);
227 va_end(ap);
228 }
229 }
230
231 inline void Events::log_deopt_message(Thread* thread, const char* format, ...) {
232 if (LogEvents) {
233 va_list ap;
234 va_start(ap, format);
235 _deopt_messages->logv(thread, format, ap);
236 va_end(ap);
237 }
238 }
239
240
241 template <class T>
242 inline void EventLogBase<T>::print_log_on(outputStream* out) {
243 if (ThreadLocalStorage::get_thread_slow() == NULL) {
244 // Not a regular Java thread so don't bother locking
245 print_log_impl(out);
246 } else {
247 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
248 print_log_impl(out);
249 }
250 }
251
252 // Dump the ring buffer entries that current have entries.
253 template <class T>
254 inline void EventLogBase<T>::print_log_impl(outputStream* out) {
255 out->print_cr("%s (%d events):", _name, _count);
256 if (_count == 0) {
257 out->print_cr("No events");
258 return;
259 }
260
261 if (_count < _length) {
262 for (int i = 0; i < _count; i++) {
263 print(out, _records[i]);
264 }
265 } else {
266 for (int i = _index; i < _length; i++) {
267 print(out, _records[i]);
268 }
269 for (int i = 0; i < _index; i++) {
270 print(out, _records[i]);
271 }
272 }
273 out->cr();
274 }
275
276 // Implement a printing routine for the StringLogMessage
277 template <>
278 inline void EventLogBase<StringLogMessage>::print(outputStream* out, StringLogMessage& lm) {
279 out->print_raw(lm);
280 out->cr();
281 }
282
283 // Place markers for the beginning and end up of a set of events.
284 // These end up in the default log.
285 class EventMark : public StackObj {
286 StringLogMessage _buffer;
287
288 public:
289 // log a begin event, format as printf
290 EventMark(const char* format, ...);
291 // log an end event
292 ~EventMark();
293 };
294
295 #endif // SHARE_VM_UTILITIES_EVENTS_HPP