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