events.cpp revision 1472:c18cbe5936b8 
1/*
2 * Copyright (c) 1997, 2006, 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#include "incls/_precompiled.incl"
26#include "incls/_events.cpp.incl"
27
28
29#ifndef PRODUCT
30
31////////////////////////////////////////////////////////////////////////////
32// Event
33
34typedef u4 EventID;
35
36class Event VALUE_OBJ_CLASS_SPEC  {
37 private:
38  jlong       _time_tick;
39  intx        _thread_id;
40  const char* _format;
41  int         _indent;
42  intptr_t    _arg_1;
43  intptr_t    _arg_2;
44  intptr_t    _arg_3;
45
46  // only EventBuffer::add_event() can assign event id
47  friend class EventBuffer;
48  EventID     _id;
49
50 public:
51
52  void clear() { _format = NULL; }
53
54  EventID id() const { return _id; }
55
56  void fill(int indent, const char* format, intptr_t arg_1, intptr_t arg_2, intptr_t arg_3) {
57    _format = format;
58    _arg_1  = arg_1;
59    _arg_2  = arg_2;
60    _arg_3  = arg_3;
61
62    _indent = indent;
63
64    _thread_id = os::current_thread_id();
65    _time_tick = os::elapsed_counter();
66  }
67
68  void print_on(outputStream *st) {
69    if (_format == NULL) return;
70    st->print("  %d", _thread_id);
71    st->print("  %3.2g   ", (double)_time_tick / os::elapsed_frequency());
72    st->fill_to(20);
73    for (int index = 0; index < _indent; index++) {
74      st->print("| ");
75    }
76    st->print_cr(_format, _arg_1, _arg_2, _arg_3);
77  }
78};
79
80////////////////////////////////////////////////////////////////////////////
81// EventBuffer
82//
83// Simple lock-free event queue. Every event has a unique 32-bit id.
84// It's fine if two threads add events at the same time, because they
85// will get different event id, and then write to different buffer location.
86// However, it is assumed that add_event() is quick enough (or buffer size
87// is big enough), so when one thread is adding event, there can't be more
88// than "size" events created by other threads; otherwise we'll end up having
89// two threads writing to the same location.
90
91class EventBuffer : AllStatic {
92 private:
93  static Event* buffer;
94  static int    size;
95  static jint   indent;
96  static volatile EventID _current_event_id;
97
98  static EventID get_next_event_id() {
99    return (EventID)Atomic::add(1, (jint*)&_current_event_id);
100  }
101
102 public:
103  static void inc_indent() { Atomic::inc(&indent); }
104  static void dec_indent() { Atomic::dec(&indent); }
105
106  static bool get_event(EventID id, Event* event) {
107    int index = (int)(id % size);
108    if (buffer[index].id() == id) {
109      memcpy(event, &buffer[index], sizeof(Event));
110      // check id again; if buffer[index] is being updated by another thread,
111      // event->id() will contain different value.
112      return (event->id() == id);
113    } else {
114      // id does not match - id is invalid, or event is overwritten
115      return false;
116    }
117  }
118
119  // add a new event to the queue; if EventBuffer is full, this call will
120  // overwrite the oldest event in the queue
121  static EventID add_event(const char* format,
122                           intptr_t arg_1, intptr_t arg_2, intptr_t arg_3) {
123    // assign a unique id
124    EventID id = get_next_event_id();
125
126    // event will be copied to buffer[index]
127    int index = (int)(id % size);
128
129    // first, invalidate id, buffer[index] can't have event with id = index + 2
130    buffer[index]._id = index + 2;
131
132    // make sure everyone has seen that buffer[index] is invalid
133    OrderAccess::fence();
134
135    // ... before updating its value
136    buffer[index].fill(indent, format, arg_1, arg_2, arg_3);
137
138    // finally, set up real event id, now buffer[index] contains valid event
139    OrderAccess::release_store(&(buffer[index]._id), id);
140
141    return id;
142  }
143
144  static void print_last(outputStream *st, int number) {
145    st->print_cr("[Last %d events in the event buffer]", number);
146    st->print_cr("-<thd>-<elapsed sec>-<description>---------------------");
147
148    int count = 0;
149    EventID id = _current_event_id;
150    while (count < number) {
151      Event event;
152      if (get_event(id, &event)) {
153         event.print_on(st);
154      }
155      id--;
156      count++;
157    }
158  }
159
160  static void print_all(outputStream* st) {
161    print_last(st, size);
162  }
163
164  static void init() {
165    // Allocate the event buffer
166    size   = EventLogLength;
167    buffer = NEW_C_HEAP_ARRAY(Event, size);
168
169    _current_event_id = 0;
170
171    // Clear the event buffer
172    for (int index = 0; index < size; index++) {
173      buffer[index]._id = index + 1;       // index + 1 is invalid id
174      buffer[index].clear();
175    }
176  }
177};
178
179Event*           EventBuffer::buffer;
180int              EventBuffer::size;
181volatile EventID EventBuffer::_current_event_id;
182int              EventBuffer::indent;
183
184////////////////////////////////////////////////////////////////////////////
185// Events
186
187// Events::log() is safe for signal handlers
188void Events::log(const char* format, ...) {
189  if (LogEvents) {
190    va_list ap;
191    va_start(ap, format);
192    intptr_t arg_1 = va_arg(ap, intptr_t);
193    intptr_t arg_2 = va_arg(ap, intptr_t);
194    intptr_t arg_3 = va_arg(ap, intptr_t);
195    va_end(ap);
196
197    EventBuffer::add_event(format, arg_1, arg_2, arg_3);
198  }
199}
200
201void Events::print_all(outputStream *st) {
202  EventBuffer::print_all(st);
203}
204
205void Events::print_last(outputStream *st, int number) {
206  EventBuffer::print_last(st, number);
207}
208
209///////////////////////////////////////////////////////////////////////////
210// EventMark
211
212EventMark::EventMark(const char* format, ...) {
213  if (LogEvents) {
214    va_list ap;
215    va_start(ap, format);
216    intptr_t arg_1 = va_arg(ap, intptr_t);
217    intptr_t arg_2 = va_arg(ap, intptr_t);
218    intptr_t arg_3 = va_arg(ap, intptr_t);
219    va_end(ap);
220
221    EventBuffer::add_event(format, arg_1, arg_2, arg_3);
222    EventBuffer::inc_indent();
223  }
224}
225
226EventMark::~EventMark() {
227  if (LogEvents) {
228    EventBuffer::dec_indent();
229    EventBuffer::add_event("done", 0, 0, 0);
230  }
231}
232
233///////////////////////////////////////////////////////////////////////////
234
235void eventlog_init() {
236  EventBuffer::init();
237}
238
239int print_all_events(outputStream *st) {
240  EventBuffer::print_all(st);
241  return 1;
242}
243
244#else
245
246void eventlog_init() {}
247int print_all_events(outputStream *st) { return 0; }
248
249#endif // PRODUCT
250