GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/tracer.cc
Date: 2025-09-28 02:35:26
Exec Total Coverage
Lines: 159 165 96.4%
Branches: 103 162 63.6%
Line Branch Exec Source
1 /**
2 * This file is part of the CernVM File System.
3 */
4
5
6 #include "tracer.h"
7
8 #include <pthread.h>
9
10 #include <cassert>
11 #include <cerrno>
12 #include <cstdio>
13 #include <cstdlib>
14 #include <cstring>
15 #include <string>
16
17 #include "util/atomic.h"
18 #include "util/concurrency.h"
19 #include "util/posix.h"
20 #include "util/string.h"
21
22 using namespace std; // NOLINT
23
24
25 42 void Tracer::Activate(const int buffer_size,
26 const int flush_threshold,
27 const string &trace_file) {
28 42 trace_file_ = trace_file;
29 42 buffer_size_ = buffer_size;
30 42 flush_threshold_ = flush_threshold;
31
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 42 assert(buffer_size_ > 1 && flush_threshold_ >= 0
32 && flush_threshold_ < buffer_size_);
33
34
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 12624 ring_buffer_ = new BufferEntry[buffer_size_];
35
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 42 commit_buffer_ = new atomic_int32[buffer_size_];
36
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 12624 for (int i = 0; i < buffer_size_; i++)
37 12582 atomic_init32(&commit_buffer_[i]);
38
39 int retval;
40 42 retval = pthread_cond_init(&sig_continue_trace_, NULL);
41 42 retval |= pthread_mutex_init(&sig_continue_trace_mutex_, NULL);
42 42 retval |= pthread_cond_init(&sig_flush_, NULL);
43 42 retval |= pthread_mutex_init(&sig_flush_mutex_, NULL);
44
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 42 assert(retval == 0);
45
46 42 active_ = true;
47 42 }
48
49
50 /**
51 * Trace a message. This is usually a lock-free procedure that just
52 * requires two fetch_and_add operations and a gettimeofday syscall.
53 * There are two exceptions:
54 * -# If the ring buffer is full, the function blocks until the flush
55 * thread made some space. Avoid that by carefully choosing size
56 * and threshold.
57 * -# If this message reaches the threshold, the flush thread gets
58 * signaled.
59 *
60 * \param[in] event Arbitrary code, for consistency applications should use one
61 * of the TraceEvents constants. Negative codes are reserved
62 * for internal use.
63 * \param[in] id Arbitrary id, for example file name or module name which is
64 * doing the trace.
65 * \return The sequence number which was used to trace the record
66 */
67 1002639 int32_t Tracer::DoTrace(const int event,
68 const PathString &path,
69 const string &msg) {
70 1002639 const int32_t my_seq_no = atomic_xadd32(&seq_no_, 1);
71 timeval now;
72 1065639 gettimeofday(&now, NULL);
73 1065276 const int pos = my_seq_no % buffer_size_;
74
75
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 1457100 while (my_seq_no - atomic_read32(&flushed_) >= buffer_size_) {
76 timespec timeout;
77 int retval;
78 377127 GetTimespecRel(25, &timeout);
79 370029 retval = pthread_mutex_lock(&sig_continue_trace_mutex_);
80
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 401313 retval |= pthread_cond_timedwait(&sig_continue_trace_,
81 &sig_continue_trace_mutex_, &timeout);
82 401313 retval |= pthread_mutex_unlock(&sig_continue_trace_mutex_);
83
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 391824 assert(retval == ETIMEDOUT || retval == 0);
84 }
85
86 1065234 ring_buffer_[pos].time_stamp = now;
87 1065234 ring_buffer_[pos].code = event;
88
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 1065234 ring_buffer_[pos].path = path;
89
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 1024140 ring_buffer_[pos].msg = msg;
90 1047354 atomic_inc32(&commit_buffer_[pos]);
91
92
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 1068411 if (my_seq_no - atomic_read32(&flushed_) == flush_threshold_) {
93 109575 const MutexLockGuard m(&sig_flush_mutex_);
94 const int err_code
95 109578 __attribute__((unused)) = pthread_cond_signal(&sig_flush_);
96
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 109578 assert(err_code == 0 && "Could not signal flush thread");
97 109578 }
98
99 1051461 return my_seq_no;
100 }
101
102
103 4251 void Tracer::Flush() {
104
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 4251 if (!active_)
105 ✗ return;
106
107
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 4251 const int32_t save_seq_no = DoTrace(kEventFlush, PathString("Tracer", 6),
108 "flushed ring buffer");
109
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 8352 while (atomic_read32(&flushed_) <= save_seq_no) {
110 timespec timeout;
111 int retval;
112
113 3882 atomic_cas32(&flush_immediately_, 0, 1);
114 {
115 3903 const MutexLockGuard m(&sig_flush_mutex_);
116 3975 retval = pthread_cond_signal(&sig_flush_);
117
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 3975 assert(retval == 0);
118 3975 }
119
120 3969 GetTimespecRel(250, &timeout);
121 3960 retval = pthread_mutex_lock(&sig_continue_trace_mutex_);
122
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 3975 retval |= pthread_cond_timedwait(&sig_continue_trace_,
123 &sig_continue_trace_mutex_, &timeout);
124 3975 retval |= pthread_mutex_unlock(&sig_continue_trace_mutex_);
125
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 3963 assert(retval == ETIMEDOUT || retval == 0);
126 }
127 }
128
129
130 465858 void Tracer::GetTimespecRel(const int64_t ms, timespec *ts) {
131 timeval now;
132 465858 gettimeofday(&now, NULL);
133 466521 int64_t nsecs = now.tv_usec * 1000 + (ms % 1000) * 1000 * 1000;
134 466521 int carry = 0;
135
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 466521 if (nsecs >= 1000 * 1000 * 1000) {
136 2943 carry = 1;
137 2943 nsecs -= 1000 * 1000 * 1000;
138 }
139 466521 ts->tv_sec = now.tv_sec + ms / 1000 + carry;
140 466521 ts->tv_nsec = nsecs;
141 466521 }
142
143
144 42 void *Tracer::MainFlush(void *data) {
145 42 Tracer *tracer = reinterpret_cast<Tracer *>(data);
146 int retval;
147 42 const MutexLockGuard m(&tracer->sig_flush_mutex_);
148
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 42 FILE *f = fopen(tracer->trace_file_.c_str(), "a");
149
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 42 assert(f != NULL && "Could not open trace file");
150 struct timespec timeout;
151
152 do {
153 269556 while (
154 359499 (atomic_read32(&tracer->terminate_flush_thread_) == 0)
155
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 359457 && (atomic_read32(&tracer->flush_immediately_) == 0)
156
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 1077168 && (atomic_read32(&tracer->seq_no_) - atomic_read32(&tracer->flushed_)
157
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 358212 <= tracer->flush_threshold_)) {
158 89943 tracer->GetTimespecRel(2000, &timeout);
159
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 89943 retval = pthread_cond_timedwait(&tracer->sig_flush_,
160 &tracer->sig_flush_mutex_, &timeout);
161
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 89943 assert(retval != EINVAL);
162 }
163
164 269556 const int base = atomic_read32(&tracer->flushed_) % tracer->buffer_size_;
165 269556 int pos, i = 0;
166 269556 while ((i <= tracer->flush_threshold_)
167
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 2610588 && (atomic_read32(
168 1223145 &tracer->commit_buffer_[pos = ((base + i)
169 1223145 % tracer->buffer_size_)])
170 == 1)) {
171 1117887 string tmp;
172
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 1117887 tmp = StringifyTimeval(tracer->ring_buffer_[pos].time_stamp);
173
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 1117887 retval = tracer->WriteCsvFile(f, tmp);
174
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 1117887 retval |= fputc(',', f) - ',';
175
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 1117887 tmp = StringifyInt(tracer->ring_buffer_[pos].code);
176
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 1117887 retval = tracer->WriteCsvFile(f, tmp);
177
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 1117887 retval |= fputc(',', f) - ',';
178
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 1117887 retval |= tracer->WriteCsvFile(f,
179
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 2235774 tracer->ring_buffer_[pos].path.ToString());
180
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 1117887 retval |= fputc(',', f) - ',';
181
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 1117887 retval |= tracer->WriteCsvFile(f, tracer->ring_buffer_[pos].msg);
182
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 1117887 retval |= (fputc(13, f) - 13) | (fputc(10, f) - 10);
183
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 1117887 assert(retval == 0);
184
185 1117887 atomic_dec32(&tracer->commit_buffer_[pos]);
186 1117887 ++i;
187 1117887 }
188
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 269556 retval = fflush(f);
189
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 269556 assert(retval == 0);
190 269556 atomic_xadd32(&tracer->flushed_, i);
191 269556 atomic_cas32(&tracer->flush_immediately_, 1, 0);
192
193 {
194 269556 const MutexLockGuard l(&tracer->sig_continue_trace_mutex_);
195 269556 retval = pthread_cond_broadcast(&tracer->sig_continue_trace_);
196
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 269556 assert(retval == 0);
197 269556 }
198 } while (
199 269556 (atomic_read32(&tracer->terminate_flush_thread_) == 0)
200
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 269556 || (atomic_read32(&tracer->flushed_) < atomic_read32(&tracer->seq_no_)));
201
202
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 42 retval = fclose(f);
203
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 42 assert(retval == 0);
204 42 return NULL;
205 42 }
206
207
208 45 void Tracer::Spawn() {
209
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 45 if (active_) {
210 42 const int retval = pthread_create(&thread_flush_, NULL, MainFlush, this);
211
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 42 assert(retval == 0);
212
213 42 spawned_ = true;
214
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 42 DoTrace(kEventStart, PathString("Tracer", 6), "Trace buffer created");
215 }
216 45 }
217
218
219 220 Tracer::Tracer()
220 220 : active_(false)
221 220 , spawned_(false)
222 220 , buffer_size_(0)
223 220 , flush_threshold_(0)
224 220 , ring_buffer_(NULL)
225 220 , commit_buffer_(NULL) {
226 220 memset(&thread_flush_, 0, sizeof(thread_flush_));
227 220 atomic_init32(&seq_no_);
228 220 atomic_init32(&flushed_);
229 220 atomic_init32(&terminate_flush_thread_);
230 220 atomic_init32(&flush_immediately_);
231 220 }
232
233
234 262 Tracer::~Tracer() {
235
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 220 if (!active_)
236 178 return;
237 int retval;
238
239
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 42 if (spawned_) {
240 42 DoTrace(kEventStop, PathString("Tracer", 6), "Destroying trace buffer...");
241
242 // Trigger flushing and wait for it
243 42 atomic_inc32(&terminate_flush_thread_);
244 {
245 42 const MutexLockGuard m(&sig_flush_mutex_);
246 42 retval = pthread_cond_signal(&sig_flush_);
247
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 42 assert(retval == 0);
248 42 }
249 42 retval = pthread_join(thread_flush_, NULL);
250
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 42 assert(retval == 0);
251 }
252
253 42 retval = pthread_cond_destroy(&sig_continue_trace_);
254 42 retval |= pthread_mutex_destroy(&sig_continue_trace_mutex_);
255 42 retval |= pthread_cond_destroy(&sig_flush_);
256 42 retval |= pthread_mutex_destroy(&sig_flush_mutex_);
257
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 42 assert(retval == 0);
258
259
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 12624 delete[] ring_buffer_;
260
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 42 delete[] commit_buffer_;
261
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 220 }
262
263
264 4471548 int Tracer::WriteCsvFile(FILE *fp, const string &field) {
265
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 4471548 if (fp == NULL)
266 ✗ return 0;
267
268 int retval;
269
270
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 4471548 if ((retval = fputc('"', fp)) != '"')
271 ✗ return retval;
272
273
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 68940012 for (unsigned i = 0, l = field.length(); i < l; ++i) {
274
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 64468464 if (field[i] == '"') {
275
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 783000 if ((retval = fputc('"', fp)) != '"')
276 ✗ return retval;
277 }
278
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 64468464 if ((retval = fputc(field[i], fp)) != field[i])
279 ✗ return retval;
280 }
281
282
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 4471548 if ((retval = fputc('"', fp)) != '"')
283 ✗ return retval;
284
285 4471548 return 0;
286 }
287