trace: add trace_performance facility to debug performance issues
[git/git.git] / trace.c
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1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) 2000-2002 Michael R. Elkins <me@mutt.org>
5 * Copyright (C) 2002-2004 Oswald Buddenhagen <ossi@users.sf.net>
6 * Copyright (C) 2004 Theodore Y. Ts'o <tytso@mit.edu>
7 * Copyright (C) 2006 Mike McCormack
8 * Copyright (C) 2006 Christian Couder
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 */
24
25#include "cache.h"
26#include "quote.h"
27
06796607 28/* Get a trace file descriptor from "key" env variable. */
6aa30857 29static int get_trace_fd(struct trace_key *key)
6ce4e61f 30{
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31 static struct trace_key trace_default = { "GIT_TRACE" };
32 const char *trace;
33
34 /* use default "GIT_TRACE" if NULL */
35 if (!key)
36 key = &trace_default;
37
38 /* don't open twice */
39 if (key->initialized)
40 return key->fd;
41
42 trace = getenv(key->key);
6ce4e61f 43
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44 if (!trace || !strcmp(trace, "") ||
45 !strcmp(trace, "0") || !strcasecmp(trace, "false"))
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46 key->fd = 0;
47 else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
48 key->fd = STDERR_FILENO;
49 else if (strlen(trace) == 1 && isdigit(*trace))
50 key->fd = atoi(trace);
51 else if (is_absolute_path(trace)) {
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52 int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
53 if (fd == -1) {
54 fprintf(stderr,
55 "Could not open '%s' for tracing: %s\n"
56 "Defaulting to tracing on stderr...\n",
57 trace, strerror(errno));
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58 key->fd = STDERR_FILENO;
59 } else {
60 key->fd = fd;
61 key->need_close = 1;
6ce4e61f 62 }
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63 } else {
64 fprintf(stderr, "What does '%s' for %s mean?\n"
65 "If you want to trace into a file, then please set "
66 "%s to an absolute pathname (starting with /).\n"
67 "Defaulting to tracing on stderr...\n",
68 trace, key->key, key->key);
69 key->fd = STDERR_FILENO;
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70 }
71
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72 key->initialized = 1;
73 return key->fd;
74}
6ce4e61f 75
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76void trace_disable(struct trace_key *key)
77{
78 if (key->need_close)
79 close(key->fd);
80 key->fd = 0;
81 key->initialized = 1;
82 key->need_close = 0;
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83}
84
85static const char err_msg[] = "Could not trace into fd given by "
86 "GIT_TRACE environment variable";
87
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88static int prepare_trace_line(const char *file, int line,
89 struct trace_key *key, struct strbuf *buf)
c69dfd24 90{
124647c4 91 static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
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92 struct timeval tv;
93 struct tm tm;
94 time_t secs;
124647c4 95
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96 if (!trace_want(key))
97 return 0;
98
99 set_try_to_free_routine(NULL); /* is never reset */
100
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101 /* unit tests may want to disable additional trace output */
102 if (trace_want(&trace_bare))
103 return 1;
104
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105 /* print current timestamp */
106 gettimeofday(&tv, NULL);
107 secs = tv.tv_sec;
108 localtime_r(&secs, &tm);
109 strbuf_addf(buf, "%02d:%02d:%02d.%06ld ", tm.tm_hour, tm.tm_min,
110 tm.tm_sec, (long) tv.tv_usec);
c69dfd24 111
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112#ifdef HAVE_VARIADIC_MACROS
113 /* print file:line */
114 strbuf_addf(buf, "%s:%d ", file, line);
115 /* align trace output (column 40 catches most files names in git) */
116 while (buf->len < 40)
117 strbuf_addch(buf, ' ');
118#endif
119
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120 return 1;
121}
122
123static void print_trace_line(struct trace_key *key, struct strbuf *buf)
124{
125 /* append newline if missing */
126 if (buf->len && buf->buf[buf->len - 1] != '\n')
127 strbuf_addch(buf, '\n');
128
129 write_or_whine_pipe(get_trace_fd(key), buf->buf, buf->len, err_msg);
130 strbuf_release(buf);
131}
132
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133static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
134 const char *format, va_list ap)
6ce4e61f 135{
ebeb6090 136 struct strbuf buf = STRBUF_INIT;
6ce4e61f 137
e05bed96 138 if (!prepare_trace_line(file, line, key, &buf))
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139 return;
140
4a3b0b25 141 strbuf_vaddf(&buf, format, ap);
c69dfd24 142 print_trace_line(key, &buf);
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143}
144
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145static void trace_argv_vprintf_fl(const char *file, int line,
146 const char **argv, const char *format,
147 va_list ap)
06796607 148{
66f66c59 149 struct strbuf buf = STRBUF_INIT;
06796607 150
e05bed96 151 if (!prepare_trace_line(file, line, NULL, &buf))
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152 return;
153
66f66c59 154 strbuf_vaddf(&buf, format, ap);
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155
156 sq_quote_argv(&buf, argv, 0);
157 print_trace_line(NULL, &buf);
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158}
159
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160void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
161 const struct strbuf *data)
94b3b374 162{
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163 struct strbuf buf = STRBUF_INIT;
164
e05bed96 165 if (!prepare_trace_line(file, line, key, &buf))
94b3b374
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166 return;
167
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168 strbuf_addbuf(&buf, data);
169 print_trace_line(key, &buf);
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170}
171
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172static struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
173
174static void trace_performance_vprintf_fl(const char *file, int line,
175 uint64_t nanos, const char *format,
176 va_list ap)
177{
178 struct strbuf buf = STRBUF_INIT;
179
180 if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
181 return;
182
183 strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);
184
185 if (format && *format) {
186 strbuf_addstr(&buf, ": ");
187 strbuf_vaddf(&buf, format, ap);
188 }
189
190 print_trace_line(&trace_perf_key, &buf);
191}
192
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193#ifndef HAVE_VARIADIC_MACROS
194
66f66c59 195void trace_printf(const char *format, ...)
6ce4e61f 196{
19247e55 197 va_list ap;
4a3b0b25 198 va_start(ap, format);
e05bed96 199 trace_vprintf_fl(NULL, 0, NULL, format, ap);
19247e55 200 va_end(ap);
66f66c59 201}
6ce4e61f 202
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203void trace_printf_key(struct trace_key *key, const char *format, ...)
204{
205 va_list ap;
206 va_start(ap, format);
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207 trace_vprintf_fl(NULL, 0, key, format, ap);
208 va_end(ap);
209}
210
211void trace_argv_printf(const char **argv, const char *format, ...)
212{
213 va_list ap;
214 va_start(ap, format);
215 trace_argv_vprintf_fl(NULL, 0, argv, format, ap);
66f66c59 216 va_end(ap);
6ce4e61f 217}
a9ca8a85 218
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219void trace_strbuf(const char *key, const struct strbuf *data)
220{
221 trace_strbuf_fl(NULL, 0, key, data);
222}
223
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224void trace_performance(uint64_t nanos, const char *format, ...)
225{
226 va_list ap;
227 va_start(ap, format);
228 trace_performance_vprintf_fl(NULL, 0, nanos, format, ap);
229 va_end(ap);
230}
231
232void trace_performance_since(uint64_t start, const char *format, ...)
233{
234 va_list ap;
235 va_start(ap, format);
236 trace_performance_vprintf_fl(NULL, 0, getnanotime() - start,
237 format, ap);
238 va_end(ap);
239}
240
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241#else
242
243void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
244 const char *format, ...)
245{
246 va_list ap;
247 va_start(ap, format);
248 trace_vprintf_fl(file, line, key, format, ap);
249 va_end(ap);
250}
251
252void trace_argv_printf_fl(const char *file, int line, const char **argv,
253 const char *format, ...)
254{
255 va_list ap;
256 va_start(ap, format);
257 trace_argv_vprintf_fl(file, line, argv, format, ap);
258 va_end(ap);
259}
260
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261void trace_performance_fl(const char *file, int line, uint64_t nanos,
262 const char *format, ...)
263{
264 va_list ap;
265 va_start(ap, format);
266 trace_performance_vprintf_fl(file, line, nanos, format, ap);
267 va_end(ap);
268}
269
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270#endif /* HAVE_VARIADIC_MACROS */
271
272
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273static const char *quote_crnl(const char *path)
274{
275 static char new_path[PATH_MAX];
276 const char *p2 = path;
277 char *p1 = new_path;
278
279 if (!path)
280 return NULL;
281
282 while (*p2) {
283 switch (*p2) {
284 case '\\': *p1++ = '\\'; *p1++ = '\\'; break;
285 case '\n': *p1++ = '\\'; *p1++ = 'n'; break;
286 case '\r': *p1++ = '\\'; *p1++ = 'r'; break;
287 default:
288 *p1++ = *p2;
289 }
290 p2++;
291 }
292 *p1 = '\0';
293 return new_path;
294}
295
296/* FIXME: move prefix to startup_info struct and get rid of this arg */
297void trace_repo_setup(const char *prefix)
298{
6aa30857 299 static struct trace_key key = TRACE_KEY_INIT(SETUP);
e83c267f 300 const char *git_work_tree;
a9ca8a85 301 char cwd[PATH_MAX];
a9ca8a85 302
6aa30857 303 if (!trace_want(&key))
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304 return;
305
306 if (!getcwd(cwd, PATH_MAX))
307 die("Unable to get current working directory");
308
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309 if (!(git_work_tree = get_git_work_tree()))
310 git_work_tree = "(null)";
311
312 if (!prefix)
313 prefix = "(null)";
314
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315 trace_printf_key(&key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
316 trace_printf_key(&key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
317 trace_printf_key(&key, "setup: cwd: %s\n", quote_crnl(cwd));
318 trace_printf_key(&key, "setup: prefix: %s\n", quote_crnl(prefix));
a9ca8a85 319}
39bc5e46 320
6aa30857 321int trace_want(struct trace_key *key)
39bc5e46 322{
6aa30857 323 return !!get_trace_fd(key);
39bc5e46 324}
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325
326#ifdef HAVE_CLOCK_GETTIME
327
328static inline uint64_t highres_nanos(void)
329{
330 struct timespec ts;
331 if (clock_gettime(CLOCK_MONOTONIC, &ts))
332 return 0;
333 return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
334}
335
336#elif defined (GIT_WINDOWS_NATIVE)
337
338static inline uint64_t highres_nanos(void)
339{
340 static uint64_t high_ns, scaled_low_ns;
341 static int scale;
342 LARGE_INTEGER cnt;
343
344 if (!scale) {
345 if (!QueryPerformanceFrequency(&cnt))
346 return 0;
347
348 /* high_ns = number of ns per cnt.HighPart */
349 high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;
350
351 /*
352 * Number of ns per cnt.LowPart is 10^9 / frequency (or
353 * high_ns >> 32). For maximum precision, we scale this factor
354 * so that it just fits within 32 bit (i.e. won't overflow if
355 * multiplied with cnt.LowPart).
356 */
357 scaled_low_ns = high_ns;
358 scale = 32;
359 while (scaled_low_ns >= 0x100000000LL) {
360 scaled_low_ns >>= 1;
361 scale--;
362 }
363 }
364
365 /* if QPF worked on initialization, we expect QPC to work as well */
366 QueryPerformanceCounter(&cnt);
367
368 return (high_ns * cnt.HighPart) +
369 ((scaled_low_ns * cnt.LowPart) >> scale);
370}
371
372#else
373# define highres_nanos() 0
374#endif
375
376static inline uint64_t gettimeofday_nanos(void)
377{
378 struct timeval tv;
379 gettimeofday(&tv, NULL);
380 return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
381}
382
383/*
384 * Returns nanoseconds since the epoch (01/01/1970), for performance tracing
385 * (i.e. favoring high precision over wall clock time accuracy).
386 */
387inline uint64_t getnanotime(void)
388{
389 static uint64_t offset;
390 if (offset > 1) {
391 /* initialization succeeded, return offset + high res time */
392 return offset + highres_nanos();
393 } else if (offset == 1) {
394 /* initialization failed, fall back to gettimeofday */
395 return gettimeofday_nanos();
396 } else {
397 /* initialize offset if high resolution timer works */
398 uint64_t now = gettimeofday_nanos();
399 uint64_t highres = highres_nanos();
400 if (highres)
401 offset = now - highres;
402 else
403 offset = 1;
404 return now;
405 }
406}