trace.c

   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, see <http://www.gnu.org/licenses/>.
  22  */
  23
  24 #include "cache.h"
  25 #include "abspath.h"
  26 #include "environment.h"
  27 #include "quote.h"
  28 #include "wrapper.h"
  29
  30 struct trace_key trace_default_key = { "GIT_TRACE", 0, 0, 0 };
  31 struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
  32 struct trace_key trace_setup_key = TRACE_KEY_INIT(SETUP);
  33
  34 /* Get a trace file descriptor from "key" env variable. */
  35 static int get_trace_fd(struct trace_key *key, const char *override_envvar)
  36 {
  37         const char *trace;
  38
  39         /* don't open twice */
  40         if (key->initialized)
  41                 return key->fd;
  42
  43         trace = override_envvar ? override_envvar : getenv(key->key);
  44
  45         if (!trace || !strcmp(trace, "") ||
  46             !strcmp(trace, "0") || !strcasecmp(trace, "false"))
  47                 key->fd = 0;
  48         else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
  49                 key->fd = STDERR_FILENO;
  50         else if (strlen(trace) == 1 && isdigit(*trace))
  51                 key->fd = atoi(trace);
  52         else if (is_absolute_path(trace)) {
  53                 int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
  54                 if (fd == -1) {
  55                         warning("could not open '%s' for tracing: %s",
  56                                 trace, strerror(errno));
  57                         trace_disable(key);
  58                 } else {
  59                         key->fd = fd;
  60                         key->need_close = 1;
  61                 }
  62         } else {
  63                 warning("unknown trace value for '%s': %s\n"
  64                         "         If you want to trace into a file, then please set %s\n"
  65                         "         to an absolute pathname (starting with /)",
  66                         key->key, trace, key->key);
  67                 trace_disable(key);
  68         }
  69
  70         key->initialized = 1;
  71         return key->fd;
  72 }
  73
  74 void trace_override_envvar(struct trace_key *key, const char *value)
  75 {
  76         trace_disable(key);
  77         key->initialized = 0;
  78
  79         /*
  80          * Invoke get_trace_fd() to initialize key using the given value
  81          * instead of the value of the environment variable.
  82          */
  83         get_trace_fd(key, value);
  84 }
  85
  86 void trace_disable(struct trace_key *key)
  87 {
  88         if (key->need_close)
  89                 close(key->fd);
  90         key->fd = 0;
  91         key->initialized = 1;
  92         key->need_close = 0;
  93 }
  94
  95 static int prepare_trace_line(const char *file, int line,
  96                               struct trace_key *key, struct strbuf *buf)
  97 {
  98         static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
  99         struct timeval tv;
 100         struct tm tm;
 101         time_t secs;
 102
 103         if (!trace_want(key))
 104                 return 0;
 105
 106         /* unit tests may want to disable additional trace output */
 107         if (trace_want(&trace_bare))
 108                 return 1;
 109
 110         /* print current timestamp */
 111         gettimeofday(&tv, NULL);
 112         secs = tv.tv_sec;
 113         localtime_r(&secs, &tm);
 114         strbuf_addf(buf, "%02d:%02d:%02d.%06ld %s:%d", tm.tm_hour, tm.tm_min,
 115                     tm.tm_sec, (long) tv.tv_usec, file, line);
 116         /* align trace output (column 40 catches most files names in git) */
 117         while (buf->len < 40)
 118                 strbuf_addch(buf, ' ');
 119
 120         return 1;
 121 }
 122
 123 static void trace_write(struct trace_key *key, const void *buf, unsigned len)
 124 {
 125         if (write_in_full(get_trace_fd(key, NULL), buf, len) < 0) {
 126                 warning("unable to write trace for %s: %s",
 127                         key->key, strerror(errno));
 128                 trace_disable(key);
 129         }
 130 }
 131
 132 void trace_verbatim(struct trace_key *key, const void *buf, unsigned len)
 133 {
 134         if (!trace_want(key))
 135                 return;
 136         trace_write(key, buf, len);
 137 }
 138
 139 static void print_trace_line(struct trace_key *key, struct strbuf *buf)
 140 {
 141         strbuf_complete_line(buf);
 142         trace_write(key, buf->buf, buf->len);
 143 }
 144
 145 static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
 146                              const char *format, va_list ap)
 147 {
 148         struct strbuf buf = STRBUF_INIT;
 149
 150         if (!prepare_trace_line(file, line, key, &buf))
 151                 return;
 152
 153         strbuf_vaddf(&buf, format, ap);
 154         print_trace_line(key, &buf);
 155         strbuf_release(&buf);
 156 }
 157
 158 static void trace_argv_vprintf_fl(const char *file, int line,
 159                                   const char **argv, const char *format,
 160                                   va_list ap)
 161 {
 162         struct strbuf buf = STRBUF_INIT;
 163
 164         if (!prepare_trace_line(file, line, &trace_default_key, &buf))
 165                 return;
 166
 167         strbuf_vaddf(&buf, format, ap);
 168
 169         sq_quote_argv_pretty(&buf, argv);
 170         print_trace_line(&trace_default_key, &buf);
 171         strbuf_release(&buf);
 172 }
 173
 174 void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
 175                      const struct strbuf *data)
 176 {
 177         struct strbuf buf = STRBUF_INIT;
 178
 179         if (!prepare_trace_line(file, line, key, &buf))
 180                 return;
 181
 182         strbuf_addbuf(&buf, data);
 183         print_trace_line(key, &buf);
 184         strbuf_release(&buf);
 185 }
 186
 187 static uint64_t perf_start_times[10];
 188 static int perf_indent;
 189
 190 uint64_t trace_performance_enter(void)
 191 {
 192         uint64_t now;
 193
 194         if (!trace_want(&trace_perf_key))
 195                 return 0;
 196
 197         now = getnanotime();
 198         perf_start_times[perf_indent] = now;
 199         if (perf_indent + 1 < ARRAY_SIZE(perf_start_times))
 200                 perf_indent++;
 201         else
 202                 BUG("Too deep indentation");
 203         return now;
 204 }
 205
 206 static void trace_performance_vprintf_fl(const char *file, int line,
 207                                          uint64_t nanos, const char *format,
 208                                          va_list ap)
 209 {
 210         static const char space[] = "          ";
 211         struct strbuf buf = STRBUF_INIT;
 212
 213         if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
 214                 return;
 215
 216         strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);
 217
 218         if (format && *format) {
 219                 if (perf_indent >= strlen(space))
 220                         BUG("Too deep indentation");
 221
 222                 strbuf_addf(&buf, ":%.*s ", perf_indent, space);
 223                 strbuf_vaddf(&buf, format, ap);
 224         }
 225
 226         print_trace_line(&trace_perf_key, &buf);
 227         strbuf_release(&buf);
 228 }
 229
 230 void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
 231                          const char *format, ...)
 232 {
 233         va_list ap;
 234         va_start(ap, format);
 235         trace_vprintf_fl(file, line, key, format, ap);
 236         va_end(ap);
 237 }
 238
 239 void trace_argv_printf_fl(const char *file, int line, const char **argv,
 240                           const char *format, ...)
 241 {
 242         va_list ap;
 243         va_start(ap, format);
 244         trace_argv_vprintf_fl(file, line, argv, format, ap);
 245         va_end(ap);
 246 }
 247
 248 void trace_performance_fl(const char *file, int line, uint64_t nanos,
 249                               const char *format, ...)
 250 {
 251         va_list ap;
 252         va_start(ap, format);
 253         trace_performance_vprintf_fl(file, line, nanos, format, ap);
 254         va_end(ap);
 255 }
 256
 257 void trace_performance_leave_fl(const char *file, int line,
 258                                 uint64_t nanos, const char *format, ...)
 259 {
 260         va_list ap;
 261         uint64_t since;
 262
 263         if (perf_indent)
 264                 perf_indent--;
 265
 266         if (!format) /* Allow callers to leave without tracing anything */
 267                 return;
 268
 269         since = perf_start_times[perf_indent];
 270         va_start(ap, format);
 271         trace_performance_vprintf_fl(file, line, nanos - since, format, ap);
 272         va_end(ap);
 273 }
 274
 275 static const char *quote_crnl(const char *path)
 276 {
 277         static struct strbuf new_path = STRBUF_INIT;
 278
 279         if (!path)
 280                 return NULL;
 281
 282         strbuf_reset(&new_path);
 283
 284         while (*path) {
 285                 switch (*path) {
 286                 case '\\': strbuf_addstr(&new_path, "\\\\"); break;
 287                 case '\n': strbuf_addstr(&new_path, "\\n"); break;
 288                 case '\r': strbuf_addstr(&new_path, "\\r"); break;
 289                 default:
 290                         strbuf_addch(&new_path, *path);
 291                 }
 292                 path++;
 293         }
 294         return new_path.buf;
 295 }
 296
 297 void trace_repo_setup(void)
 298 {
 299         const char *git_work_tree, *prefix = startup_info->prefix;
 300         char *cwd;
 301
 302         if (!trace_want(&trace_setup_key))
 303                 return;
 304
 305         cwd = xgetcwd();
 306
 307         if (!(git_work_tree = get_git_work_tree()))
 308                 git_work_tree = "(null)";
 309
 310         if (!startup_info->prefix)
 311                 prefix = "(null)";
 312
 313         trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
 314         trace_printf_key(&trace_setup_key, "setup: git_common_dir: %s\n", quote_crnl(get_git_common_dir()));
 315         trace_printf_key(&trace_setup_key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
 316         trace_printf_key(&trace_setup_key, "setup: cwd: %s\n", quote_crnl(cwd));
 317         trace_printf_key(&trace_setup_key, "setup: prefix: %s\n", quote_crnl(prefix));
 318
 319         free(cwd);
 320 }
 321
 322 int trace_want(struct trace_key *key)
 323 {
 324         return !!get_trace_fd(key, NULL);
 325 }
 326
 327 #if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC)
 328
 329 static inline uint64_t highres_nanos(void)
 330 {
 331         struct timespec ts;
 332         if (clock_gettime(CLOCK_MONOTONIC, &ts))
 333                 return 0;
 334         return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
 335 }
 336
 337 #elif defined (GIT_WINDOWS_NATIVE)
 338
 339 static inline uint64_t highres_nanos(void)
 340 {
 341         static uint64_t high_ns, scaled_low_ns;
 342         static int scale;
 343         LARGE_INTEGER cnt;
 344
 345         if (!scale) {
 346                 if (!QueryPerformanceFrequency(&cnt))
 347                         return 0;
 348
 349                 /* high_ns = number of ns per cnt.HighPart */
 350                 high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;
 351
 352                 /*
 353                  * Number of ns per cnt.LowPart is 10^9 / frequency (or
 354                  * high_ns >> 32). For maximum precision, we scale this factor
 355                  * so that it just fits within 32 bit (i.e. won't overflow if
 356                  * multiplied with cnt.LowPart).
 357                  */
 358                 scaled_low_ns = high_ns;
 359                 scale = 32;
 360                 while (scaled_low_ns >= 0x100000000LL) {
 361                         scaled_low_ns >>= 1;
 362                         scale--;
 363                 }
 364         }
 365
 366         /* if QPF worked on initialization, we expect QPC to work as well */
 367         QueryPerformanceCounter(&cnt);
 368
 369         return (high_ns * cnt.HighPart) +
 370                ((scaled_low_ns * cnt.LowPart) >> scale);
 371 }
 372
 373 #else
 374 # define highres_nanos() 0
 375 #endif
 376
 377 static inline uint64_t gettimeofday_nanos(void)
 378 {
 379         struct timeval tv;
 380         gettimeofday(&tv, NULL);
 381         return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
 382 }
 383
 384 /*
 385  * Returns nanoseconds since the epoch (01/01/1970), for performance tracing
 386  * (i.e. favoring high precision over wall clock time accuracy).
 387  */
 388 uint64_t getnanotime(void)
 389 {
 390         static uint64_t offset;
 391         if (offset > 1) {
 392                 /* initialization succeeded, return offset + high res time */
 393                 return offset + highres_nanos();
 394         } else if (offset == 1) {
 395                 /* initialization failed, fall back to gettimeofday */
 396                 return gettimeofday_nanos();
 397         } else {
 398                 /* initialize offset if high resolution timer works */
 399                 uint64_t now = gettimeofday_nanos();
 400                 uint64_t highres = highres_nanos();
 401                 if (highres)
 402                         offset = now - highres;
 403                 else
 404                         offset = 1;
 405                 return now;
 406         }
 407 }
 408
 409 static struct strbuf command_line = STRBUF_INIT;
 410
 411 static void print_command_performance_atexit(void)
 412 {
 413         trace_performance_leave("git command:%s", command_line.buf);
 414 }
 415
 416 void trace_command_performance(const char **argv)
 417 {
 418         if (!trace_want(&trace_perf_key))
 419                 return;
 420
 421         if (!command_line.len)
 422                 atexit(print_command_performance_atexit);
 423
 424         strbuf_reset(&command_line);
 425         sq_quote_argv_pretty(&command_line, argv);
 426         trace_performance_enter();
 427 }