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