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 "git-compat-util.h"
  25 #include "abspath.h"
  26 #include "environment.h"
  27 #include "quote.h"
  28 #include "setup.h"
  29 #include "trace.h"
  30 #include "wrapper.h"
  31
  32 struct trace_key trace_default_key = { "GIT_TRACE", 0, 0, 0 };
  33 struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
  34 struct trace_key trace_setup_key = TRACE_KEY_INIT(SETUP);
  35
  36 /* Get a trace file descriptor from "key" env variable. */
  37 static int get_trace_fd(struct trace_key *key, const char *override_envvar)
  38 {
  39         const char *trace;
  40
  41         /* don't open twice */
  42         if (key->initialized)
  43                 return key->fd;
  44
  45         trace = override_envvar ? override_envvar : getenv(key->key);
  46
  47         if (!trace || !strcmp(trace, "") ||
  48             !strcmp(trace, "0") || !strcasecmp(trace, "false"))
  49                 key->fd = 0;
  50         else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
  51                 key->fd = STDERR_FILENO;
  52         else if (strlen(trace) == 1 && isdigit(*trace))
  53                 key->fd = atoi(trace);
  54         else if (is_absolute_path(trace)) {
  55                 int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
  56                 if (fd == -1) {
  57                         warning("could not open '%s' for tracing: %s",
  58                                 trace, strerror(errno));
  59                         trace_disable(key);
  60                 } else {
  61                         key->fd = fd;
  62                         key->need_close = 1;
  63                 }
  64         } else {
  65                 warning("unknown trace value for '%s': %s\n"
  66                         "         If you want to trace into a file, then please set %s\n"
  67                         "         to an absolute pathname (starting with /)",
  68                         key->key, trace, key->key);
  69                 trace_disable(key);
  70         }
  71
  72         key->initialized = 1;
  73         return key->fd;
  74 }
  75
  76 void trace_override_envvar(struct trace_key *key, const char *value)
  77 {
  78         trace_disable(key);
  79         key->initialized = 0;
  80
  81         /*
  82          * Invoke get_trace_fd() to initialize key using the given value
  83          * instead of the value of the environment variable.
  84          */
  85         get_trace_fd(key, value);
  86 }
  87
  88 void trace_disable(struct trace_key *key)
  89 {
  90         if (key->need_close)
  91                 close(key->fd);
  92         key->fd = 0;
  93         key->initialized = 1;
  94         key->need_close = 0;
  95 }
  96
  97 static int prepare_trace_line(const char *file, int line,
  98                               struct trace_key *key, struct strbuf *buf)
  99 {
 100         static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
 101         struct timeval tv;
 102         struct tm tm;
 103         time_t secs;
 104
 105         if (!trace_want(key))
 106                 return 0;
 107
 108         /* unit tests may want to disable additional trace output */
 109         if (trace_want(&trace_bare))
 110                 return 1;
 111
 112         /* print current timestamp */
 113         gettimeofday(&tv, NULL);
 114         secs = tv.tv_sec;
 115         localtime_r(&secs, &tm);
 116         strbuf_addf(buf, "%02d:%02d:%02d.%06ld %s:%d", tm.tm_hour, tm.tm_min,
 117                     tm.tm_sec, (long) tv.tv_usec, file, line);
 118         /* align trace output (column 40 catches most files names in git) */
 119         while (buf->len < 40)
 120                 strbuf_addch(buf, ' ');
 121
 122         return 1;
 123 }
 124
 125 static void trace_write(struct trace_key *key, const void *buf, unsigned len)
 126 {
 127         if (write_in_full(get_trace_fd(key, NULL), buf, len) < 0) {
 128                 warning("unable to write trace for %s: %s",
 129                         key->key, strerror(errno));
 130                 trace_disable(key);
 131         }
 132 }
 133
 134 void trace_verbatim(struct trace_key *key, const void *buf, unsigned len)
 135 {
 136         if (!trace_want(key))
 137                 return;
 138         trace_write(key, buf, len);
 139 }
 140
 141 static void print_trace_line(struct trace_key *key, struct strbuf *buf)
 142 {
 143         strbuf_complete_line(buf);
 144         trace_write(key, buf->buf, buf->len);
 145 }
 146
 147 static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
 148                              const char *format, va_list ap)
 149 {
 150         struct strbuf buf = STRBUF_INIT;
 151
 152         if (!prepare_trace_line(file, line, key, &buf))
 153                 return;
 154
 155         strbuf_vaddf(&buf, format, ap);
 156         print_trace_line(key, &buf);
 157         strbuf_release(&buf);
 158 }
 159
 160 static void trace_argv_vprintf_fl(const char *file, int line,
 161                                   const char **argv, const char *format,
 162                                   va_list ap)
 163 {
 164         struct strbuf buf = STRBUF_INIT;
 165
 166         if (!prepare_trace_line(file, line, &trace_default_key, &buf))
 167                 return;
 168
 169         strbuf_vaddf(&buf, format, ap);
 170
 171         sq_quote_argv_pretty(&buf, argv);
 172         print_trace_line(&trace_default_key, &buf);
 173         strbuf_release(&buf);
 174 }
 175
 176 void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
 177                      const struct strbuf *data)
 178 {
 179         struct strbuf buf = STRBUF_INIT;
 180
 181         if (!prepare_trace_line(file, line, key, &buf))
 182                 return;
 183
 184         strbuf_addbuf(&buf, data);
 185         print_trace_line(key, &buf);
 186         strbuf_release(&buf);
 187 }
 188
 189 static uint64_t perf_start_times[10];
 190 static int perf_indent;
 191
 192 uint64_t trace_performance_enter(void)
 193 {
 194         uint64_t now;
 195
 196         if (!trace_want(&trace_perf_key))
 197                 return 0;
 198
 199         now = getnanotime();
 200         perf_start_times[perf_indent] = now;
 201         if (perf_indent + 1 < ARRAY_SIZE(perf_start_times))
 202                 perf_indent++;
 203         else
 204                 BUG("Too deep indentation");
 205         return now;
 206 }
 207
 208 static void trace_performance_vprintf_fl(const char *file, int line,
 209                                          uint64_t nanos, const char *format,
 210                                          va_list ap)
 211 {
 212         static const char space[] = "          ";
 213         struct strbuf buf = STRBUF_INIT;
 214
 215         if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
 216                 return;
 217
 218         strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);
 219
 220         if (format && *format) {
 221                 if (perf_indent >= strlen(space))
 222                         BUG("Too deep indentation");
 223
 224                 strbuf_addf(&buf, ":%.*s ", perf_indent, space);
 225                 strbuf_vaddf(&buf, format, ap);
 226         }
 227
 228         print_trace_line(&trace_perf_key, &buf);
 229         strbuf_release(&buf);
 230 }
 231
 232 void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
 233                          const char *format, ...)
 234 {
 235         va_list ap;
 236         va_start(ap, format);
 237         trace_vprintf_fl(file, line, key, format, ap);
 238         va_end(ap);
 239 }
 240
 241 void trace_argv_printf_fl(const char *file, int line, const char **argv,
 242                           const char *format, ...)
 243 {
 244         va_list ap;
 245         va_start(ap, format);
 246         trace_argv_vprintf_fl(file, line, argv, format, ap);
 247         va_end(ap);
 248 }
 249
 250 void trace_performance_fl(const char *file, int line, uint64_t nanos,
 251                               const char *format, ...)
 252 {
 253         va_list ap;
 254         va_start(ap, format);
 255         trace_performance_vprintf_fl(file, line, nanos, format, ap);
 256         va_end(ap);
 257 }
 258
 259 void trace_performance_leave_fl(const char *file, int line,
 260                                 uint64_t nanos, const char *format, ...)
 261 {
 262         va_list ap;
 263         uint64_t since;
 264
 265         if (perf_indent)
 266                 perf_indent--;
 267
 268         if (!format) /* Allow callers to leave without tracing anything */
 269                 return;
 270
 271         since = perf_start_times[perf_indent];
 272         va_start(ap, format);
 273         trace_performance_vprintf_fl(file, line, nanos - since, format, ap);
 274         va_end(ap);
 275 }
 276
 277 static const char *quote_crnl(const char *path)
 278 {
 279         static struct strbuf new_path = STRBUF_INIT;
 280
 281         if (!path)
 282                 return NULL;
 283
 284         strbuf_reset(&new_path);
 285
 286         while (*path) {
 287                 switch (*path) {
 288                 case '\\': strbuf_addstr(&new_path, "\\\\"); break;
 289                 case '\n': strbuf_addstr(&new_path, "\\n"); break;
 290                 case '\r': strbuf_addstr(&new_path, "\\r"); break;
 291                 default:
 292                         strbuf_addch(&new_path, *path);
 293                 }
 294                 path++;
 295         }
 296         return new_path.buf;
 297 }
 298
 299 void trace_repo_setup(void)
 300 {
 301         const char *git_work_tree, *prefix = startup_info->prefix;
 302         char *cwd;
 303
 304         if (!trace_want(&trace_setup_key))
 305                 return;
 306
 307         cwd = xgetcwd();
 308
 309         if (!(git_work_tree = get_git_work_tree()))
 310                 git_work_tree = "(null)";
 311
 312         if (!startup_info->prefix)
 313                 prefix = "(null)";
 314
 315         trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
 316         trace_printf_key(&trace_setup_key, "setup: git_common_dir: %s\n", quote_crnl(get_git_common_dir()));
 317         trace_printf_key(&trace_setup_key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
 318         trace_printf_key(&trace_setup_key, "setup: cwd: %s\n", quote_crnl(cwd));
 319         trace_printf_key(&trace_setup_key, "setup: prefix: %s\n", quote_crnl(prefix));
 320
 321         free(cwd);
 322 }
 323
 324 int trace_want(struct trace_key *key)
 325 {
 326         return !!get_trace_fd(key, NULL);
 327 }
 328
 329 #if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC)
 330
 331 static inline uint64_t highres_nanos(void)
 332 {
 333         struct timespec ts;
 334         if (clock_gettime(CLOCK_MONOTONIC, &ts))
 335                 return 0;
 336         return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
 337 }
 338
 339 #elif defined (GIT_WINDOWS_NATIVE)
 340
 341 static inline uint64_t highres_nanos(void)
 342 {
 343         static uint64_t high_ns, scaled_low_ns;
 344         static int scale;
 345         LARGE_INTEGER cnt;
 346
 347         if (!scale) {
 348                 if (!QueryPerformanceFrequency(&cnt))
 349                         return 0;
 350
 351                 /* high_ns = number of ns per cnt.HighPart */
 352                 high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;
 353
 354                 /*
 355                  * Number of ns per cnt.LowPart is 10^9 / frequency (or
 356                  * high_ns >> 32). For maximum precision, we scale this factor
 357                  * so that it just fits within 32 bit (i.e. won't overflow if
 358                  * multiplied with cnt.LowPart).
 359                  */
 360                 scaled_low_ns = high_ns;
 361                 scale = 32;
 362                 while (scaled_low_ns >= 0x100000000LL) {
 363                         scaled_low_ns >>= 1;
 364                         scale--;
 365                 }
 366         }
 367
 368         /* if QPF worked on initialization, we expect QPC to work as well */
 369         QueryPerformanceCounter(&cnt);
 370
 371         return (high_ns * cnt.HighPart) +
 372                ((scaled_low_ns * cnt.LowPart) >> scale);
 373 }
 374
 375 #else
 376 # define highres_nanos() 0
 377 #endif
 378
 379 static inline uint64_t gettimeofday_nanos(void)
 380 {
 381         struct timeval tv;
 382         gettimeofday(&tv, NULL);
 383         return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
 384 }
 385
 386 /*
 387  * Returns nanoseconds since the epoch (01/01/1970), for performance tracing
 388  * (i.e. favoring high precision over wall clock time accuracy).
 389  */
 390 uint64_t getnanotime(void)
 391 {
 392         static uint64_t offset;
 393         if (offset > 1) {
 394                 /* initialization succeeded, return offset + high res time */
 395                 return offset + highres_nanos();
 396         } else if (offset == 1) {
 397                 /* initialization failed, fall back to gettimeofday */
 398                 return gettimeofday_nanos();
 399         } else {
 400                 /* initialize offset if high resolution timer works */
 401                 uint64_t now = gettimeofday_nanos();
 402                 uint64_t highres = highres_nanos();
 403                 if (highres)
 404                         offset = now - highres;
 405                 else
 406                         offset = 1;
 407                 return now;
 408         }
 409 }
 410
 411 static struct strbuf command_line = STRBUF_INIT;
 412
 413 static void print_command_performance_atexit(void)
 414 {
 415         trace_performance_leave("git command:%s", command_line.buf);
 416 }
 417
 418 void trace_command_performance(const char **argv)
 419 {
 420         if (!trace_want(&trace_perf_key))
 421                 return;
 422
 423         if (!command_line.len)
 424                 atexit(print_command_performance_atexit);
 425
 426         strbuf_reset(&command_line);
 427         sq_quote_argv_pretty(&command_line, argv);
 428         trace_performance_enter();
 429 }