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 <https://www.gnu.org/licenses/>.
  22  */
  23
  24 #define USE_THE_REPOSITORY_VARIABLE
  25
  26 #include "git-compat-util.h"
  27 #include "abspath.h"
  28 #include "repository.h"
  29 #include "quote.h"
  30 #include "setup.h"
  31 #include "trace.h"
  32
  33 struct trace_key trace_default_key = { "GIT_TRACE", 0, 0, 0 };
  34 struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
  35 struct trace_key trace_setup_key = TRACE_KEY_INIT(SETUP);
  36
  37 /* Get a trace file descriptor from "key" env variable. */
  38 static int get_trace_fd(struct trace_key *key, const char *override_envvar)
  39 {
  40         const char *trace;
  41
  42         /* don't open twice */
  43         if (key->initialized)
  44                 return key->fd;
  45
  46         trace = override_envvar ? override_envvar : getenv(key->key);
  47
  48         if (!trace || !strcmp(trace, "") ||
  49             !strcmp(trace, "0") || !strcasecmp(trace, "false"))
  50                 key->fd = 0;
  51         else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
  52                 key->fd = STDERR_FILENO;
  53         else if (strlen(trace) == 1 && isdigit(*trace))
  54                 key->fd = atoi(trace);
  55         else if (is_absolute_path(trace)) {
  56                 int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
  57                 if (fd == -1) {
  58                         warning("could not open '%s' for tracing: %s",
  59                                 trace, strerror(errno));
  60                         trace_disable(key);
  61                 } else {
  62                         key->fd = fd;
  63                         key->need_close = 1;
  64                 }
  65         } else {
  66                 warning("unknown trace value for '%s': %s\n"
  67                         "         If you want to trace into a file, then please set %s\n"
  68                         "         to an absolute pathname (starting with /)",
  69                         key->key, trace, key->key);
  70                 trace_disable(key);
  71         }
  72
  73         key->initialized = 1;
  74         return key->fd;
  75 }
  76
  77 void trace_override_envvar(struct trace_key *key, const char *value)
  78 {
  79         trace_disable(key);
  80         key->initialized = 0;
  81
  82         /*
  83          * Invoke get_trace_fd() to initialize key using the given value
  84          * instead of the value of the environment variable.
  85          */
  86         get_trace_fd(key, value);
  87 }
  88
  89 void trace_disable(struct trace_key *key)
  90 {
  91         if (key->need_close)
  92                 close(key->fd);
  93         key->fd = 0;
  94         key->initialized = 1;
  95         key->need_close = 0;
  96 }
  97
  98 static int prepare_trace_line(const char *file, int line,
  99                               struct trace_key *key, struct strbuf *buf)
 100 {
 101         static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
 102         struct timeval tv;
 103         struct tm tm;
 104         time_t secs;
 105
 106         if (!trace_want(key))
 107                 return 0;
 108
 109         /* unit tests may want to disable additional trace output */
 110         if (trace_want(&trace_bare))
 111                 return 1;
 112
 113         /* print current timestamp */
 114         gettimeofday(&tv, NULL);
 115         secs = tv.tv_sec;
 116         localtime_r(&secs, &tm);
 117         strbuf_addf(buf, "%02d:%02d:%02d.%06ld %s:%d", tm.tm_hour, tm.tm_min,
 118                     tm.tm_sec, (long) tv.tv_usec, file, line);
 119         /* align trace output (column 40 catches most files names in git) */
 120         while (buf->len < 40)
 121                 strbuf_addch(buf, ' ');
 122
 123         return 1;
 124 }
 125
 126 static void trace_write(struct trace_key *key, const void *buf, unsigned len)
 127 {
 128         if (write_in_full(get_trace_fd(key, NULL), buf, len) < 0) {
 129                 warning("unable to write trace for %s: %s",
 130                         key->key, strerror(errno));
 131                 trace_disable(key);
 132         }
 133 }
 134
 135 void trace_verbatim(struct trace_key *key, const void *buf, unsigned len)
 136 {
 137         if (!trace_want(key))
 138                 return;
 139         trace_write(key, buf, len);
 140 }
 141
 142 static void print_trace_line(struct trace_key *key, struct strbuf *buf)
 143 {
 144         strbuf_complete_line(buf);
 145         trace_write(key, buf->buf, buf->len);
 146 }
 147
 148 static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
 149                              const char *format, va_list ap)
 150 {
 151         struct strbuf buf = STRBUF_INIT;
 152
 153         if (!prepare_trace_line(file, line, key, &buf))
 154                 return;
 155
 156         strbuf_vaddf(&buf, format, ap);
 157         print_trace_line(key, &buf);
 158         strbuf_release(&buf);
 159 }
 160
 161 static void trace_argv_vprintf_fl(const char *file, int line,
 162                                   const char **argv, const char *format,
 163                                   va_list ap)
 164 {
 165         struct strbuf buf = STRBUF_INIT;
 166
 167         if (!prepare_trace_line(file, line, &trace_default_key, &buf))
 168                 return;
 169
 170         strbuf_vaddf(&buf, format, ap);
 171
 172         sq_quote_argv_pretty(&buf, argv);
 173         print_trace_line(&trace_default_key, &buf);
 174         strbuf_release(&buf);
 175 }
 176
 177 void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
 178                      const struct strbuf *data)
 179 {
 180         struct strbuf buf = STRBUF_INIT;
 181
 182         if (!prepare_trace_line(file, line, key, &buf))
 183                 return;
 184
 185         strbuf_addbuf(&buf, data);
 186         print_trace_line(key, &buf);
 187         strbuf_release(&buf);
 188 }
 189
 190 static uint64_t perf_start_times[10];
 191 static int perf_indent;
 192
 193 uint64_t trace_performance_enter(void)
 194 {
 195         uint64_t now;
 196
 197         if (!trace_want(&trace_perf_key))
 198                 return 0;
 199
 200         now = getnanotime();
 201         perf_start_times[perf_indent] = now;
 202         if (perf_indent + 1 < ARRAY_SIZE(perf_start_times))
 203                 perf_indent++;
 204         else
 205                 BUG("Too deep indentation");
 206         return now;
 207 }
 208
 209 static void trace_performance_vprintf_fl(const char *file, int line,
 210                                          uint64_t nanos, const char *format,
 211                                          va_list ap)
 212 {
 213         static const char space[] = "          ";
 214         struct strbuf buf = STRBUF_INIT;
 215
 216         if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
 217                 return;
 218
 219         strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);
 220
 221         if (format && *format) {
 222                 if (perf_indent >= strlen(space))
 223                         BUG("Too deep indentation");
 224
 225                 strbuf_addf(&buf, ":%.*s ", perf_indent, space);
 226                 strbuf_vaddf(&buf, format, ap);
 227         }
 228
 229         print_trace_line(&trace_perf_key, &buf);
 230         strbuf_release(&buf);
 231 }
 232
 233 void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
 234                          const char *format, ...)
 235 {
 236         va_list ap;
 237         va_start(ap, format);
 238         trace_vprintf_fl(file, line, key, format, ap);
 239         va_end(ap);
 240 }
 241
 242 void trace_argv_printf_fl(const char *file, int line, const char **argv,
 243                           const char *format, ...)
 244 {
 245         va_list ap;
 246         va_start(ap, format);
 247         trace_argv_vprintf_fl(file, line, argv, format, ap);
 248         va_end(ap);
 249 }
 250
 251 void trace_performance_fl(const char *file, int line, uint64_t nanos,
 252                               const char *format, ...)
 253 {
 254         va_list ap;
 255         va_start(ap, format);
 256         trace_performance_vprintf_fl(file, line, nanos, format, ap);
 257         va_end(ap);
 258 }
 259
 260 void trace_performance_leave_fl(const char *file, int line,
 261                                 uint64_t nanos, const char *format, ...)
 262 {
 263         va_list ap;
 264         uint64_t since;
 265
 266         if (perf_indent)
 267                 perf_indent--;
 268
 269         if (!format) /* Allow callers to leave without tracing anything */
 270                 return;
 271
 272         since = perf_start_times[perf_indent];
 273         va_start(ap, format);
 274         trace_performance_vprintf_fl(file, line, nanos - since, format, ap);
 275         va_end(ap);
 276 }
 277
 278 static const char *quote_crnl(const char *path)
 279 {
 280         static struct strbuf new_path = STRBUF_INIT;
 281
 282         if (!path)
 283                 return NULL;
 284
 285         strbuf_reset(&new_path);
 286
 287         while (*path) {
 288                 switch (*path) {
 289                 case '\\': strbuf_addstr(&new_path, "\\\\"); break;
 290                 case '\n': strbuf_addstr(&new_path, "\\n"); break;
 291                 case '\r': strbuf_addstr(&new_path, "\\r"); break;
 292                 default:
 293                         strbuf_addch(&new_path, *path);
 294                 }
 295                 path++;
 296         }
 297         return new_path.buf;
 298 }
 299
 300 void trace_repo_setup(void)
 301 {
 302         const char *git_work_tree, *prefix = startup_info->prefix;
 303         char *cwd;
 304
 305         if (!trace_want(&trace_setup_key))
 306                 return;
 307
 308         cwd = xgetcwd();
 309
 310         if (!(git_work_tree = repo_get_work_tree(the_repository)))
 311                 git_work_tree = "(null)";
 312
 313         if (!startup_info->prefix)
 314                 prefix = "(null)";
 315
 316         trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(repo_get_git_dir(the_repository)));
 317         trace_printf_key(&trace_setup_key, "setup: git_common_dir: %s\n", quote_crnl(repo_get_common_dir(the_repository)));
 318         trace_printf_key(&trace_setup_key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
 319         trace_printf_key(&trace_setup_key, "setup: cwd: %s\n", quote_crnl(cwd));
 320         trace_printf_key(&trace_setup_key, "setup: prefix: %s\n", quote_crnl(prefix));
 321
 322         free(cwd);
 323 }
 324
 325 int trace_want(struct trace_key *key)
 326 {
 327         return !!get_trace_fd(key, NULL);
 328 }
 329
 330 #if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC)
 331
 332 static inline uint64_t highres_nanos(void)
 333 {
 334         struct timespec ts;
 335         if (clock_gettime(CLOCK_MONOTONIC, &ts))
 336                 return 0;
 337         return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
 338 }
 339
 340 #elif defined (GIT_WINDOWS_NATIVE)
 341
 342 static inline uint64_t highres_nanos(void)
 343 {
 344         static uint64_t high_ns, scaled_low_ns;
 345         static int scale;
 346         LARGE_INTEGER cnt;
 347
 348         if (!scale) {
 349                 if (!QueryPerformanceFrequency(&cnt))
 350                         return 0;
 351
 352                 /* high_ns = number of ns per cnt.HighPart */
 353                 high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;
 354
 355                 /*
 356                  * Number of ns per cnt.LowPart is 10^9 / frequency (or
 357                  * high_ns >> 32). For maximum precision, we scale this factor
 358                  * so that it just fits within 32 bit (i.e. won't overflow if
 359                  * multiplied with cnt.LowPart).
 360                  */
 361                 scaled_low_ns = high_ns;
 362                 scale = 32;
 363                 while (scaled_low_ns >= 0x100000000LL) {
 364                         scaled_low_ns >>= 1;
 365                         scale--;
 366                 }
 367         }
 368
 369         /* if QPF worked on initialization, we expect QPC to work as well */
 370         QueryPerformanceCounter(&cnt);
 371
 372         return (high_ns * cnt.HighPart) +
 373                ((scaled_low_ns * cnt.LowPart) >> scale);
 374 }
 375
 376 #else
 377 # define highres_nanos() 0
 378 #endif
 379
 380 static inline uint64_t gettimeofday_nanos(void)
 381 {
 382         struct timeval tv;
 383         gettimeofday(&tv, NULL);
 384         return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
 385 }
 386
 387 /*
 388  * Returns nanoseconds since the epoch (01/01/1970), for performance tracing
 389  * (i.e. favoring high precision over wall clock time accuracy).
 390  */
 391 uint64_t getnanotime(void)
 392 {
 393         static uint64_t offset;
 394         if (offset > 1) {
 395                 /* initialization succeeded, return offset + high res time */
 396                 return offset + highres_nanos();
 397         } else if (offset == 1) {
 398                 /* initialization failed, fall back to gettimeofday */
 399                 return gettimeofday_nanos();
 400         } else {
 401                 /* initialize offset if high resolution timer works */
 402                 uint64_t now = gettimeofday_nanos();
 403                 uint64_t highres = highres_nanos();
 404                 if (highres)
 405                         offset = now - highres;
 406                 else
 407                         offset = 1;
 408                 return now;
 409         }
 410 }
 411
 412 static struct strbuf command_line = STRBUF_INIT;
 413
 414 static void print_command_performance_atexit(void)
 415 {
 416         trace_performance_leave("git command:%s", command_line.buf);
 417 }
 418
 419 void trace_command_performance(const char **argv)
 420 {
 421         if (!trace_want(&trace_perf_key))
 422                 return;
 423
 424         if (!command_line.len)
 425                 atexit(print_command_performance_atexit);
 426
 427         strbuf_reset(&command_line);
 428         sq_quote_argv_pretty(&command_line, argv);
 429         trace_performance_enter();
 430 }