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