trace.c
/*
* GIT - The information manager from hell
*
* Copyright (C) 2000-2002 Michael R. Elkins <me@mutt.org>
* Copyright (C) 2002-2004 Oswald Buddenhagen <ossi@users.sf.net>
* Copyright (C) 2004 Theodore Y. Ts'o <tytso@mit.edu>
* Copyright (C) 2006 Mike McCormack
* Copyright (C) 2006 Christian Couder
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include "git-compat-util.h"
#include "abspath.h"
#include "environment.h"
#include "quote.h"
#include "setup.h"
#include "trace.h"
struct trace_key trace_default_key = { "GIT_TRACE", 0, 0, 0 };
struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
struct trace_key trace_setup_key = TRACE_KEY_INIT(SETUP);
/* Get a trace file descriptor from "key" env variable. */
static int get_trace_fd(struct trace_key *key, const char *override_envvar)
{
const char *trace;
/* don't open twice */
if (key->initialized)
return key->fd;
trace = override_envvar ? override_envvar : getenv(key->key);
if (!trace || !strcmp(trace, "") ||
!strcmp(trace, "0") || !strcasecmp(trace, "false"))
key->fd = 0;
else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
key->fd = STDERR_FILENO;
else if (strlen(trace) == 1 && isdigit(*trace))
key->fd = atoi(trace);
else if (is_absolute_path(trace)) {
int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
if (fd == -1) {
warning("could not open '%s' for tracing: %s",
trace, strerror(errno));
trace_disable(key);
} else {
key->fd = fd;
key->need_close = 1;
}
} else {
warning("unknown trace value for '%s': %s\n"
" If you want to trace into a file, then please set %s\n"
" to an absolute pathname (starting with /)",
key->key, trace, key->key);
trace_disable(key);
}
key->initialized = 1;
return key->fd;
}
void trace_override_envvar(struct trace_key *key, const char *value)
{
trace_disable(key);
key->initialized = 0;
/*
* Invoke get_trace_fd() to initialize key using the given value
* instead of the value of the environment variable.
*/
get_trace_fd(key, value);
}
void trace_disable(struct trace_key *key)
{
if (key->need_close)
close(key->fd);
key->fd = 0;
key->initialized = 1;
key->need_close = 0;
}
static int prepare_trace_line(const char *file, int line,
struct trace_key *key, struct strbuf *buf)
{
static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
struct timeval tv;
struct tm tm;
time_t secs;
if (!trace_want(key))
return 0;
/* unit tests may want to disable additional trace output */
if (trace_want(&trace_bare))
return 1;
/* print current timestamp */
gettimeofday(&tv, NULL);
secs = tv.tv_sec;
localtime_r(&secs, &tm);
strbuf_addf(buf, "%02d:%02d:%02d.%06ld %s:%d", tm.tm_hour, tm.tm_min,
tm.tm_sec, (long) tv.tv_usec, file, line);
/* align trace output (column 40 catches most files names in git) */
while (buf->len < 40)
strbuf_addch(buf, ' ');
return 1;
}
static void trace_write(struct trace_key *key, const void *buf, unsigned len)
{
if (write_in_full(get_trace_fd(key, NULL), buf, len) < 0) {
warning("unable to write trace for %s: %s",
key->key, strerror(errno));
trace_disable(key);
}
}
void trace_verbatim(struct trace_key *key, const void *buf, unsigned len)
{
if (!trace_want(key))
return;
trace_write(key, buf, len);
}
static void print_trace_line(struct trace_key *key, struct strbuf *buf)
{
strbuf_complete_line(buf);
trace_write(key, buf->buf, buf->len);
}
static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
const char *format, va_list ap)
{
struct strbuf buf = STRBUF_INIT;
if (!prepare_trace_line(file, line, key, &buf))
return;
strbuf_vaddf(&buf, format, ap);
print_trace_line(key, &buf);
strbuf_release(&buf);
}
static void trace_argv_vprintf_fl(const char *file, int line,
const char **argv, const char *format,
va_list ap)
{
struct strbuf buf = STRBUF_INIT;
if (!prepare_trace_line(file, line, &trace_default_key, &buf))
return;
strbuf_vaddf(&buf, format, ap);
sq_quote_argv_pretty(&buf, argv);
print_trace_line(&trace_default_key, &buf);
strbuf_release(&buf);
}
void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
const struct strbuf *data)
{
struct strbuf buf = STRBUF_INIT;
if (!prepare_trace_line(file, line, key, &buf))
return;
strbuf_addbuf(&buf, data);
print_trace_line(key, &buf);
strbuf_release(&buf);
}
static uint64_t perf_start_times[10];
static int perf_indent;
uint64_t trace_performance_enter(void)
{
uint64_t now;
if (!trace_want(&trace_perf_key))
return 0;
now = getnanotime();
perf_start_times[perf_indent] = now;
if (perf_indent + 1 < ARRAY_SIZE(perf_start_times))
perf_indent++;
else
BUG("Too deep indentation");
return now;
}
static void trace_performance_vprintf_fl(const char *file, int line,
uint64_t nanos, const char *format,
va_list ap)
{
static const char space[] = " ";
struct strbuf buf = STRBUF_INIT;
if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
return;
strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);
if (format && *format) {
if (perf_indent >= strlen(space))
BUG("Too deep indentation");
strbuf_addf(&buf, ":%.*s ", perf_indent, space);
strbuf_vaddf(&buf, format, ap);
}
print_trace_line(&trace_perf_key, &buf);
strbuf_release(&buf);
}
void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
const char *format, ...)
{
va_list ap;
va_start(ap, format);
trace_vprintf_fl(file, line, key, format, ap);
va_end(ap);
}
void trace_argv_printf_fl(const char *file, int line, const char **argv,
const char *format, ...)
{
va_list ap;
va_start(ap, format);
trace_argv_vprintf_fl(file, line, argv, format, ap);
va_end(ap);
}
void trace_performance_fl(const char *file, int line, uint64_t nanos,
const char *format, ...)
{
va_list ap;
va_start(ap, format);
trace_performance_vprintf_fl(file, line, nanos, format, ap);
va_end(ap);
}
void trace_performance_leave_fl(const char *file, int line,
uint64_t nanos, const char *format, ...)
{
va_list ap;
uint64_t since;
if (perf_indent)
perf_indent--;
if (!format) /* Allow callers to leave without tracing anything */
return;
since = perf_start_times[perf_indent];
va_start(ap, format);
trace_performance_vprintf_fl(file, line, nanos - since, format, ap);
va_end(ap);
}
static const char *quote_crnl(const char *path)
{
static struct strbuf new_path = STRBUF_INIT;
if (!path)
return NULL;
strbuf_reset(&new_path);
while (*path) {
switch (*path) {
case '\\': strbuf_addstr(&new_path, "\\\\"); break;
case '\n': strbuf_addstr(&new_path, "\\n"); break;
case '\r': strbuf_addstr(&new_path, "\\r"); break;
default:
strbuf_addch(&new_path, *path);
}
path++;
}
return new_path.buf;
}
void trace_repo_setup(void)
{
const char *git_work_tree, *prefix = startup_info->prefix;
char *cwd;
if (!trace_want(&trace_setup_key))
return;
cwd = xgetcwd();
if (!(git_work_tree = get_git_work_tree()))
git_work_tree = "(null)";
if (!startup_info->prefix)
prefix = "(null)";
trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
trace_printf_key(&trace_setup_key, "setup: git_common_dir: %s\n", quote_crnl(get_git_common_dir()));
trace_printf_key(&trace_setup_key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
trace_printf_key(&trace_setup_key, "setup: cwd: %s\n", quote_crnl(cwd));
trace_printf_key(&trace_setup_key, "setup: prefix: %s\n", quote_crnl(prefix));
free(cwd);
}
int trace_want(struct trace_key *key)
{
return !!get_trace_fd(key, NULL);
}
#if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC)
static inline uint64_t highres_nanos(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
return 0;
return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
}
#elif defined (GIT_WINDOWS_NATIVE)
static inline uint64_t highres_nanos(void)
{
static uint64_t high_ns, scaled_low_ns;
static int scale;
LARGE_INTEGER cnt;
if (!scale) {
if (!QueryPerformanceFrequency(&cnt))
return 0;
/* high_ns = number of ns per cnt.HighPart */
high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;
/*
* Number of ns per cnt.LowPart is 10^9 / frequency (or
* high_ns >> 32). For maximum precision, we scale this factor
* so that it just fits within 32 bit (i.e. won't overflow if
* multiplied with cnt.LowPart).
*/
scaled_low_ns = high_ns;
scale = 32;
while (scaled_low_ns >= 0x100000000LL) {
scaled_low_ns >>= 1;
scale--;
}
}
/* if QPF worked on initialization, we expect QPC to work as well */
QueryPerformanceCounter(&cnt);
return (high_ns * cnt.HighPart) +
((scaled_low_ns * cnt.LowPart) >> scale);
}
#else
# define highres_nanos() 0
#endif
static inline uint64_t gettimeofday_nanos(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
}
/*
* Returns nanoseconds since the epoch (01/01/1970), for performance tracing
* (i.e. favoring high precision over wall clock time accuracy).
*/
uint64_t getnanotime(void)
{
static uint64_t offset;
if (offset > 1) {
/* initialization succeeded, return offset + high res time */
return offset + highres_nanos();
} else if (offset == 1) {
/* initialization failed, fall back to gettimeofday */
return gettimeofday_nanos();
} else {
/* initialize offset if high resolution timer works */
uint64_t now = gettimeofday_nanos();
uint64_t highres = highres_nanos();
if (highres)
offset = now - highres;
else
offset = 1;
return now;
}
}
static struct strbuf command_line = STRBUF_INIT;
static void print_command_performance_atexit(void)
{
trace_performance_leave("git command:%s", command_line.buf);
}
void trace_command_performance(const char **argv)
{
if (!trace_want(&trace_perf_key))
return;
if (!command_line.len)
atexit(print_command_performance_atexit);
strbuf_reset(&command_line);
sq_quote_argv_pretty(&command_line, argv);
trace_performance_enter();
}