git/trace.c
Ævar Arnfjörð Bjarmason 56a29d2c97 C99: remove hardcoded-out !HAVE_VARIADIC_MACROS code
Remove the "else" branches of the HAVE_VARIADIC_MACROS macro, which
have been unconditionally omitted since 765dc16888 (git-compat-util:
always enable variadic macros, 2021-01-28).

Since were always omitted, anyone trying to use a compiler without
variadic macro support to compile a git since version
git v2.31.0 or later would have had a compilation error. 10 months
across a few releases since then should have been enough time for
anyone who cared to run into that and report the issue.

In addition to that, for anyone unsetting HAVE_VARIADIC_MACROS we've
been emitting extremely verbose warnings since at least
ee4512ed48 (trace2: create new combined trace facility,
2019-02-22). That's because there is no such thing as a
"region_enter_printf" or "region_leave_printf" format, so at least
under GCC and Clang everything that includes trace.h (almost every
file) emits a couple of warnings about that.

There's a large benefit to being able to have a hard dependency rely
on variadic macros, the code surrounding usage.c is hard to maintain
if we need to write two implementations of everything, and by relying
on "__FILE__" and "__LINE__" along with "__VA_ARGS__" we can in the
future make error(), die() etc. log where they were called from. We've
also recently merged d67fc4bf0b (Merge branch 'bc/require-c99',
2021-12-10) which further cements our hard dependency on C99.

So let's delete the fallback code, and update our CodingGuidelines to
note that we depend on this. The added bullet-point starts with
lower-case for consistency with other bullet-points in that section.

The diff in "trace.h" is relatively hard to read, since we need to
retain the existing API docs, which were comments on the code used if
HAVE_VARIADIC_MACROS was not defined.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-21 19:14:19 -08:00

426 lines
10 KiB
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 <http://www.gnu.org/licenses/>.
*/
#include "cache.h"
#include "quote.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;
}
/* FIXME: move prefix to startup_info struct and get rid of this arg */
void trace_repo_setup(const char *prefix)
{
const char *git_work_tree;
char *cwd;
if (!trace_want(&trace_setup_key))
return;
cwd = xgetcwd();
if (!(git_work_tree = get_git_work_tree()))
git_work_tree = "(null)";
if (!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();
}