1 files changed, 435 insertions, 0 deletions
diff --git a/trace.c b/trace.c
new file mode 100644
index 0000000000..7393926ebc
--- /dev/null
+++ b/trace.c
@@ -0,0 +1,435 @@
+/*
+ * 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, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "cache.h"
+#include "quote.h"
+
+/* Get a trace file descriptor from "key" env variable. */
+static int get_trace_fd(struct trace_key *key)
+{
+	static struct trace_key trace_default = { "GIT_TRACE" };
+	const char *trace;
+
+	/* use default "GIT_TRACE" if NULL */
+	if (!key)
+		key = &trace_default;
+
+	/* don't open twice */
+	if (key->initialized)
+		return key->fd;
+
+	trace = 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) {
+			fprintf(stderr,
+				"Could not open '%s' for tracing: %s\n"
+				"Defaulting to tracing on stderr...\n",
+				trace, strerror(errno));
+			key->fd = STDERR_FILENO;
+		} else {
+			key->fd = fd;
+			key->need_close = 1;
+		}
+	} else {
+		fprintf(stderr, "What does '%s' for %s mean?\n"
+			"If you want to trace into a file, then please set "
+			"%s to an absolute pathname (starting with /).\n"
+			"Defaulting to tracing on stderr...\n",
+			trace, key->key, key->key);
+		key->fd = STDERR_FILENO;
+	}
+
+	key->initialized = 1;
+	return key->fd;
+}
+
+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 const char err_msg[] = "Could not trace into fd given by "
+	"GIT_TRACE environment variable";
+
+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;
+
+	set_try_to_free_routine(NULL);	/* is never reset */
+
+	/* 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 ", tm.tm_hour, tm.tm_min,
+		    tm.tm_sec, (long) tv.tv_usec);
+
+#ifdef HAVE_VARIADIC_MACROS
+	/* print file:line */
+	strbuf_addf(buf, "%s:%d ", file, line);
+	/* align trace output (column 40 catches most files names in git) */
+	while (buf->len < 40)
+		strbuf_addch(buf, ' ');
+#endif
+
+	return 1;
+}
+
+void trace_verbatim(struct trace_key *key, const void *buf, unsigned len)
+{
+	if (!trace_want(key))
+		return;
+	write_or_whine_pipe(get_trace_fd(key), buf, len, err_msg);
+}
+
+static void print_trace_line(struct trace_key *key, struct strbuf *buf)
+{
+	strbuf_complete_line(buf);
+
+	write_or_whine_pipe(get_trace_fd(key), buf->buf, buf->len, err_msg);
+	strbuf_release(buf);
+}
+
+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);
+}
+
+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, NULL, &buf))
+		return;
+
+	strbuf_vaddf(&buf, format, ap);
+
+	sq_quote_argv(&buf, argv, 0);
+	print_trace_line(NULL, &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);
+}
+
+static struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
+
+static void trace_performance_vprintf_fl(const char *file, int line,
+					 uint64_t nanos, const char *format,
+					 va_list ap)
+{
+	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) {
+		strbuf_addstr(&buf, ": ");
+		strbuf_vaddf(&buf, format, ap);
+	}
+
+	print_trace_line(&trace_perf_key, &buf);
+}
+
+#ifndef HAVE_VARIADIC_MACROS
+
+void trace_printf(const char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	trace_vprintf_fl(NULL, 0, NULL, format, ap);
+	va_end(ap);
+}
+
+void trace_printf_key(struct trace_key *key, const char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	trace_vprintf_fl(NULL, 0, key, format, ap);
+	va_end(ap);
+}
+
+void trace_argv_printf(const char **argv, const char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	trace_argv_vprintf_fl(NULL, 0, argv, format, ap);
+	va_end(ap);
+}
+
+void trace_strbuf(struct trace_key *key, const struct strbuf *data)
+{
+	trace_strbuf_fl(NULL, 0, key, data);
+}
+
+void trace_performance(uint64_t nanos, const char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	trace_performance_vprintf_fl(NULL, 0, nanos, format, ap);
+	va_end(ap);
+}
+
+void trace_performance_since(uint64_t start, const char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	trace_performance_vprintf_fl(NULL, 0, getnanotime() - start,
+				     format, ap);
+	va_end(ap);
+}
+
+#else
+
+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);
+}
+
+#endif /* HAVE_VARIADIC_MACROS */
+
+
+static const char *quote_crnl(const char *path)
+{
+	static char new_path[PATH_MAX];
+	const char *p2 = path;
+	char *p1 = new_path;
+
+	if (!path)
+		return NULL;
+
+	while (*p2) {
+		switch (*p2) {
+		case '\\': *p1++ = '\\'; *p1++ = '\\'; break;
+		case '\n': *p1++ = '\\'; *p1++ = 'n'; break;
+		case '\r': *p1++ = '\\'; *p1++ = 'r'; break;
+		default:
+			*p1++ = *p2;
+		}
+		p2++;
+	}
+	*p1 = '\0';
+	return new_path;
+}
+
+/* FIXME: move prefix to startup_info struct and get rid of this arg */
+void trace_repo_setup(const char *prefix)
+{
+	static struct trace_key key = TRACE_KEY_INIT(SETUP);
+	const char *git_work_tree;
+	char *cwd;
+
+	if (!trace_want(&key))
+		return;
+
+	cwd = xgetcwd();
+
+	if (!(git_work_tree = get_git_work_tree()))
+		git_work_tree = "(null)";
+
+	if (!prefix)
+		prefix = "(null)";
+
+	trace_printf_key(&key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
+	trace_printf_key(&key, "setup: git_common_dir: %s\n", quote_crnl(get_git_common_dir()));
+	trace_printf_key(&key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
+	trace_printf_key(&key, "setup: cwd: %s\n", quote_crnl(cwd));
+	trace_printf_key(&key, "setup: prefix: %s\n", quote_crnl(prefix));
+
+	free(cwd);
+}
+
+int trace_want(struct trace_key *key)
+{
+	return !!get_trace_fd(key);
+}
+
+#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 uint64_t command_start_time;
+static struct strbuf command_line = STRBUF_INIT;
+
+static void print_command_performance_atexit(void)
+{
+	trace_performance_since(command_start_time, "git command:%s",
+				command_line.buf);
+}
+
+void trace_command_performance(const char **argv)
+{
+	if (!trace_want(&trace_perf_key))
+		return;
+
+	if (!command_start_time)
+		atexit(print_command_performance_atexit);
+
+	strbuf_reset(&command_line);
+	sq_quote_argv(&command_line, argv, 0);
+	command_start_time = getnanotime();
+}