log: Added a switch to the log date and time format.

It is possible to switch back to full date and time on each log line with "--log-dateformat 1". The short time-only format is default with the value of 0.

Log with short time-only format looks like:
 [23:59:59] Accepted 389c47d1 Diff 1.16K/512 GPU 0 pool 0
 [00:00:16] Log date is now 2013-12-22
 [00:00:16] Stratum from pool 0 detected new block
 [00:00:33] Accepted 7a4950a4 Diff 536/512 GPU 0 pool 0

cgminer.c

@@ -1078,6 +1078,9 @@ static struct opt_table opt_config_table[] = {
 	OPT_WITH_ARG("--log|-l",
 		     set_int_0_to_9999, opt_show_intval, &opt_log_interval,
 		     "Interval in seconds between log output"),
+	OPT_WITH_ARG("--log-dateformat",
+		     set_int_0_to_10, opt_show_intval, &opt_log_dateformat,
+		     "Set log dateformat (0 or 1) - 0 is time only, 1 is full date and time."),
 	OPT_WITHOUT_ARG("--lowmem",
 			opt_set_bool, &opt_lowmem,
 			"Minimise caching of shares for low memory applications"),

logging.c

@@ -17,6 +17,8 @@
 
 bool opt_debug = false;
 bool opt_log_output = false;
+int last_date_output_day = 0;
+int opt_log_dateformat = 0;
 
 /* per default priorities higher than LOG_NOTICE are logged */
 int opt_log_level = LOG_NOTICE;
@@ -69,13 +71,35 @@ void _applog(int prio, const char *str, bool force)
 		const time_t tmp_time = tv.tv_sec;
 		tm = localtime(&tmp_time);
 
-		snprintf(datetime, sizeof(datetime), " [%d-%02d-%02d %02d:%02d:%02d] ",
-			tm->tm_year + 1900,
-			tm->tm_mon + 1,
-			tm->tm_mday,
-			tm->tm_hour,
-			tm->tm_min,
-			tm->tm_sec);
+		if ((opt_log_dateformat == 0) && (last_date_output_day != tm->tm_mday))
+		{
+			last_date_output_day = tm->tm_mday;
+			char date_output_str[64];
+			snprintf(date_output_str, sizeof(date_output_str), "Log date is now %d-%02d-%02d",
+				tm->tm_year + 1900,
+				tm->tm_mon + 1,
+				tm->tm_mday);
+			_applog(prio, date_output_str, force);
+			
+		}
+
+		if (opt_log_dateformat == 1)
+		{
+			snprintf(datetime, sizeof(datetime), " [%d-%02d-%02d %02d:%02d:%02d] ",
+				tm->tm_year + 1900,
+				tm->tm_mon + 1,
+				tm->tm_mday,
+				tm->tm_hour,
+				tm->tm_min,
+				tm->tm_sec);
+		}
+		else
+		{
+			snprintf(datetime, sizeof(datetime), " [%02d:%02d:%02d] ",
+				tm->tm_hour,
+				tm->tm_min,
+				tm->tm_sec);
+		}
 
 		/* Only output to stderr if it's not going to the screen as well */
 		if (!isatty(fileno((FILE *)stderr))) {

logging.h

@@ -26,6 +26,8 @@ extern bool want_per_device_stats;
 /* global log_level, messages with lower or equal prio are logged */
 extern int opt_log_level;
 
+extern int opt_log_dateformat;
+
 #define LOGBUFSIZ 256
 
 extern void _applog(int prio, const char *str, bool force);