weston-log: Extract helper for generating a time stamp

As we might be needing it for other scopes extract the time stamp
genration into a helper.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

compositor/main.c

@@ -134,37 +134,6 @@ static struct weston_log_scope *log_scope;
 static struct weston_log_scope *protocol_scope;
 static int cached_tm_mday = -1;
 
-static char *
-weston_log_timestamp(char *buf, size_t len)
-{
-	struct timeval tv;
-	struct tm *brokendown_time;
-	char datestr[128];
-	char timestr[128];
-
-	gettimeofday(&tv, NULL);
-
-	brokendown_time = localtime(&tv.tv_sec);
-	if (brokendown_time == NULL) {
-		snprintf(buf, len, "%s", "[(NULL)localtime] ");
-		return buf;
-	}
-
-	memset(datestr, 0, sizeof(datestr));
-	if (brokendown_time->tm_mday != cached_tm_mday) {
-		strftime(datestr, sizeof(datestr), "Date: %Y-%m-%d %Z\n",
-			 brokendown_time);
-		cached_tm_mday = brokendown_time->tm_mday;
-	}
-
-	strftime(timestr, sizeof(timestr), "%H:%M:%S", brokendown_time);
-	/* if datestr is empty it prints only timestr*/
-	snprintf(buf, len, "%s[%s.%03li]", datestr,
-		 timestr, (tv.tv_usec / 1000));
-
-	return buf;
-}
-
 static void
 custom_handler(const char *fmt, va_list arg)
 {
@@ -172,7 +141,7 @@ custom_handler(const char *fmt, va_list arg)
 
 	weston_log_scope_printf(log_scope, "%s libwayland: ",
 				weston_log_timestamp(timestr,
-				sizeof(timestr)));
+				sizeof(timestr), &cached_tm_mday));
 	weston_log_scope_vprintf(log_scope, fmt, arg);
 }
 
@@ -218,7 +187,8 @@ vlog(const char *fmt, va_list ap)
 	if (weston_log_scope_is_enabled(log_scope)) {
 		int len_va;
 		char *log_timestamp = weston_log_timestamp(timestr,
-							   sizeof(timestr));
+							   sizeof(timestr),
+							   &cached_tm_mday);
 		len_va = vasprintf(&str, fmt, ap);
 		if (len_va >= 0) {
 			len = weston_log_scope_printf(log_scope, "%s %s",

include/libweston/weston-log.h

@@ -109,6 +109,8 @@ weston_log_subscription_complete(struct weston_log_subscription *sub);
 char *
 weston_log_scope_timestamp(struct weston_log_scope *scope,
 			     char *buf, size_t len);
+char *
+weston_log_timestamp(char *buf, size_t len, int *cached_tm_mday);
 
 void
 weston_log_subscriber_destroy(struct weston_log_subscriber *subscriber);

libweston/weston-log.c

@@ -913,6 +913,56 @@ weston_log_scope_timestamp(struct weston_log_scope *scope,
 	return buf;
 }
 
+/** Returns a timestamp useful for adding it to a log scope.
+ *
+ * @example
+ * char timestr[128];
+ * static int cached_dm = -1;
+ * char *time_buff = weston_log_timestamp(timestr, sizeof(timestr),  &cached_dm);
+ * weston_log_scope_printf(log_scope, "%s %s", time_buff, other_data);
+ *
+ * @param buf a user-supplied buffer
+ * @param len user-supplied length of the buffer
+ * @param cached_tm_mday a cached day of the month, as an integer. Setting this
+ * pointer different from NULL, to an integer value other than was retrieved as
+ * current day of the month, would add an additional line under the form of
+ * 'Date: Y-m-d Z\n'. Setting the pointer to NULL would not print any date, nor
+ * if the value matches the current day of month. Helps identify logs that
+ * spawn multiple days, while still having a shorter time stamp format.
+ * @ingroup log
+ */
+WL_EXPORT char *
+weston_log_timestamp(char *buf, size_t len, int *cached_tm_mday)
+{
+       struct timeval tv;
+       struct tm *brokendown_time;
+       char datestr[128];
+       char timestr[128];
+
+       gettimeofday(&tv, NULL);
+
+       brokendown_time = localtime(&tv.tv_sec);
+       if (brokendown_time == NULL) {
+               snprintf(buf, len, "%s", "[(NULL)localtime] ");
+               return buf;
+       }
+
+       memset(datestr, 0, sizeof(datestr));
+       if (cached_tm_mday && brokendown_time->tm_mday != *cached_tm_mday) {
+               strftime(datestr, sizeof(datestr), "Date: %Y-%m-%d %Z\n",
+                        brokendown_time);
+               *cached_tm_mday = brokendown_time->tm_mday;
+       }
+
+       strftime(timestr, sizeof(timestr), "%H:%M:%S", brokendown_time);
+       /* if datestr is empty it prints only timestr*/
+       snprintf(buf, len, "%s[%s.%03li]", datestr,
+                timestr, (tv.tv_usec / 1000));
+
+       return buf;
+}
+
+
 void
 weston_log_subscriber_release(struct weston_log_subscriber *subscriber)
 {