log.c: message format

- Log-level name (INFO/ERROR/…) should be in the first column, so that
  filtering by log-level is maximally trivial.
- Use 2-digit year. 4-digit year is useless, logs don't survive for
  decades without context.

Before:
    2018/07/05 17:49:41 INFO  27596 on_process_exit:393: foo
After:
    INFO  180705.174941 27596 on_process_exit:393: foo

1 files changed, 7 insertions, 7 deletions

diff --git a/src/nvim/log.c b/src/nvim/log.c
index ef5b7699af..3d689db117 100644
--- a/src/nvim/log.c
+++ b/src/nvim/log.c
@@ -260,25 +260,25 @@ static bool v_do_log_to_file(FILE *log_file, int log_level,
   };
   assert(log_level >= DEBUG_LOG_LEVEL && log_level <= ERROR_LOG_LEVEL);
 
-  // format current timestamp in local time
+  // Format the timestamp.
   struct tm local_time;
   if (os_localtime(&local_time) == NULL) {
     return false;
   }
   char date_time[20];
-  if (strftime(date_time, sizeof(date_time), "%Y/%m/%d %H:%M:%S",
+  if (strftime(date_time, sizeof(date_time), "%y%m%d.%H%M%S",
                &local_time) == 0) {
     return false;
   }
 
-  // print the log message prefixed by the current timestamp and pid
+  // Print the log message.
   int64_t pid = os_get_pid();
   int rv = (line_num == -1 || func_name == NULL)
-    ? fprintf(log_file, "%s %s %" PRId64 " %s", date_time,
-              log_levels[log_level], pid,
+    ? fprintf(log_file, "%s %s %" PRId64 " %s", log_levels[log_level],
+              date_time, pid,
               (context == NULL ? "?:" : context))
-    : fprintf(log_file, "%s %s %" PRId64 " %s%s:%d: ", date_time,
-              log_levels[log_level], pid,
+    : fprintf(log_file, "%s %s %" PRId64 " %s%s:%d: ", log_levels[log_level],
+              date_time, pid,
               (context == NULL ? "" : context),
               func_name, line_num);
   if (rv < 0) {