[generic_log] support nanosecond-precision timestamps

Author: Yukigaru

src/log_format_impls.cc

@@ -148,7 +148,7 @@ class generic_log_format : public log_format {
         static const pcre_format log_fmt[] = {
             pcre_format(R"(^(?:\*\*\*\s+)?(?<timestamp>@[0-9a-zA-Z]{16,24}))"),
             pcre_format(
-                R"(^(?:\*\*\*\s+)?(?<timestamp>(?:\s|\d{4}[\-\/]\d{2}[\-\/]\d{2}|T|\d{1,2}:\d{2}(?::\d{2}(?:[\.,]\d{1,6})?)?|Z|[+\-]\d{2}:?\d{2}|(?!DBG|DEBUG|ERR|INFO|WARN|NONE)[A-Z]{3,4})+)[:|\s]?(trc|trace|dbg|debug|info|warn(?:ing)?|err(?:or)?)[:|\s]\s*)"),
+                R"(^(?:\*\*\*\s+)?(?<timestamp>(?:\s|\d{4}[\-\/]\d{2}[\-\/]\d{2}|T|\d{1,2}:\d{2}(?::\d{2}(?:[\.,]\d{1,9})?)?|Z|[+\-]\d{2}:?\d{2}|(?!DBG|DEBUG|ERR|INFO|WARN|NONE)[A-Z]{3,4})+)[:|\s]?(trc|trace|dbg|debug|info|warn(?:ing)?|err(?:or)?)[:|\s]\s*)"),
             pcre_format(
                 R"(^(?:\*\*\*\s+)?(?<timestamp>[\w:+ \.,+/-]+) \[(trace|debug|info|warn(?:ing)?|error|critical)\]\s+)"),
             pcre_format(