Clarify some errors in pg_receivewal when closing WAL segments

michaelpq · michaelpq · commit cddcf7842c31 · 2021-09-17T15:53:01.000+09:00
A WAL segment closed during a WAL stream for pg_receivewal would generate incorrect error messages depending on the context, as the file name used when referring to a WAL segment ignored partial files or the compression method used. In such cases, the error message generated (failure on close, seek or rename) would not match a physical file name. The same code paths are used by pg_basebackup, but it uses no partial suffix so it is not impacted. 7fbe0c8 has introduced in walmethods.c a callback to get the exact physical file name used for a given context, this commit makes use of it to improve those error messages. This could be extended to more code paths of pg_basebackup/ in the future, if necessary. Extracted from a larger patch by the same author. Author: Georgios Kokolatos Discussion: https://postgr.es/m/ZCm1J5vfyQ2E6dYvXz8si39HQ2gwxSZ3IpYaVgYa3lUwY88SLapx9EEnOf5uEwrddhx2twG7zYKjVeuP5MwZXCNPybtsGouDsAD1o2L_I5E=@pm.me
diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c
@@ -185,20 +185,27 @@ open_walfile(StreamCtl *stream, XLogRecPtr startpoint)
 static bool
 close_walfile(StreamCtl *stream, XLogRecPtr pos)
 {
+	char	   *fn;
 	off_t		currpos;
 	int			r;
 
 	if (walfile == NULL)
 		return true;
 
+	/* Note that this considers the compression used if necessary */
+	fn = stream->walmethod->get_file_name(current_walfile_name,
+										  stream->partial_suffix);
+
 	currpos = stream->walmethod->get_current_pos(walfile);
+
 	if (currpos == -1)
 	{
 		pg_log_error("could not determine seek position in file \"%s\": %s",
-					 current_walfile_name, stream->walmethod->getlasterror());
+					 fn, stream->walmethod->getlasterror());
 		stream->walmethod->close(walfile, CLOSE_UNLINK);
 		walfile = NULL;
 
+		pg_free(fn);
 		return false;
 	}
 
@@ -208,8 +215,7 @@ close_walfile(StreamCtl *stream, XLogRecPtr pos)
 			r = stream->walmethod->close(walfile, CLOSE_NORMAL);
 		else
 		{
-			pg_log_info("not renaming \"%s%s\", segment is not complete",
-						current_walfile_name, stream->partial_suffix);
+			pg_log_info("not renaming \"%s\", segment is not complete", fn);
 			r = stream->walmethod->close(walfile, CLOSE_NO_RENAME);
 		}
 	}
@@ -221,10 +227,14 @@ close_walfile(StreamCtl *stream, XLogRecPtr pos)
 	if (r != 0)
 	{
 		pg_log_error("could not close file \"%s\": %s",
-					 current_walfile_name, stream->walmethod->getlasterror());
+					 fn, stream->walmethod->getlasterror());
+
+		pg_free(fn);
 		return false;
 	}
 
+	pg_free(fn);
+
 	/*
 	 * Mark file as archived if requested by the caller - pg_basebackup needs
 	 * to do so as files can otherwise get archived again after promotion of a
