Allow pg_basebackup to stream transaction log in tar mode

This will write the received transaction log into a file called
pg_wal.tar(.gz) next to the other tarfiles instead of writing it to
base.tar. When using fetch mode, the transaction log is still written to
base.tar like before, and when used against a pre-10 server, the file
is named pg_xlog.tar.

To do this, implement a new concept of a "walmethod", which is
responsible for writing the WAL. Two implementations exist, one that
writes to a plain directory (which is also used by pg_receivexlog) and
one that writes to a tar file with optional compression.

Reviewed by Michael Paquier

1 files changed, 9 insertions, 1 deletions

diff --git a/src/bin/pg_basebackup/pg_receivexlog.c b/src/bin/pg_basebackup/pg_receivexlog.c
index a58a251a59f..bbdf96edfd2 100644
--- a/src/bin/pg_basebackup/pg_receivexlog.c
+++ b/src/bin/pg_basebackup/pg_receivexlog.c
@@ -338,11 +338,19 @@ StreamLog(void)
 	stream.synchronous = synchronous;
 	stream.do_sync = true;
 	stream.mark_done = false;
-	stream.basedir = basedir;
+	stream.walmethod = CreateWalDirectoryMethod(basedir, stream.do_sync);
 	stream.partial_suffix = ".partial";
 
 	ReceiveXlogStream(conn, &stream);
 
+	if (!stream.walmethod->finish())
+	{
+		fprintf(stderr,
+				_("%s: could not finish writing WAL files: %s\n"),
+				progname, strerror(errno));
+		return;
+	}
+
 	PQfinish(conn);
 	conn = NULL;
 }