dbwrap_ctdb: only fetch a read-only copy if we had a record already.

Because revoking read-only copies of records is expensive, we only
want ctdbd to do it for high-turnover records.  A basic heuristic is
that if we don't find a local copy of the record, don't ask for a
read-only copy.

The fetch itself will cause ctdbd to migrate the record, so eventually
we will have a local copy.  Next time it gets migrated away, we'll
call ctdbd_fetch() with local_copy = true.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 7 insertions, 2 deletions

diff --git a/source3/lib/dbwrap/dbwrap_ctdb.c b/source3/lib/dbwrap/dbwrap_ctdb.c
index 0f4efa359c..a05f9554b7 100644
--- a/source3/lib/dbwrap/dbwrap_ctdb.c
+++ b/source3/lib/dbwrap/dbwrap_ctdb.c
@@ -1203,9 +1203,14 @@ static NTSTATUS db_ctdb_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
 
 	SAFE_FREE(ctdb_data.dptr);
 
-	/* we weren't able to get it locally - ask ctdb to fetch it for us */
+	/*
+	 * We weren't able to get it locally - ask ctdb to fetch it for us.
+	 * If we already had *something*, it's probably worth making a local
+	 * read-only copy.
+	 */
 	status = ctdbd_fetch(messaging_ctdbd_connection(), ctx->db_id, key,
-			     mem_ctx, data);
+			     mem_ctx, data,
+			     ctdb_data.dsize >= sizeof(struct ctdb_ltdb_header));
 	if (!NT_STATUS_IS_OK(status)) {
 		DEBUG(5, ("ctdbd_fetch failed: %s\n", nt_errstr(status)));
 	}