From c4f49a53426265594206b1c88ccab32bbffcef80 Mon Sep 17 00:00:00 2001
From: Amitay Isaacs <amitay@gmail.com>
Date: Fri, 6 Sep 2013 18:11:40 +1000
Subject: [PATCH] traverse: Check if local traverse failed or succeeded

By passing the result of tdb_traverse_read() allows ctdbd to determine
if the local traverse succeeded or not.  In case of a problem with local
traverse, ctdbd can log an error.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>

(This used to be ctdb commit abd51a9f41ebb178c4ea4491bdedf9a9433e7232)
---
 ctdb/server/ctdb_traverse.c | 42 ++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/ctdb/server/ctdb_traverse.c b/ctdb/server/ctdb_traverse.c
index e37ba9c2dae..83fd5dc1dfc 100644
--- a/ctdb/server/ctdb_traverse.c
+++ b/ctdb/server/ctdb_traverse.c
@@ -44,6 +44,8 @@ struct ctdb_traverse_local_handle {
 	ctdb_traverse_fn_t callback;
 	bool withemptyrecords;
 	struct tevent_fd *fde;
+	int records_failed;
+	int records_sent;
 };
 
 /*
@@ -56,12 +58,25 @@ static void ctdb_traverse_child_handler(struct tevent_context *ev, struct tevent
 							struct ctdb_traverse_local_handle);
 	ctdb_traverse_fn_t callback = h->callback;
 	void *p = h->private_data;
-	char res;
+	int res;
+	ssize_t n;
+
+	/* Read the number of records sent by traverse child */
+	n = read(h->fd[0], &res, sizeof(res));
+	if (n < 0 || n != sizeof(res)) {
+		/* Traverse child failed */
+		DEBUG(DEBUG_ERR, ("Local traverse failed db:%s reqid:%d\n",
+				  h->ctdb_db->db_name, h->reqid));
+	} else if (res < 0) {
+		/* Traverse failed */
+		res = -res;
+		DEBUG(DEBUG_ERR, ("Local traverse failed db:%s reqid:%d records:%d\n",
+				  h->ctdb_db->db_name, h->reqid, res));
+	} else {
+		DEBUG(DEBUG_INFO, ("Local traverse end db:%s reqid:%d records:%d\n",
+				   h->ctdb_db->db_name, h->reqid, res));
+	}
 
-	/* FIXME: There is no way to distinguish between failed traverse and
-	 * successful traverse.  The only way to signal the end is by sending
-	 * tdb_null for key and data. */
-	read(h->fd[0], &res, 1);
 	callback(p, tdb_null, tdb_null);
 }
 
@@ -106,6 +121,7 @@ static int ctdb_traverse_local_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DAT
 	d = ctdb_marshall_record(h, h->reqid, key, NULL, data);
 	if (d == NULL) {
 		/* error handling is tricky in this child code .... */
+		h->records_failed++;
 		return -1;
 	}
 
@@ -115,9 +131,11 @@ static int ctdb_traverse_local_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DAT
 	res = ctdb_control(h->ctdb_db->ctdb, h->srcnode, 0, CTDB_CONTROL_TRAVERSE_DATA,
 			   CTDB_CTRL_FLAG_NOREPLY, outdata, NULL, NULL, &status, NULL, NULL);
 	if (res != 0 || status != 0) {
+		h->records_failed++;
 		return -1;
 	}
 
+	h->records_sent++;
 	return 0;
 }
 
@@ -177,7 +195,7 @@ static struct ctdb_traverse_local_handle *ctdb_traverse_local(struct ctdb_db_con
 
 	if (h->child == 0) {
 		/* start the traverse in the child */
-		char res = 0;
+		int res;
 		pid_t parent = getpid();
 
 		close(h->fd[0]);
@@ -187,13 +205,17 @@ static struct ctdb_traverse_local_handle *ctdb_traverse_local(struct ctdb_db_con
 						 "traverse_local-%s:",
 						 ctdb_db->db_name) != 0) {
 			DEBUG(DEBUG_CRIT, ("Failed to switch traverse child into client mode\n"));
-			res = -1;
+			_exit(0);
 		}
 
-		if (tdb_traverse_read(ctdb_db->ltdb->tdb, ctdb_traverse_local_fn, h) != 0) {
-			res = -1;
+		res = tdb_traverse_read(ctdb_db->ltdb->tdb, ctdb_traverse_local_fn, h);
+		if (res == -1 || h->records_failed > 0) {
+			/* traverse failed */
+			res = -(h->records_sent);
+		} else {
+			res = h->records_sent;
 		}
-		write(h->fd[1], &res, 1);
+		write(h->fd[1], &res, sizeof(res));
 
 		while (ctdb_kill(ctdb_db->ctdb, parent, 0) == 0 || errno != ESRCH) {
 			sleep(5);