[Sheepdog] [PATCH] sheep: set send/recv timeout

[MORITA Kazutaka]

send()/recv() could sleep long time if network failure happens during
network I/Os, and it prevents from incrementing epoch number because
we assumes that there is no outstanding I/O requests while updating
node membership info.  This patch fixes the problem.

It is not a problem to set a small value for timeout because I/Os are
retried automatically even if send/recv timeout has occurred.

Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
---
Hi Yibin,

I think this patch is much simpler than using timeout in poll().
How do you think?

I also tried tcp keepalive, but it doesn't work on my environment for
some reason.

Thanks,

Kazutaka


 include/net.h |    3 +++
 lib/net.c     |   27 +++++++++++++++++++++++++--
 sheep/sdnet.c |    7 +++++++
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/include/net.h b/include/net.h
index 9e51fea..2d087e2 100644
--- a/include/net.h
+++ b/include/net.h
@@ -3,6 +3,8 @@
 
 #include <sys/socket.h>
 
+#define DEFAULT_SOCKET_TIMEOUT 5 /* seconds */
+
 enum conn_state {
 	C_IO_HEADER = 0,
 	C_IO_DATA_INIT,
@@ -45,5 +47,6 @@ int create_listen_ports(int port, int (*callback)(int fd, void *), void *data);
 char *addr_to_str(char *str, int size, uint8_t *addr, uint16_t port);
 int set_nonblocking(int fd);
 int set_nodelay(int fd);
+int set_timeout(int fd);
 
 #endif
diff --git a/lib/net.c b/lib/net.c
index d4a5d9b..3caba0f 100644
--- a/lib/net.c
+++ b/lib/net.c
@@ -242,7 +242,7 @@ int do_read(int sockfd, void *buf, int len)
 reread:
 	ret = read(sockfd, buf, len);
 	if (ret < 0 || !ret) {
-		if (errno == EINTR || errno == EAGAIN)
+		if (errno == EINTR)
 			goto reread;
 		fprintf(stderr, "failed to read from socket: %m\n");
 		return 1;
@@ -275,7 +275,7 @@ static int do_write(int sockfd, struct msghdr *msg, int len)
 rewrite:
 	ret = sendmsg(sockfd, msg, 0);
 	if (ret < 0) {
-		if (errno == EINTR || errno == EAGAIN)
+		if (errno == EINTR)
 			goto rewrite;
 		fprintf(stderr, "failed to write to socket: %m\n");
 		return 1;
@@ -397,3 +397,26 @@ int set_nodelay(int fd)
 	ret = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
 	return ret;
 }
+
+int set_timeout(int fd)
+{
+	int ret;
+	const struct timeval tv = {
+		.tv_sec = DEFAULT_SOCKET_TIMEOUT,
+		.tv_usec = 0,
+	};
+
+	ret = setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
+	if (ret) {
+		eprintf("failed to set send timeout\n");
+		return ret;
+	}
+
+	ret = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+	if (ret) {
+		eprintf("failed to set recv timeout\n");
+		return ret;
+	}
+
+	return 0;
+}
diff --git a/sheep/sdnet.c b/sheep/sdnet.c
index 8455653..510fd4e 100644
--- a/sheep/sdnet.c
+++ b/sheep/sdnet.c
@@ -841,6 +841,13 @@ int get_sheep_fd(uint8_t *addr, uint16_t port, int node_idx,
 	if (fd < 0)
 		return -1;
 
+	ret = set_timeout(fd);
+	if (ret) {
+		eprintf("%m\n");
+		close(fd);
+		return -1;
+	}
+
 	ret = set_nodelay(fd);
 	if (ret) {
 		eprintf("%m\n");
-- 
1.7.2.5