[sheepdog] [PATCH v3 3/3] gateway: fix poll() hang

[Liu Yuan]

From: Liu Yuan <tailai.ly at taobao.com>

poll() might wait for unbounded period of time,  when
    a) data in send buffer is not acked
    b) the remote node is crashed

So if we detect that the send buffer is not empty, we switch to timeout poll.

Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
---
 sheep/gateway.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/sheep/gateway.c b/sheep/gateway.c
index 41d712b..3089d7c 100644
--- a/sheep/gateway.c
+++ b/sheep/gateway.c
@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <poll.h>
+#include <sys/ioctl.h>
 
 #include "sheep_priv.h"
 
@@ -150,18 +151,32 @@ static inline void pfd_info_init(struct write_info *wi, struct pfd_info *pi)
  *
  * Return error code if any one request fails.
  */
-static int wait_forward_request(struct write_info *wi, struct sd_rsp *rsp)
+static int wait_forward_request(struct write_info *wi, struct request *req)
 {
 	int nr_sent, err_ret = SD_RES_SUCCESS, ret, pollret, i;
-	struct pfd_info pi;;
+	struct pfd_info pi;
+	struct sd_rsp *rsp = &req->rp;
 again:
 	pfd_info_init(wi, &pi);
-	pollret = poll(pi.pfds, pi.nr, -1);
+	pollret = poll(pi.pfds, pi.nr, 5000);
 	if (pollret < 0) {
 		if (errno == EINTR)
 			goto again;
 
 		panic("%m\n");
+	} else if (pollret == 0) {
+		eprintf("poll timeout %d\n", wi->nr_sent);
+
+		if (req->rq.epoch == sys_epoch())
+			goto again;
+
+		nr_sent = wi->nr_sent;
+		/* XXX Blinedly close all the connections */
+		for (i = 0; i < nr_sent; i++)
+			finish_one_write_err(wi, i);
+
+		err_ret = SD_RES_NETWORK_ERROR;
+		goto finish_write;
 	}
 
 	nr_sent = wi->nr_sent;
@@ -229,7 +244,6 @@ static int gateway_forward_request(struct request *req)
 {
 	int i, err_ret = SD_RES_SUCCESS, ret, local = -1;
 	unsigned wlen;
-	struct sd_rsp *rsp = (struct sd_rsp *)&req->rp;
 	struct sd_vnode *v;
 	struct sd_vnode *obj_vnodes[SD_MAX_COPIES];
 	uint64_t oid = req->rq.obj.oid;
@@ -288,7 +302,7 @@ static int gateway_forward_request(struct request *req)
 
 	dprintf("nr_sent %d, err %x\n", wi.nr_sent, err_ret);
 	if (wi.nr_sent > 0) {
-		ret = wait_forward_request(&wi, rsp);
+		ret = wait_forward_request(&wi, req);
 		if (ret != SD_RES_SUCCESS)
 			err_ret = ret;
 	}
-- 
1.7.10.2