BUG/MEDIUM: stream-int: Notify stream that the mux wants more room to xfer data

When the mux failed to transfer data to the upper layer because of a lack of
room, it is important to wake the stream up to let it handle this
event. Otherwise, if the stream is waiting for more data, both the stream
and the mux reamin blocked waiting for each other.

When this happens, the mux set the CS_FL_WANT_ROOM flag on the
conn-stream. Thus, in si_cs_recv() we are able to detect this event. Today,
the stream-interface is blocked. But, it is not enough to wake the stream
up. To fix the bug, CF_READ_PARTIAL flag is extended to also handle cases
where a read exception occurred. This flag should idealy be renamed. But for
now, it is good enough. By setting this flag, we are sure the stream will be
woken up.

This patch is part of a series related to the issue #1362. It should be
backported as far as 2.0, probably with some adaptations. So be careful
during backports.

diff --git a/include/haproxy/channel-t.h b/include/haproxy/channel-t.h
index 8feb62dd25bf7132991c651cc8d11f08f4bb9287..01a0a2488bb7d45a59376c44465131bad59cf5c6 100644 (file)
--- a/include/haproxy/channel-t.h
+++ b/include/haproxy/channel-t.h
@@ -52,7 +52,7 @@
  */
 
 #define CF_READ_NULL      0x00000001  /* last read detected on producer side */
-#define CF_READ_PARTIAL   0x00000002  /* some data were read from producer */
+#define CF_READ_PARTIAL   0x00000002  /* some data were read from producer or a read exception occurred */
 #define CF_READ_TIMEOUT   0x00000004  /* timeout while waiting for producer */
 #define CF_READ_ERROR     0x00000008  /* unrecoverable error on producer side */
 #define CF_READ_ACTIVITY  (CF_READ_NULL|CF_READ_PARTIAL|CF_READ_ERROR)

diff --git a/src/stream_interface.c b/src/stream_interface.c
index 68b89525e3f8706cd2660e8cefb8fb90f8a28d1b..e5da8ea56534ad091d8caee351b53820350e3b8c 100644 (file)
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -1351,8 +1351,13 @@ int si_cs_recv(struct conn_stream *cs)
                flags |= ((!conn_is_back(conn) && (si_strm(si)->be->options & PR_O_ABRT_CLOSE)) ? CO_RFL_KEEP_RECV : 0);
                ret = cs->conn->mux->rcv_buf(cs, &ic->buf, max, flags | (co_data(ic) ? CO_RFL_BUF_WET : 0));
 
-               if (cs->flags & CS_FL_WANT_ROOM)
+               if (cs->flags & CS_FL_WANT_ROOM) {
                        si_rx_room_blk(si);
+                       /* Add READ_PARTIAL because some data are pending but
+                        * cannot be xferred to the channel
+                        */
+                       ic->flags |= CF_READ_PARTIAL;
+               }
 
                if (ret <= 0) {
                        /* if we refrained from reading because we asked for a