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57 lines
2.6 KiB
57 lines
2.6 KiB
commit f87ea7d2fdcfa3ccd5d605b3ce96642d28f20f6b
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Author: Willy Tarreau <w@1wt.eu>
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Date: Fri Aug 24 14:31:53 2018 +0200
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BUG/MEDIUM: unix: provide a ->drain() function
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Right now conn_sock_drain() calls the protocol's ->drain() function if
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it exists, otherwise it simply tries to disable polling for receiving
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on the connection. This doesn't work well anymore since we've implemented
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the muxes in 1.8, and it has a side effect with keep-alive backend
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connections established over unix sockets. What happens is that if
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during the idle time after a request, a connection reports some data,
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si_idle_conn_null_cb() is called, which will call conn_sock_drain().
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This one sees there's no drain() on unix sockets and will simply disable
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polling for data on the connection. But it doesn't do anything on the
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conn_stream. Thus while leaving the conn_fd_handler, the mux's polling
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is updated and recomputed based on the conn_stream's polling state,
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which is still enabled, and nothing changes, so we see the process
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use 100% CPU in this case because the FD remains active in the cache.
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There are several issues that need to be addressed here. The first and
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most important is that we cannot expect some protocols to simply stop
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reading data when asked to drain pending data. So this patch make the
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unix sockets rely on tcp_drain() since the functions are the same. This
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solution is appropriate for backporting, but a better one is desired for
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the long term. The second issue is that si_idle_conn_null_cb() shouldn't
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drain the connection but the conn_stream.
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At the moment we don't have any way to drain a conn_stream, though a flag
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on rcv_buf() will do it well. Until we support muxes on the server side
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it is not a problem so this part can be addressed later.
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This fix must be backported to 1.8.
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(cherry picked from commit fe5d2ac65fd58a8320e8dc725219c1bce5839592)
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Signed-off-by: Willy Tarreau <w@1wt.eu>
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diff --git a/src/proto_uxst.c b/src/proto_uxst.c
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index f2374be6..0b3a57b8 100644
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--- a/src/proto_uxst.c
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+++ b/src/proto_uxst.c
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@@ -42,6 +42,7 @@
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#include <proto/listener.h>
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#include <proto/log.h>
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#include <proto/protocol.h>
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+#include <proto/proto_tcp.h>
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#include <proto/task.h>
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static int uxst_bind_listener(struct listener *listener, char *errmsg, int errlen);
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@@ -71,6 +72,7 @@ static struct protocol proto_unix = {
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.disable_all = disable_all_listeners,
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.get_src = uxst_get_src,
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.get_dst = uxst_get_dst,
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+ .drain = tcp_drain,
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.pause = uxst_pause_listener,
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.add = uxst_add_listener,
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.listeners = LIST_HEAD_INIT(proto_unix.listeners),
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