[PATCH] connect, protocol: log negotiated protocol version

From: Josh Steadmon <steadmon@google.com>
Date: Aug 3, 2021, 20:13 UTC
Message-ID: <f79ab95af6da3da710da2112cfcae4a042b7f7fb.1628020616.git.steadmon@google.com>

It is useful for performance monitoring and debugging purposes to know the wire protocol used for remote operations. This may differ from the version set in local configuration due to differences in version and/or configuration between the server and the client. Therefore, log the negotiated wire protocol version via trace2, for both clients and servers.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---

Do people have a preference for logging this as an integer (and therefore having "unknown protocol version" show up as "-1", or should I add a protocol_version_to_string function so that we can format it properly? For now I've erred on the side of having a smaller diff.

 connect.c  | 1 +
 protocol.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/connect.c b/connect.c
index 70b13389ba..6e23e3ff2d 100644
--- a/connect.c
+++ b/connect.c
@@ -164,6 +164,7 @@ enum protocol_version discover_version(struct packet_reader *reader)
 		BUG("unknown protocol version");
 	}
 
+	trace2_data_intmax("transfer", NULL, "negotiated-version", version);
 	return version;
 }
 
diff --git a/protocol.c b/protocol.c
index 052d7edbb9..3791d8499e 100644
--- a/protocol.c
+++ b/protocol.c
@@ -89,5 +89,6 @@ enum protocol_version determine_protocol_version_client(const char *server_respo
 			die("protocol error: server explicitly said version 0");
 	}
 
+	trace2_data_intmax("transfer", NULL, "negotiated-version", version);
 	return version;
 }

-- 
2.32.0.554.ge1b32706d8-goog