[PATCH v2 2/2] connect, protocol: log negotiated protocol version

[Josh Steadmon <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>
---
 connect.c                             |  3 +++
 protocol.c                            |  3 +++
 t/t5705-session-id-in-capabilities.sh | 12 ++++++++++++
 3 files changed, 18 insertions(+)

diff --git a/connect.c b/connect.c
index 70b13389ba..5f0e113625 100644
--- a/connect.c
+++ b/connect.c
@@ -150,6 +150,9 @@ enum protocol_version discover_version(struct packet_reader *reader)
 		break;
 	}
 
+	trace2_data_string("transfer", NULL, "negotiated-version",
+			   format_protocol_version(version));
+
 	switch (version) {
 	case protocol_v2:
 		process_capabilities_v2(reader);
diff --git a/protocol.c b/protocol.c
index 7ec7ce896e..f52dc2d7a2 100644
--- a/protocol.c
+++ b/protocol.c
@@ -87,6 +87,9 @@ enum protocol_version determine_protocol_version_server(void)
 		string_list_clear(&list, 0);
 	}
 
+	trace2_data_string("transfer", NULL, "negotiated-version",
+			   format_protocol_version(version));
+
 	return version;
 }
 
diff --git a/t/t5705-session-id-in-capabilities.sh b/t/t5705-session-id-in-capabilities.sh
index f1d189d5bc..88871c59b5 100755
--- a/t/t5705-session-id-in-capabilities.sh
+++ b/t/t5705-session-id-in-capabilities.sh
@@ -40,6 +40,7 @@ do
 		test -z "$(grep \"key\":\"server-sid\" tr2-client-events)" &&
 		test -z "$(grep \"key\":\"client-sid\" tr2-server-events)"
 	'
+
 done
 
 test_expect_success 'enable SID advertisement' '
@@ -73,6 +74,17 @@ do
 		grep \"key\":\"server-sid\" tr2-client-events &&
 		grep \"key\":\"client-sid\" tr2-server-events
 	'
+
+	test_expect_success "client & server log negotiated version (v${PROTO})" '
+		test_when_finished "rm -rf local tr2-client-events tr2-server-events" &&
+		cp -r "$LOCAL_PRISTINE" local &&
+		GIT_TRACE2_EVENT="$(pwd)/tr2-client-events" \
+		git -c protocol.version=$PROTO -C local fetch \
+			--upload-pack "GIT_TRACE2_EVENT=\"$(pwd)/tr2-server-events\" git-upload-pack" \
+			origin &&
+		test "$(grep \"key\":\"negotiated-version\",\"value\":\"$PROTO\" tr2-client-events)" &&
+		test "$(grep \"key\":\"negotiated-version\",\"value\":\"$PROTO\" tr2-server-events)"
+	'
 done
 
 test_done
-- 
2.32.0.554.ge1b32706d8-goog