From d4576a56d9b75252583f04faf6f0180b6b242db2 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Fri, 15 Sep 2017 12:56:15 +1000
Subject: [PATCH] Add some expvars to track uTP/TCP and PHE fallbacks for
 outgoing connections

---
 client.go | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/client.go b/client.go
index b87ce4ea..dc3b41f9 100644
--- a/client.go
+++ b/client.go
@@ -7,6 +7,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
+	"expvar"
 	"fmt"
 	"io"
 	"log"
@@ -534,6 +535,11 @@ func (cl *Client) dialUTP(ctx context.Context, addr string) (c net.Conn, err err
 	return
 }
 
+var (
+	dialledFirstUtp    = expvar.NewInt("dialledFirstUtp")
+	dialledFirstNotUtp = expvar.NewInt("dialledFirstNotUtp")
+)
+
 // Returns a connection over UTP or TCP, whichever is first to connect.
 func (cl *Client) dialFirst(ctx context.Context, addr string) (conn net.Conn, utp bool) {
 	ctx, cancel := context.WithCancel(ctx)
@@ -573,6 +579,13 @@ func (cl *Client) dialFirst(ctx context.Context, addr string) (conn net.Conn, ut
 	}
 	conn = res.Conn
 	utp = res.UTP
+	if conn != nil {
+		if utp {
+			dialledFirstUtp.Add(1)
+		} else {
+			dialledFirstNotUtp.Add(1)
+		}
+	}
 	return
 }
 
@@ -607,6 +620,11 @@ func (cl *Client) handshakesConnection(ctx context.Context, nc net.Conn, t *Torr
 	return
 }
 
+var (
+	initiatedConnWithPreferredHeaderEncryption = expvar.NewInt("initiatedConnWithPreferredHeaderEncryption")
+	initiatedConnWithFallbackHeaderEncryption  = expvar.NewInt("initiatedConnWithFallbackHeaderEncryption")
+)
+
 // Returns nil connection and nil error if no connection could be established
 // for valid reasons.
 func (cl *Client) establishOutgoingConn(t *Torrent, addr string) (c *connection, err error) {
@@ -622,6 +640,7 @@ func (cl *Client) establishOutgoingConn(t *Torrent, addr string) (c *connection,
 		nc.Close()
 		return
 	} else if c != nil {
+		initiatedConnWithPreferredHeaderEncryption.Add(1)
 		return
 	}
 	nc.Close()
@@ -648,6 +667,9 @@ func (cl *Client) establishOutgoingConn(t *Torrent, addr string) (c *connection,
 	if err != nil || c == nil {
 		nc.Close()
 	}
+	if err == nil && c != nil {
+		initiatedConnWithFallbackHeaderEncryption.Add(1)
+	}
 	return
 }