frontend: isolate prometheus logic to one file

frontend/http/frontend.go

@@ -10,52 +10,12 @@ import (
 	"time"
 
 	"github.com/julienschmidt/httprouter"
-	"github.com/prometheus/client_golang/prometheus"
 
 	"github.com/chihaya/chihaya/bittorrent"
 	"github.com/chihaya/chihaya/frontend"
 	"github.com/chihaya/chihaya/pkg/log"
 )
 
-func init() {
-	prometheus.MustRegister(promResponseDurationMilliseconds)
-}
-
-var promResponseDurationMilliseconds = prometheus.NewHistogramVec(
-	prometheus.HistogramOpts{
-		Name:    "chihaya_http_response_duration_milliseconds",
-		Help:    "The duration of time it takes to receive and write a response to an API request",
-		Buckets: prometheus.ExponentialBuckets(9.375, 2, 10),
-	},
-	[]string{"action", "address_family", "error"},
-)
-
-// recordResponseDuration records the duration of time to respond to a Request
-// in milliseconds .
-func recordResponseDuration(action string, af *bittorrent.AddressFamily, err error, duration time.Duration) {
-	var errString string
-	if err != nil {
-		if _, ok := err.(bittorrent.ClientError); ok {
-			errString = err.Error()
-		} else {
-			errString = "internal error"
-		}
-	}
-
-	var afString string
-	if af == nil {
-		afString = "Unknown"
-	} else if *af == bittorrent.IPv4 {
-		afString = "IPv4"
-	} else if *af == bittorrent.IPv6 {
-		afString = "IPv6"
-	}
-
-	promResponseDurationMilliseconds.
-		WithLabelValues(action, afString, errString).
-		Observe(float64(duration.Nanoseconds()) / float64(time.Millisecond))
-}
-
 // Config represents all of the configurable options for an HTTP BitTorrent
 // Frontend.
 type Config struct {

frontend/http/prometheus.go

@@ -0,0 +1,48 @@
+package http
+
+import (
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/chihaya/chihaya/bittorrent"
+)
+
+func init() {
+	prometheus.MustRegister(promResponseDurationMilliseconds)
+}
+
+var promResponseDurationMilliseconds = prometheus.NewHistogramVec(
+	prometheus.HistogramOpts{
+		Name:    "chihaya_http_response_duration_milliseconds",
+		Help:    "The duration of time it takes to receive and write a response to an API request",
+		Buckets: prometheus.ExponentialBuckets(9.375, 2, 10),
+	},
+	[]string{"action", "address_family", "error"},
+)
+
+// recordResponseDuration records the duration of time to respond to a Request
+// in milliseconds.
+func recordResponseDuration(action string, af *bittorrent.AddressFamily, err error, duration time.Duration) {
+	var errString string
+	if err != nil {
+		if _, ok := err.(bittorrent.ClientError); ok {
+			errString = err.Error()
+		} else {
+			errString = "internal error"
+		}
+	}
+
+	var afString string
+	if af == nil {
+		afString = "Unknown"
+	} else if *af == bittorrent.IPv4 {
+		afString = "IPv4"
+	} else if *af == bittorrent.IPv6 {
+		afString = "IPv6"
+	}
+
+	promResponseDurationMilliseconds.
+		WithLabelValues(action, afString, errString).
+		Observe(float64(duration.Nanoseconds()) / float64(time.Millisecond))
+}

frontend/udp/frontend.go

@@ -12,8 +12,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
-
 	"github.com/chihaya/chihaya/bittorrent"
 	"github.com/chihaya/chihaya/frontend"
 	"github.com/chihaya/chihaya/frontend/udp/bytepool"
@@ -24,45 +22,6 @@ import (
 
 var allowedGeneratedPrivateKeyRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
 
-func init() {
-	prometheus.MustRegister(promResponseDurationMilliseconds)
-}
-
-var promResponseDurationMilliseconds = prometheus.NewHistogramVec(
-	prometheus.HistogramOpts{
-		Name:    "chihaya_udp_response_duration_milliseconds",
-		Help:    "The duration of time it takes to receive and write a response to an API request",
-		Buckets: prometheus.ExponentialBuckets(9.375, 2, 10),
-	},
-	[]string{"action", "address_family", "error"},
-)
-
-// recordResponseDuration records the duration of time to respond to a UDP
-// Request in milliseconds .
-func recordResponseDuration(action string, af *bittorrent.AddressFamily, err error, duration time.Duration) {
-	var errString string
-	if err != nil {
-		if _, ok := err.(bittorrent.ClientError); ok {
-			errString = err.Error()
-		} else {
-			errString = "internal error"
-		}
-	}
-
-	var afString string
-	if af == nil {
-		afString = "Unknown"
-	} else if *af == bittorrent.IPv4 {
-		afString = "IPv4"
-	} else if *af == bittorrent.IPv6 {
-		afString = "IPv6"
-	}
-
-	promResponseDurationMilliseconds.
-		WithLabelValues(action, afString, errString).
-		Observe(float64(duration.Nanoseconds()) / float64(time.Millisecond))
-}
-
 // Config represents all of the configurable options for a UDP BitTorrent
 // Tracker.
 type Config struct {

frontend/udp/prometheus.go

@@ -0,0 +1,48 @@
+package udp
+
+import (
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/chihaya/chihaya/bittorrent"
+)
+
+func init() {
+	prometheus.MustRegister(promResponseDurationMilliseconds)
+}
+
+var promResponseDurationMilliseconds = prometheus.NewHistogramVec(
+	prometheus.HistogramOpts{
+		Name:    "chihaya_udp_response_duration_milliseconds",
+		Help:    "The duration of time it takes to receive and write a response to an API request",
+		Buckets: prometheus.ExponentialBuckets(9.375, 2, 10),
+	},
+	[]string{"action", "address_family", "error"},
+)
+
+// recordResponseDuration records the duration of time to respond to a UDP
+// Request in milliseconds.
+func recordResponseDuration(action string, af *bittorrent.AddressFamily, err error, duration time.Duration) {
+	var errString string
+	if err != nil {
+		if _, ok := err.(bittorrent.ClientError); ok {
+			errString = err.Error()
+		} else {
+			errString = "internal error"
+		}
+	}
+
+	var afString string
+	if af == nil {
+		afString = "Unknown"
+	} else if *af == bittorrent.IPv4 {
+		afString = "IPv4"
+	} else if *af == bittorrent.IPv6 {
+		afString = "IPv6"
+	}
+
+	promResponseDurationMilliseconds.
+		WithLabelValues(action, afString, errString).
+		Observe(float64(duration.Nanoseconds()) / float64(time.Millisecond))
+}