From a2af521aa2b51d22abc230cf22b2bb9d5b897aa2 Mon Sep 17 00:00:00 2001
From: "Ric (Ryszard) Szopa" <ryszard.szopa@gmail.com>
Date: Thu, 25 Feb 2016 16:46:12 +0100
Subject: [PATCH] Add Prometheus instrumentation to the client.

---
 go/client/doorman/client.go | 44 +++++++++++++++++++++++++++++++++++++
 go/connection/connection.go |  4 ++++
 2 files changed, 48 insertions(+)

diff --git a/go/client/doorman/client.go b/go/client/doorman/client.go
index fbd06ea..9753f76 100644
--- a/go/client/doorman/client.go
+++ b/go/client/doorman/client.go
@@ -31,6 +31,7 @@ import (
 
 	log "github.com/golang/glog"
 	"github.com/golang/protobuf/proto"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/youtube/doorman/go/connection"
 	"github.com/youtube/doorman/go/timeutil"
 	"golang.org/x/net/context"
@@ -65,6 +66,37 @@ var (
 	ErrInvalidWants = errors.New("wants must be > 0.0")
 )
 
+var (
+	requestLabels = []string{"server", "method"}
+
+	requests = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "doorman",
+		Subsystem: "client",
+		Name:      "requests",
+		Help:      "Requests sent to a Doorman service.",
+	}, requestLabels)
+
+	requestErrors = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "doorman",
+		Subsystem: "client",
+		Name:      "request_errors",
+		Help:      "Requests sent to a Doorman service that returned an error.",
+	}, requestLabels)
+
+	requestDurations = prometheus.NewHistogramVec(prometheus.HistogramOpts{
+		Namespace: "doorman",
+		Subsystem: "client",
+		Name:      "request_durations",
+		Help:      "Duration of different requests in seconds.",
+	}, requestLabels)
+)
+
+func init() {
+	prometheus.MustRegister(requests)
+	prometheus.MustRegister(requestErrors)
+	prometheus.MustRegister(requestDurations)
+}
+
 // NOTE: We're wrapping connection package's functions and types here in the client,
 // because we do not want our users to be aware of the internal connection package.
 
@@ -405,12 +437,17 @@ func (client *Client) Close() {
 func (client *Client) releaseCapacity(in *pb.ReleaseCapacityRequest) (*pb.ReleaseCapacityResponse, error) {
 	// context.TODO(ryszard): Plumb a context through.
 	out, err := client.conn.ExecuteRPC(func() (connection.HasMastership, error) {
+		start := time.Now()
+		requests.WithLabelValues(client.conn.String(), "ReleaseCapacity").Inc()
+		defer requestDurations.WithLabelValues(client.conn.String(), "ReleaseCapacity").Observe(time.Since(start).Seconds())
+
 		return client.conn.Stub.ReleaseCapacity(context.TODO(), in)
 
 	})
 
 	// Returns an error if we could not execute the RPC.
 	if err != nil {
+		requestErrors.WithLabelValues(client.conn.String(), "ReleaseCapacity").Inc()
 		return nil, err
 	}
 
@@ -423,12 +460,19 @@ func (client *Client) releaseCapacity(in *pb.ReleaseCapacityRequest) (*pb.Releas
 func (client *Client) getCapacity(in *pb.GetCapacityRequest) (*pb.GetCapacityResponse, error) {
 	// context.TODO(ryszard): Plumb a context through.
 	out, err := client.conn.ExecuteRPC(func() (connection.HasMastership, error) {
+		start := time.Now()
+		requests.WithLabelValues(client.conn.String(), "GetCapacity").Inc()
+		defer func() {
+			log.Infof("%v %v", time.Since(start).Seconds(), time.Since(start))
+			requestDurations.WithLabelValues(client.conn.String(), "GetCapacity").Observe(time.Since(start).Seconds())
+		}()
 		return client.conn.Stub.GetCapacity(context.TODO(), in)
 
 	})
 
 	// Returns an error if we could not execute the RPC.
 	if err != nil {
+		requestErrors.WithLabelValues(client.conn.String(), "GetCapacity").Inc()
 		return nil, err
 	}
 
diff --git a/go/connection/connection.go b/go/connection/connection.go
index 25fd087..5eb9008 100644
--- a/go/connection/connection.go
+++ b/go/connection/connection.go
@@ -46,6 +46,10 @@ type Connection struct {
 	Opts          *Options
 }
 
+func (connection *Connection) String() string {
+	return connection.currentMaster
+}
+
 // New creates a new Connection with the given server address.
 func New(addr string, options ...Option) (*Connection, error) {
 	connection := &Connection{