Add instrumentation with prometheus

lib/instrument/dummy.go

@@ -0,0 +1,14 @@
+// +build noprometheus
+
+package instrument
+
+import "time"
+
+type dummyInst struct{}
+
+func Init() Instrument {
+	return &dummyInst{}
+}
+
+func (i dummyInst) Visit(section string, id string, search string, fmt string) {}
+func (i dummyInst) Duration(section string, duration time.Duration)            {}

lib/instrument/instrument.go

@@ -0,0 +1,8 @@
+package instrument
+
+import "time"
+
+type Instrument interface {
+	Visit(section string, id string, search string, fmt string)
+	Duration(section string, duration time.Duration)
+}

lib/instrument/prometheus.go

@@ -0,0 +1,66 @@
+// +build !noprometheus
+
+package instrument
+
+import (
+	"time"
+
+	log "github.com/cihub/seelog"
+
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	promAddr = ":9123"
+)
+
+type promInst struct {
+	visits *prometheus.CounterVec
+	reqDur *prometheus.HistogramVec
+}
+
+func Init() Instrument {
+	go promHandle()
+
+	visits := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "trantor_visits_total",
+			Help: "Number of visits.",
+		},
+		[]string{"section", "id", "search", "fmt"},
+	)
+	reqDur := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name: "trantor_request_duration_seconds",
+			Help: "Duration of the request in seconds.",
+		},
+		[]string{"section"},
+	)
+
+	prometheus.MustRegister(visits)
+	prometheus.MustRegister(reqDur)
+
+	return &promInst{
+		visits: visits,
+		reqDur: reqDur,
+	}
+}
+
+func promHandle() {
+	server := http.Server{
+		Addr:    promAddr,
+		Handler: promhttp.Handler(),
+	}
+	log.Error(server.ListenAndServe())
+}
+
+func (in promInst) Visit(section string, id string, search string, fmt string) {
+	in.visits.WithLabelValues(section, id, search, fmt).Inc()
+}
+
+func (in promInst) Duration(section string, duration time.Duration) {
+	in.reqDur.WithLabelValues(section).Observe(duration.Seconds())
+}

lib/stats.go

@@ -5,14 +5,15 @@ import (
 
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/gorilla/mux"
 	"gitlab.com/trantor/trantor/lib/database"
+	"gitlab.com/trantor/trantor/lib/instrument"
 	"gitlab.com/trantor/trantor/lib/storage"
 )
 
 const (
-	stats_version = 2
 	statsChanSize = 100
 )
 
@@ -28,22 +29,26 @@ type handler struct {
 }
 
 type StatsGatherer struct {
-	db       database.DB
-	store    storage.Store
-	template *Template
-	hostname string
-	channel  chan statsRequest
-	ro       bool
+	db         database.DB
+	store      storage.Store
+	template   *Template
+	instrument instrument.Instrument
+	hostname   string
+	channel    chan statsRequest
+	ro         bool
 }
 
 func InitStats(database database.DB, store storage.Store, hostname string, template *Template, ro bool) *StatsGatherer {
+	in := instrument.Init()
+
 	sg := StatsGatherer{
-		channel:  make(chan statsRequest, statsChanSize),
-		db:       database,
-		store:    store,
-		template: template,
-		hostname: hostname,
-		ro:       ro,
+		channel:    make(chan statsRequest, statsChanSize),
+		db:         database,
+		store:      store,
+		instrument: in,
+		template:   template,
+		hostname:   hostname,
+		ro:         ro,
 	}
 
 	go sg.worker()
@@ -65,33 +70,42 @@ func (sg StatsGatherer) Gather(function func(handler)) func(http.ResponseWriter,
 			ro:       sg.ro,
 		}
 
+		t0 := time.Now()
 		function(h)
-		sg.channel <- statsRequest{r}
+		t1 := time.Now()
+		sg.channel <- statsRequest{r, t1.Sub(t0)}
 	}
 }
 
 type statsRequest struct {
-	r *http.Request
+	r        *http.Request
+	duration time.Duration
 }
 
 func (sg StatsGatherer) worker() {
 	for req := range sg.channel {
 		var err error
-		pattern := strings.Split(req.r.URL.Path, "/")
 		id := mux.Vars(req.r)["id"]
-		if len(pattern) > 1 && pattern[1] != "" && id != "" {
-			switch pattern[1] {
-			case "download":
-				id := mux.Vars(req.r)["id"]
-				err = sg.db.IncDownloads(id)
-			case "book":
-				id := mux.Vars(req.r)["id"]
-				err = sg.db.IncViews(id)
-			case "read":
-				id := mux.Vars(req.r)["id"]
-				err = sg.db.IncViews(id)
-			}
+		search := strings.Join(req.r.Form["q"], " ")
+		fmt := req.r.FormValue("fmt")
+		pattern := strings.Split(req.r.URL.Path, "/")
+
+		section := "/"
+		if len(pattern) > 1 && pattern[1] != "" {
+			section = pattern[1]
 		}
+
+		sg.instrument.Visit(section, id, search, fmt)
+		sg.instrument.Duration(section, req.duration*time.Microsecond)
+		switch section {
+		case "download":
+			err = sg.db.IncDownloads(id)
+		case "book":
+			err = sg.db.IncViews(id)
+		case "read":
+			err = sg.db.IncViews(id)
+		}
+
 		if err != nil {
 			log.Warn("Problem incrementing visits: ", err)
 		}

lib/trantor.go

@@ -152,7 +152,7 @@ func UpdateLogger(loggerConfig string) error {
 	return log.ReplaceLogger(logger)
 }
 
-func InitRouter(db database.DB, sg *StatsGatherer, assetsPath string) {
+func InitRouter(db database.DB, sg *StatsGatherer, assetsPath string) http.Handler {
 	const idPattern = "[0-9a-zA-Z\\-\\_]{16}"
 
 	r := mux.NewRouter()
@@ -203,7 +203,7 @@ func InitRouter(db database.DB, sg *StatsGatherer, assetsPath string) {
 	r.HandleFunc("/news/edit", sg.Gather(editNewsHandler)).Methods("GET")
 	r.HandleFunc("/news/edit", sg.Gather(postNewsHandler)).Methods("POST")
 
-	http.Handle("/", r)
+	return r
 }
 
 func fileServer(servePath string, prefix string) func(w http.ResponseWriter, r *http.Request) {

main.go

@@ -62,6 +62,10 @@ func main() {
 	trantor.InitUpload(db, store)
 	trantor.InitTasks(db, *loggerConfig)
 
-	trantor.InitRouter(db, sg, *assetsPath)
-	log.Error(http.ListenAndServe(*httpAddr, nil))
+	router := trantor.InitRouter(db, sg, *assetsPath)
+	server := http.Server{
+		Addr:    *httpAddr,
+		Handler: router,
+	}
+	log.Error(server.ListenAndServe())
 }