refactor: put prometheus metrics in own namespace

doc.go

@@ -66,7 +66,7 @@ Timeseries queries return values as a list of timestamp/value tuples. Here's an
 
 Table Queries
 
-Table Queries, on the other hand, return data organized in columns & rows.  Each column needs to have the same number of rows:
+Table Queries, on the other hand, return data organized in columns and rows.  Each column needs to have the same number of rows:
 
 	func (handler *myHandler) TableQuery(_ context.Context, _ string, _ *simplejson.TableQueryArgs) (response *simplejson.QueryResponse, err error) {
 		response = &simplejson.TableQueryResponse{
@@ -80,6 +80,13 @@ Table Queries, on the other hand, return data organized in columns & rows.  Each
 		return
 	}
 
+Metrics
+
+simplejson exports two Prometheus metrics for performance analytics:
+
+	simplejson_query_duration_seconds: duration of query requests by target, in seconds
+	simplejson_query_failed_count:     number of failed query requests
+
 Other topics
 
 For information on query arguments, annotation and tags, refer to the documentation for those data structures.

doc_test.go

@@ -0,0 +1,66 @@
+package simplejson_test
+
+import (
+	"context"
+	"github.com/clambin/simplejson"
+	"time"
+)
+
+type handler struct{}
+
+func (h handler) Endpoints() simplejson.Endpoints {
+	return simplejson.Endpoints{
+		Query:      h.Query,
+		TableQuery: h.TableQuery,
+	}
+}
+
+func (h *handler) Query(_ context.Context, _ *simplejson.TimeSeriesQueryArgs) (response *simplejson.TimeSeriesResponse, err error) {
+	response = &simplejson.TimeSeriesResponse{
+		DataPoints: make([]simplejson.DataPoint, 60),
+	}
+
+	timestamp := time.Now().Add(-1 * time.Hour)
+	for i := 0; i < 60; i++ {
+		response.DataPoints[i] = simplejson.DataPoint{
+			Timestamp: timestamp,
+			Value:     int64(i),
+		}
+		timestamp = timestamp.Add(1 * time.Minute)
+	}
+	return
+}
+
+func (h *handler) TableQuery(_ context.Context, _ *simplejson.TableQueryArgs) (response *simplejson.TableQueryResponse, err error) {
+	timestamps := make(simplejson.TableQueryResponseTimeColumn, 60)
+	seriesA := make(simplejson.TableQueryResponseNumberColumn, 60)
+	seriesB := make(simplejson.TableQueryResponseNumberColumn, 60)
+
+	timestamp := time.Now().Add(-1 * time.Hour)
+	for i := 0; i < 60; i++ {
+		timestamps[i] = timestamp
+		seriesA[i] = float64(i)
+		seriesB[i] = float64(-i)
+		timestamp = timestamp.Add(1 * time.Minute)
+	}
+
+	response = &simplejson.TableQueryResponse{
+		Columns: []simplejson.TableQueryResponseColumn{
+			{Text: "timestamp", Data: timestamps},
+			{Text: "series A", Data: seriesA},
+			{Text: "series B", Data: seriesB},
+		},
+	}
+
+	return
+}
+
+func Example() {
+	s := simplejson.Server{
+		Handlers: map[string]simplejson.Handler{
+			"A": &handler{},
+		},
+	}
+
+	_ = s.Run(8088)
+}

endpoint.go

@@ -15,7 +15,6 @@ func handleEndpoint(w http.ResponseWriter, req *http.Request, request interface{
 			err = json.Unmarshal(body, &request)
 		}
 	}
-	_ = req.Body.Close()
 
 	if err != nil {
 		http.Error(w, "failed to parse request: "+err.Error(), http.StatusBadRequest)

ep_query.go

@@ -11,12 +11,12 @@ import (
 )
 
 var queryDuration = promauto.NewSummaryVec(prometheus.SummaryOpts{
-	Name: "grafana_api_query_duration_seconds",
+	Name: prometheus.BuildFQName("simplejson", "query", "duration_seconds"),
 	Help: "Grafana SimpleJSON server duration of query requests by target",
 }, []string{"app", "type", "target"})
 
 var queryFailure = promauto.NewCounterVec(prometheus.CounterOpts{
-	Name: "grafana_api_query_failed_count",
+	Name: prometheus.BuildFQName("simplejson", "query", "failed_count"),
 	Help: "Grafana SimpleJSON server count of failed requests",
 }, []string{"app", "type", "target"})
 

testserver/testserver.go

@@ -18,7 +18,7 @@ func main() {
 
 type handler struct{}
 
-func (h *handler) Endpoints() simplejson.Endpoints {
+func (h handler) Endpoints() simplejson.Endpoints {
 	return simplejson.Endpoints{
 		Query:       h.Query,
 		TableQuery:  h.TableQuery,