Fix things commented on in past code review.

Change-Id: I4dafd098eefa99bc37fdbfebeb4c61a7251ad0be

prometheus/registry.go

@@ -23,7 +23,6 @@ import (
 	dto "github.com/prometheus/client_model/go"
 
 	"code.google.com/p/goprotobuf/proto"
-	"github.com/matttproud/golang_protobuf_extensions/ext"
 
 	"github.com/prometheus/client_golang/model"
 	"github.com/prometheus/client_golang/text"
@@ -43,11 +42,11 @@ const (
 	jsonContentType          = "application/json"
 )
 
-// encoder is a function that writes a proto.Message to an io.Writer in a
+// encoder is a function that writes a dto.MetricFamily to an io.Writer in a
 // certain encoding. It returns the number of bytes written and any error
 // encountered.  Note that ext.WriteDelimited and text.MetricFamilyToText are
 // encoders.
-type encoder func(io.Writer, proto.Message) (int, error)
+type encoder func(io.Writer, *dto.MetricFamily) (int, error)
 
 // container represents a top-level registered metric that encompasses its
 // static metadata.
@@ -341,7 +340,7 @@ func (r *registry) Handler() http.HandlerFunc {
 				switch accept.Params["encoding"] {
 				case "delimited":
 					header.Set(contentTypeHeader, DelimitedTelemetryContentType)
-					enc = ext.WriteDelimited
+					enc = text.WriteProtoDelimited
 				case "text":
 					header.Set(contentTypeHeader, ProtoTextTelemetryContentType)
 					enc = text.WriteProtoText

text/create.go

@@ -25,7 +25,6 @@ import (
 	"fmt"
 	"io"
 	"strings"
-	"code.google.com/p/goprotobuf/proto"
 
 	dto "github.com/prometheus/client_model/go"
 )
@@ -35,33 +34,33 @@ import (
 // and any error encountered.  This function does not perform checks on the
 // content of the metric and label names, i.e. invalid metric or label names
 // will result in invalid text format output.
-func MetricFamilyToText(out io.Writer, in proto.Message) (int, error) {
-	mf := in.(*dto.MetricFamily)
+// This method fulfills the type 'prometheus.encoder'.
+func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 	var written int
 
 	// Fail-fast checks.
-	if len(mf.Metric) == 0 {
+	if len(in.Metric) == 0 {
 		return written, fmt.Errorf("MetricFamily has no metrics: %s", in)
 	}
-	name := mf.GetName()
+	name := in.GetName()
 	if name == "" {
 		return written, fmt.Errorf("MetricFamily has no name: %s", in)
 	}
-	if mf.Type == nil {
+	if in.Type == nil {
 		return written, fmt.Errorf("MetricFamily has no type: %s", in)
 	}
 
 	// Comments, first HELP, then TYPE.
-	if mf.Help != nil {
+	if in.Help != nil {
 		n, err := fmt.Fprintf(
 			out, "# HELP %s %s\n",
-			name, strings.Replace(*mf.Help, "\n", `\n`, -1))
+			name, strings.Replace(*in.Help, "\n", `\n`, -1))
 		written += n
 		if err != nil {
 			return written, err
 		}
 	}
-	metricType := mf.GetType()
+	metricType := in.GetType()
 	n, err := fmt.Fprintf(
 		out, "# TYPE %s %s\n",
 		name, strings.ToLower(metricType.String()),
@@ -72,7 +71,7 @@ func MetricFamilyToText(out io.Writer, in proto.Message) (int, error) {
 	}
 
 	// Finally the samples, one line for each.
-	for _, metric := range mf.Metric {
+	for _, metric := range in.Metric {
 		switch metricType {
 		case dto.MetricType_COUNTER:
 			if metric.Counter == nil {

text/proto.go

@@ -18,16 +18,26 @@ import (
 	"io"
 
 	"code.google.com/p/goprotobuf/proto"
+	"github.com/matttproud/golang_protobuf_extensions/ext"
+
+	dto "github.com/prometheus/client_model/go"
 )
 
-// WriteProtoText writes the proto.Message to the writer in text format and
+// WriteProtoDelimited writes the MetricFamily to the writer in delimited
+// protobuf format and returns the number of bytes written and any error
+// encountered.
+func WriteProtoDelimited(w io.Writer, p *dto.MetricFamily) (int, error) {
+	return ext.WriteDelimited(w, p)
+}
+
+// WriteProtoText writes the MetricFamily to the writer in text format and
 // returns the number of bytes written and any error encountered.
-func WriteProtoText(w io.Writer, p proto.Message) (int, error) {
+func WriteProtoText(w io.Writer, p *dto.MetricFamily) (int, error) {
 	return fmt.Fprintf(w, "%s\n", proto.MarshalTextString(p))
 }
 
-// WriteProtoCompactText writes the proto.Message to the writer in compact text
+// WriteProtoCompactText writes the MetricFamily to the writer in compact text
 // format and returns the number of bytes written and any error encountered.
-func WriteProtoCompactText(w io.Writer, p proto.Message) (int, error) {
+func WriteProtoCompactText(w io.Writer, p *dto.MetricFamily) (int, error) {
 	return fmt.Fprintf(w, "%s\n", p)
 }