Add public function to graphite parser to apply template

services/graphite/parser.go

@@ -50,7 +50,9 @@ func NewParserWithOptions(options Options) (*Parser, error) {
 		filter := ""
 		// Format is [filter] <template> [tag1=value1,tag2=value2]
 		parts := strings.Fields(pattern)
-		if len(parts) >= 2 {
+		if len(parts) < 1 {
+			continue
+		} else if len(parts) >= 2 {
 			if strings.Contains(parts[1], "=") {
 				template = parts[0]
 			} else {
@@ -97,8 +99,8 @@ func (p *Parser) Parse(line string) (models.Point, error) {
 	}
 
 	// decode the name and tags
-	matcher := p.matcher.Match(fields[0])
-	measurement, tags := matcher.Apply(fields[0])
+	template := p.matcher.Match(fields[0])
+	measurement, tags := template.Apply(fields[0])
 
 	// Could not extract measurement, use the raw value
 	if measurement == "" {
@@ -145,6 +147,19 @@ func (p *Parser) Parse(line string) (models.Point, error) {
 	return point, nil
 }
 
+// Apply extracts the template fields form the given line and returns the
+// measurement name and tags
+func (p *Parser) ApplyTemplate(line string) (string, map[string]string) {
+	// Break line into fields (name, value, timestamp), only name is used
+	fields := strings.Fields(line)
+	if len(fields) == 0 {
+		return "", make(map[string]string)
+	}
+	// decode the name and tags
+	template := p.matcher.Match(fields[0])
+	return template.Apply(fields[0])
+}
+
 // template represents a pattern and tags to map a graphite metric string to a influxdb Point
 type template struct {
 	tags              []string

services/graphite/parser_test.go

@@ -546,3 +546,92 @@ func TestParseTemplateWhitespace(t *testing.T) {
 		t.Errorf("parse mismatch: got %v, exp %v", pt.String(), exp.String())
 	}
 }
+
+// Test basic functionality of ApplyTemplate
+func TestApplyTemplate(t *testing.T) {
+	o := graphite.Options{
+		Separator: "_",
+		Templates: []string{"current.* measurement.measurement"},
+	}
+	p, err := graphite.NewParserWithOptions(o)
+	if err != nil {
+		t.Fatalf("unexpected error creating parser, got %v", err)
+	}
+
+	measurement, _ := p.ApplyTemplate("current.users")
+	if measurement != "current_users" {
+		t.Errorf("Parser.ApplyTemplate unexpected result. got %s, exp %s",
+			measurement, "current_users")
+	}
+}
+
+// Test basic functionality of ApplyTemplate
+func TestApplyTemplateNoMatch(t *testing.T) {
+	o := graphite.Options{
+		Separator: "_",
+		Templates: []string{"foo.bar measurement.measurement"},
+	}
+	p, err := graphite.NewParserWithOptions(o)
+	if err != nil {
+		t.Fatalf("unexpected error creating parser, got %v", err)
+	}
+
+	measurement, _ := p.ApplyTemplate("current.users")
+	if measurement != "current.users" {
+		t.Errorf("Parser.ApplyTemplate unexpected result. got %s, exp %s",
+			measurement, "current.users")
+	}
+}
+
+// Test that most specific template is chosen
+func TestApplyTemplateSpecific(t *testing.T) {
+	o := graphite.Options{
+		Separator: "_",
+		Templates: []string{
+			"current.* measurement.measurement",
+			"current.*.* measurement.measurement.service",
+		},
+	}
+	p, err := graphite.NewParserWithOptions(o)
+	if err != nil {
+		t.Fatalf("unexpected error creating parser, got %v", err)
+	}
+
+	measurement, tags := p.ApplyTemplate("current.users.facebook")
+	if measurement != "current_users" {
+		t.Errorf("Parser.ApplyTemplate unexpected result. got %s, exp %s",
+			measurement, "current_users")
+	}
+	service, ok := tags["service"]
+	if !ok {
+		t.Error("Expected for template to apply a 'service' tag, but not found")
+	}
+	if service != "facebook" {
+		t.Errorf("Expected service='facebook' tag, got service='%s'", service)
+	}
+}
+
+func TestApplyTemplateTags(t *testing.T) {
+	o := graphite.Options{
+		Separator: "_",
+		Templates: []string{"current.* measurement.measurement region=us-west"},
+	}
+	p, err := graphite.NewParserWithOptions(o)
+	if err != nil {
+		t.Fatalf("unexpected error creating parser, got %v", err)
+	}
+
+	measurement, tags := p.ApplyTemplate("current.users")
+	if measurement != "current_users" {
+		t.Errorf("Parser.ApplyTemplate unexpected result. got %s, exp %s",
+			measurement, "current_users")
+	}
+
+	region, ok := tags["region"]
+	if !ok {
+		t.Error("Expected for template to apply a 'region' tag, but not found")
+	}
+	if region != "us-west" {
+		t.Errorf("Expected region='us-west' tag, got region='%s'", region)
+	}
+}