Export LabelsFromName func from CollectD receiver (open-telemetry#117)

* Export LabelsFromName func from CollectD receiver

Exporting this function since it can be useful in other cases that parse
text metrics that embedded collectd tags.

* Gofmt modified file

receiver/collectdreceiver/collectd.go

@@ -194,7 +194,7 @@ func (r *collectDRecord) pointTypeInstance(attrs map[string]string, parts []byte
  return parts
  }
 
- instanceName, extractedAttrs := labelsFromName(r.TypeInstance)
+ instanceName, extractedAttrs := LabelsFromName(r.TypeInstance)
  if instanceName != "" {
  if len(parts) > 0 {
  parts = append(parts, '.')
@@ -210,13 +210,16 @@ func (r *collectDRecord) pointTypeInstance(attrs map[string]string, parts []byte
  return parts
 }
 
-// labelsFromName tries to pull out dimensions out of name in the format name[k=v,f=x]-morename
-// would return name-morename and extract dimensions (k,v) and (f,x)
-// if we encounter something we don't expect use original name.
-// This is a bit complicated to avoid allocations, string.split allocates, while slices
-// inside same function, do not.
-func labelsFromName(val *string) (instanceName string, toAddDims map[string]string) {
- instanceName = *val
+// LabelsFromName tries to pull out dimensions out of name in the format
+// "name[k=v,f=x]-more_name".
+// For the example above it would return "name-more_name" and extract dimensions
+// (k,v) and (f,x).
+// If something unexpected is encountered it returns the original metric name.
+//
+// The code tries to avoid allocation by using local slices and avoiding calls
+// to functions like strings.Slice.
+func LabelsFromName(val *string) (metricName string, labels map[string]string) {
+ metricName = *val
  index := strings.Index(*val, "[")
  if index > -1 {
  left := (*val)[:index]
@@ -244,8 +247,8 @@ func labelsFromName(val *string) (instanceName string, toAddDims map[string]stri
  prev = cindex + 1
  cindex = strings.Index(dimensions[prev:], ",") + prev
  }
- toAddDims = working
- instanceName = left + rest
+ labels = working
+ metricName = left + rest
  }
  }
  return
@@ -267,7 +270,7 @@ func parseAndAddLabels(labels map[string]string, pluginInstance *string, host *s
 }
 
 func parseNameForLabels(labels map[string]string, key string, val *string) {
- instanceName, toAddDims := labelsFromName(val)
+ instanceName, toAddDims := LabelsFromName(val)
 
  for k, v := range toAddDims {
  if _, exists := labels[k]; !exists {

receiver/collectdreceiver/collectd_test.go

@@ -384,3 +384,52 @@ var wantMetricsData = []*metricspb.Metric{
  },
  },
 }
+
+func TestLabelsFromName(t *testing.T) {
+ tests := []struct {
+ name string
+ wantMetricName string
+ wantLabels map[string]string
+ }{
+ {
+ name: "simple",
+ wantMetricName: "simple",
+ },
+ {
+ name: "single[k=v]",
+ wantMetricName: "single",
+ wantLabels: map[string]string{
+ "k": "v",
+ },
+ },
+ {
+ name: "a.b.c.[k=v].d",
+ wantMetricName: "a.b.c..d",
+ wantLabels: map[string]string{
+ "k": "v",
+ },
+ },
+ {
+ name: "a.b[k0=v0,k1=v1,k2=v2].c",
+ wantMetricName: "a.b.c",
+ wantLabels: map[string]string{
+ "k0": "v0", "k1": "v1", "k2": "v2",
+ },
+ },
+ {
+ name: "empty[]",
+ wantMetricName: "empty[]",
+ },
+ {
+ name: "mal.formed[k_no_sep]",
+ wantMetricName: "mal.formed[k_no_sep]",
+ },
+ }
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ gotMetricName, gotLabels := LabelsFromName(&tt.name)
+ assert.Equal(t, tt.wantMetricName, gotMetricName)
+ assert.Equal(t, tt.wantLabels, gotLabels)
+ })
+ }
+}