store metric units in a fixed tag (hawkular#58)

collector/manager/metrics_collector_manager.go

@@ -182,8 +182,18 @@ func (mcm *MetricsCollectorManager) declareMetricDefinitions(liveMetrics []hmetr
 			}
 		}
 
+		// the metric tags will consist of the custom tags as well as the fixed tags
 		metricTags := metric.Tags.ExpandTokens(false, additionalEnv)
+		units, err := collector.GetMetricUnits(metric.Units)
+		if err == nil {
+			if units.Symbol != "" {
+				metricTags["units"] = units.Symbol
+			}
+		} else {
+			glog.Warningf("Units for metric definition [%v] for endpoint [%v] is invalid. No units will be assigned. err=%v", metric.ID, endpoint.String(), err)
+		}
 
+		// put all the tags together for the full list of tags to be applied to this metric definition
 		allMetricTags := tags.Tags{}
 		allMetricTags.AppendTags(globalTags)   // global tags are overridden by...
 		allMetricTags.AppendTags(endpointTags) // endpoint tags which are overridden by...

collector/metric_units.go

@@ -0,0 +1,109 @@
+package collector
+
+import (
+	"fmt"
+	"strings"
+)
+
+type MetricUnits struct {
+	Symbol string
+	Custom bool
+}
+
+const customMetricUnitsPrefix = "custom:"
+
+type standardMetricUnits []MetricUnits
+
+// standardMetricUnitsList is a list of standard metric units
+// See https://en.wikipedia.org/wiki/International_System_of_Units and http://metrics20.org/spec/
+var standardMetricUnitsList = standardMetricUnits{
+	// absolute sizes in bytes
+	{Symbol: "B"},
+	{Symbol: "kB"},
+	{Symbol: "MB"},
+	{Symbol: "GB"},
+	{Symbol: "TB"},
+	{Symbol: "PB"},
+	{Symbol: "KiB"},
+	{Symbol: "MiB"},
+	{Symbol: "GiB"},
+	{Symbol: "TiB"},
+	{Symbol: "PiB"},
+
+	// absolute sizes in bits
+	{Symbol: "b"},
+	{Symbol: "kb"},
+	{Symbol: "Mb"},
+	{Symbol: "Gb"},
+	{Symbol: "Tb"},
+	{Symbol: "Pb"},
+	{Symbol: "Kib"},
+	{Symbol: "Mib"},
+	{Symbol: "Gib"},
+	{Symbol: "Tib"},
+	{Symbol: "Pib"},
+
+	// relative time
+	{Symbol: "jiff"},
+	{Symbol: "ns"},
+	{Symbol: "us"},
+	{Symbol: "ms"},
+	{Symbol: "s"},
+	{Symbol: "M"},
+	{Symbol: "h"},
+	{Symbol: "d"},
+	{Symbol: "w"},
+
+	// frequency
+	{Symbol: "Hz"},
+	{Symbol: "kHz"},
+	{Symbol: "MHz"},
+	{Symbol: "GHz"},
+
+	// temperature
+	{Symbol: "C"},
+	{Symbol: "F"},
+	{Symbol: "K"},
+
+	// current
+	{Symbol: "uA"},
+	{Symbol: "mA"},
+	{Symbol: "A"},
+	{Symbol: "kA"},
+	{Symbol: "MA"},
+	{Symbol: "GA"},
+
+	// voltage
+	{Symbol: "uV"},
+	{Symbol: "mV"},
+	{Symbol: "V"},
+	{Symbol: "kV"},
+	{Symbol: "MV"},
+	{Symbol: "GV"},
+
+	// percentage
+	{Symbol: "%"},
+
+	// none (no metric units are applicable)
+	{Symbol: ""},
+}
+
+// GetMetricUnits will check to see if the given string is a valid units identifier.
+// If it is valid, this returns the units string as a MetricUnits.
+// If it is not a valid units identifier, an error is returned.
+// If it is a custom units identifier, it is returned minus the custom units prefix.
+func GetMetricUnits(u string) (MetricUnits, error) {
+	if len(u) > len(customMetricUnitsPrefix) && strings.HasPrefix(u, customMetricUnitsPrefix) {
+		mu := MetricUnits{
+			Symbol: strings.TrimPrefix(u, customMetricUnitsPrefix),
+			Custom: true,
+		}
+		return mu, nil
+	}
+	for _, x := range standardMetricUnitsList {
+		if x.Symbol == u {
+			return x, nil
+		}
+	}
+	return MetricUnits{}, fmt.Errorf("invalid metric units: %v", u)
+}

collector/metric_units_test.go

@@ -0,0 +1,51 @@
+package collector
+
+import (
+	"testing"
+)
+
+func TestGetMetricUnits(t *testing.T) {
+	// make sure valid metrics are retrieved successfully
+	u, e := GetMetricUnits("ms")
+	if e != nil {
+		t.Errorf("Should not have failed. Error=%v", e)
+	}
+	if u.Symbol != "ms" {
+		t.Errorf("Should have matched 'ms'. u=%v", u)
+	}
+	if u.Custom != false {
+		t.Errorf("Should not have been custom. u=%v", u)
+	}
+
+	u, e = GetMetricUnits("custom:foobars")
+	if e != nil {
+		t.Errorf("Should not have failed. Error=%v", e)
+	}
+	if u.Symbol != "foobars" {
+		t.Errorf("Should have matched 'foobars'. u=%v", u)
+	}
+	if u.Custom != true {
+		t.Errorf("Should have been custom. u=%v", u)
+	}
+
+	u, e = GetMetricUnits("")
+	if e != nil {
+		t.Errorf("Should not have failed. Empty units means 'none'. Error=%v", e)
+	}
+	if u.Symbol != "" {
+		t.Errorf("Should have matched the 'none' units (an empty string). u=%v", u)
+	}
+	if u.Custom != false {
+		t.Errorf("Should not have been custom. u=%v", u)
+	}
+
+	// make sure errors are generated properly
+	u, e = GetMetricUnits("millis")
+	if e == nil {
+		t.Errorf("Should have failed - not a standard metric. u=%v", u)
+	}
+	u, e = GetMetricUnits("foobars")
+	if e == nil {
+		t.Errorf("Should have failed - not a standard metric. u=%v", u)
+	}
+}

collector/metrics_endpoint.go

@@ -41,10 +41,11 @@ const (
 // Tags specified here will be attached to the metric when stored to Hawkular Metrics.
 // USED FOR YAML
 type MonitoredMetric struct {
-	ID   string ",omitempty"
-	Name string
-	Type metrics.MetricType
-	Tags tags.Tags ",omitempty"
+	ID    string ",omitempty"
+	Name  string
+	Type  metrics.MetricType
+	Units string    ",omitempty"
+	Tags  tags.Tags ",omitempty"
 }
 
 // Endpoint provides information about how to connect to a particular endpoint in order
@@ -64,7 +65,7 @@ type Endpoint struct {
 }
 
 func (m *MonitoredMetric) String() string {
-	return fmt.Sprintf("Metric: id=[%v], name=[%v], type=[%v], tags=[%v]", m.ID, m.Name, m.Type, m.Tags)
+	return fmt.Sprintf("Metric: id=[%v], name=[%v], type=[%v], units=[%v], tags=[%v]", m.ID, m.Name, m.Type, m.Units, m.Tags)
 }
 
 func (e *Endpoint) String() string {
@@ -115,6 +116,10 @@ func (e *Endpoint) ValidateEndpoint() error {
 			}
 		}
 
+		if _, err := GetMetricUnits(m.Units); err != nil {
+			return fmt.Errorf("Endpoint [%v] metric [%v] has invalid units [%v]", e.URL, m.Name, m.Units)
+		}
+
 		// if there is no metric ID given, just use the metric name itself
 		if m.ID == "" {
 			e.Metrics[i].ID = m.Name