feature: introduces diff and non_negative_diff into BasicStats Aggregator plugin

plugins/aggregators/basicstats/README.md

@@ -1,6 +1,6 @@
 # BasicStats Aggregator Plugin
 
-The BasicStats aggregator plugin give us count,max,min,mean,sum,s2(variance), stdev for a set of values,
+The BasicStats aggregator plugin give us count,diff,max,min,mean,non_negative_diff,sum,s2(variance), stdev for a set of values,
 emitting the aggregate every `period` seconds.
 
 ### Configuration:
@@ -15,20 +15,22 @@ emitting the aggregate every `period` seconds.
   drop_original = false
 
   ## Configures which basic stats to push as fields
-  # stats = ["count", "min", "max", "mean", "stdev", "s2", "sum"]
+  # stats = ["count","diff","min","max","mean","non_negative_diff","stdev","s2","sum"]
 ```
 
 - stats
-    - If not specified, then `count`, `min`, `max`, `mean`, `stdev`, and `s2` are aggregated and pushed as fields.  `sum` is not aggregated by default to maintain backwards compatibility.
+    - If not specified, then `count`, `min`, `max`, `mean`, `stdev`, and `s2` are aggregated and pushed as fields.  `sum`, `diff` and `non_negative_diff` are not aggregated by default to maintain backwards compatibility.
     - If empty array, no stats are aggregated
 
 ### Measurements & Fields:
 
 - measurement1
     - field1_count
+    - field1_diff (difference)
     - field1_max
     - field1_min
     - field1_mean
+    - field1_non_negative_diff (non-negative difference)
     - field1_sum
     - field1_s2 (variance)
     - field1_stdev (standard deviation)
@@ -43,8 +45,8 @@ No tags are applied by this aggregator.
 $ telegraf --config telegraf.conf --quiet
 system,host=tars load1=1 1475583980000000000
 system,host=tars load1=1 1475583990000000000
-system,host=tars load1_count=2,load1_max=1,load1_min=1,load1_mean=1,load1_sum=2,load1_s2=0,load1_stdev=0 1475584010000000000
+system,host=tars load1_count=2,load1_diff=0,load1_max=1,load1_min=1,load1_mean=1,load1_sum=2,load1_s2=0,load1_stdev=0 1475584010000000000
 system,host=tars load1=1 1475584020000000000
 system,host=tars load1=3 1475584030000000000
-system,host=tars load1_count=2,load1_max=3,load1_min=1,load1_mean=2,load1_sum=4,load1_s2=2,load1_stdev=1.414162 1475584010000000000
+system,host=tars load1_count=2,load1_diff=2,load1_max=3,load1_min=1,load1_mean=2,load1_sum=4,load1_s2=2,load1_stdev=1.414162 1475584010000000000
 ```

plugins/aggregators/basicstats/basicstats.go

@@ -16,13 +16,15 @@ type BasicStats struct {
 }
 
 type configuredStats struct {
-	count    bool
-	min      bool
-	max      bool
-	mean     bool
-	variance bool
-	stdev    bool
-	sum      bool
+	count             bool
+	min               bool
+	max               bool
+	mean              bool
+	variance          bool
+	stdev             bool
+	sum               bool
+	diff              bool
+	non_negative_diff bool
 }
 
 func NewBasicStats() *BasicStats {
@@ -43,7 +45,9 @@ type basicstats struct {
 	max   float64
 	sum   float64
 	mean  float64
-	M2    float64 //intermedia value for variance/stdev
+	diff  float64
+	M2    float64 //intermediate value for variance/stdev
+	LAST  float64 //intermediate value for diff
 }
 
 var sampleConfig = `
@@ -82,7 +86,9 @@ func (m *BasicStats) Add(in telegraf.Metric) {
 					max:   fv,
 					mean:  fv,
 					sum:   fv,
+					diff:  0.0,
 					M2:    0.0,
+					LAST:  fv,
 				}
 			}
 		}
@@ -98,7 +104,9 @@ func (m *BasicStats) Add(in telegraf.Metric) {
 						max:   fv,
 						mean:  fv,
 						sum:   fv,
+						diff:  0.0,
 						M2:    0.0,
+						LAST:  fv,
 					}
 					continue
 				}
@@ -127,6 +135,8 @@ func (m *BasicStats) Add(in telegraf.Metric) {
 				}
 				//sum compute
 				tmp.sum += fv
+				//diff compute
+				tmp.diff = fv - tmp.LAST
 				//store final data
 				m.cache[id].fields[field.Key] = tmp
 			}
@@ -167,6 +177,13 @@ func (m *BasicStats) Push(acc telegraf.Accumulator) {
 				if config.stdev {
 					fields[k+"_stdev"] = math.Sqrt(variance)
 				}
+				if config.diff {
+					fields[k+"_diff"] = v.diff
+				}
+				if config.non_negative_diff && v.diff >= 0 {
+					fields[k+"_non_negative_diff"] = v.diff
+				}
+
 			}
 			//if count == 1 StdDev = infinite => so I won't send data
 		}
@@ -199,6 +216,10 @@ func parseStats(names []string) *configuredStats {
 			parsed.stdev = true
 		case "sum":
 			parsed.sum = true
+		case "diff":
+			parsed.diff = true
+		case "non_negative_diff":
+			parsed.non_negative_diff = true
 
 		default:
 			log.Printf("W! Unrecognized basic stat '%s', ignoring", name)
@@ -219,6 +240,7 @@ func defaultStats() *configuredStats {
 	defaults.variance = true
 	defaults.stdev = true
 	defaults.sum = false
+	defaults.non_negative_diff = false
 
 	return defaults
 }

plugins/aggregators/basicstats/basicstats_test.go

@@ -17,6 +17,7 @@ var m1, _ = metric.New("m1",
 		"b": int64(1),
 		"c": float64(2),
 		"d": float64(2),
+		"g": int64(3),
 	},
 	time.Now(),
 )
@@ -31,6 +32,7 @@ var m2, _ = metric.New("m1",
 		"f":        uint64(200),
 		"ignoreme": "string",
 		"andme":    true,
+		"g":        int64(1),
 	},
 	time.Now(),
 )
@@ -86,6 +88,12 @@ func TestBasicStatsWithPeriod(t *testing.T) {
 		"f_max":   float64(200),
 		"f_min":   float64(200),
 		"f_mean":  float64(200),
+		"g_count": float64(2), //g
+		"g_max":   float64(3),
+		"g_min":   float64(1),
+		"g_mean":  float64(2),
+		"g_s2":    float64(2),
+		"g_stdev": math.Sqrt(2),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -118,6 +126,10 @@ func TestBasicStatsDifferentPeriods(t *testing.T) {
 		"d_max":   float64(2),
 		"d_min":   float64(2),
 		"d_mean":  float64(2),
+		"g_count": float64(1), //g
+		"g_max":   float64(3),
+		"g_min":   float64(3),
+		"g_mean":  float64(3),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -153,6 +165,10 @@ func TestBasicStatsDifferentPeriods(t *testing.T) {
 		"f_max":   float64(200),
 		"f_min":   float64(200),
 		"f_mean":  float64(200),
+		"g_count": float64(1), //g
+		"g_max":   float64(1),
+		"g_min":   float64(1),
+		"g_mean":  float64(1),
 	}
 	expectedTags = map[string]string{
 		"foo": "bar",
@@ -179,6 +195,7 @@ func TestBasicStatsWithOnlyCount(t *testing.T) {
 		"d_count": float64(2),
 		"e_count": float64(1),
 		"f_count": float64(1),
+		"g_count": float64(2),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -205,6 +222,7 @@ func TestBasicStatsWithOnlyMin(t *testing.T) {
 		"d_min": float64(2),
 		"e_min": float64(200),
 		"f_min": float64(200),
+		"g_min": float64(1),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -231,6 +249,7 @@ func TestBasicStatsWithOnlyMax(t *testing.T) {
 		"d_max": float64(6),
 		"e_max": float64(200),
 		"f_max": float64(200),
+		"g_max": float64(3),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -257,6 +276,7 @@ func TestBasicStatsWithOnlyMean(t *testing.T) {
 		"d_mean": float64(4),
 		"e_mean": float64(200),
 		"f_mean": float64(200),
+		"g_mean": float64(2),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -283,6 +303,7 @@ func TestBasicStatsWithOnlySum(t *testing.T) {
 		"d_sum": float64(8),
 		"e_sum": float64(200),
 		"f_sum": float64(200),
+		"g_sum": float64(4),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -359,6 +380,7 @@ func TestBasicStatsWithOnlyVariance(t *testing.T) {
 		"b_s2": float64(2),
 		"c_s2": float64(2),
 		"d_s2": float64(8),
+		"g_s2": float64(2),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -383,6 +405,7 @@ func TestBasicStatsWithOnlyStandardDeviation(t *testing.T) {
 		"b_stdev": math.Sqrt(2),
 		"c_stdev": math.Sqrt(2),
 		"d_stdev": math.Sqrt(8),
+		"g_stdev": math.Sqrt(2),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -415,6 +438,57 @@ func TestBasicStatsWithMinAndMax(t *testing.T) {
 		"e_min": float64(200),
 		"f_max": float64(200), //f
 		"f_min": float64(200),
+		"g_max": float64(3), //g
+		"g_min": float64(1),
+	}
+	expectedTags := map[string]string{
+		"foo": "bar",
+	}
+	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
+}
+
+// Test only aggregating diff
+func TestBasicStatsWithDiff(t *testing.T) {
+
+	aggregator := NewBasicStats()
+	aggregator.Stats = []string{"diff"}
+
+	aggregator.Add(m1)
+	aggregator.Add(m2)
+
+	acc := testutil.Accumulator{}
+	aggregator.Push(&acc)
+
+	expectedFields := map[string]interface{}{
+		"a_diff": float64(0),
+		"b_diff": float64(2),
+		"c_diff": float64(2),
+		"d_diff": float64(4),
+		"g_diff": float64(-2),
+	}
+	expectedTags := map[string]string{
+		"foo": "bar",
+	}
+	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
+}
+
+// Test only aggregating non_negative_diff
+func TestBasicStatsWithNonNegativeDiff(t *testing.T) {
+
+	aggregator := NewBasicStats()
+	aggregator.Stats = []string{"non_negative_diff"}
+
+	aggregator.Add(m1)
+	aggregator.Add(m2)
+
+	acc := testutil.Accumulator{}
+	aggregator.Push(&acc)
+
+	expectedFields := map[string]interface{}{
+		"a_non_negative_diff": float64(0),
+		"b_non_negative_diff": float64(2),
+		"c_non_negative_diff": float64(2),
+		"d_non_negative_diff": float64(4),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -471,6 +545,13 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"f_min":   float64(200),
 		"f_mean":  float64(200),
 		"f_sum":   float64(200),
+		"g_count": float64(2), //g
+		"g_max":   float64(3),
+		"g_min":   float64(1),
+		"g_mean":  float64(2),
+		"g_s2":    float64(2),
+		"g_stdev": math.Sqrt(2),
+		"g_sum":   float64(4),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",