Changing StatsD in telegraf so that it able to fetch timestamp from metric tags instead of using current timestamp

plugins/inputs/statsd/statsd.go

@@ -61,6 +61,7 @@ type Statsd struct {
 
 	// bucket -> influx templates
 	Templates []string
+        timestamp time.Time 
 }
 
 func NewStatsd() *Statsd {
@@ -92,30 +93,35 @@ type metric struct {
 	additive   bool
 	samplerate float64
 	tags       map[string]string
+        timestamp  time.Time 
 }
 
 type cachedset struct {
 	name   string
 	fields map[string]map[int64]bool
 	tags   map[string]string
+        timestamp time.Time 
 }
 
 type cachedgauge struct {
 	name   string
 	fields map[string]interface{}
 	tags   map[string]string
+        timestamp time.Time 
 }
 
 type cachedcounter struct {
 	name   string
 	fields map[string]interface{}
 	tags   map[string]string
+        timestamp time.Time 
 }
 
 type cachedtimings struct {
 	name  string
 	stats RunningStats
 	tags  map[string]string
+        timestamp time.Time 
 }
 
 func (_ *Statsd) Description() string {
@@ -166,8 +172,6 @@ func (_ *Statsd) SampleConfig() string {
 func (s *Statsd) Gather(acc telegraf.Accumulator) error {
 	s.Lock()
 	defer s.Unlock()
-	now := time.Now()
-
 	for _, metric := range s.timings {
 		fields := make(map[string]interface{})
 		fields["mean"] = metric.stats.Mean()
@@ -179,21 +183,21 @@ func (s *Statsd) Gather(acc telegraf.Accumulator) error {
 			name := fmt.Sprintf("%v_percentile", percentile)
 			fields[name] = metric.stats.Percentile(percentile)
 		}
-		acc.AddFields(metric.name, fields, metric.tags, now)
+		acc.AddFields(metric.name, fields, metric.tags, metric.timestamp)
 	}
 	if s.DeleteTimings {
 		s.timings = make(map[string]cachedtimings)
 	}
 
 	for _, metric := range s.gauges {
-		acc.AddFields(metric.name, metric.fields, metric.tags, now)
+		acc.AddFields(metric.name, metric.fields, metric.tags, metric.timestamp)
 	}
 	if s.DeleteGauges {
 		s.gauges = make(map[string]cachedgauge)
 	}
 
 	for _, metric := range s.counters {
-		acc.AddFields(metric.name, metric.fields, metric.tags, now)
+		acc.AddFields(metric.name, metric.fields, metric.tags, metric.timestamp)
 	}
 	if s.DeleteCounters {
 		s.counters = make(map[string]cachedcounter)
@@ -204,7 +208,7 @@ func (s *Statsd) Gather(acc telegraf.Accumulator) error {
 		for field, set := range metric.fields {
 			fields[field] = int64(len(set))
 		}
-		acc.AddFields(metric.name, fields, metric.tags, now)
+		acc.AddFields(metric.name, fields, metric.tags, metric.timestamp)
 	}
 	if s.DeleteSets {
 		s.sets = make(map[string]cachedset)
@@ -390,8 +394,20 @@ func (s *Statsd) parseStatsdLine(line string) error {
 
 		// Make a unique key for the measurement name/tags
 		var tg []string
+                timestamp_available := false
 		for k, v := range m.tags {
 			tg = append(tg, fmt.Sprintf("%s=%s", k, v))
+                        if (k == "timestamp") {
+                                i, err := strconv.ParseInt(v, 10, 64)
+                                if err != nil {
+                                        panic(err)
+                                }
+                                m.timestamp = time.Unix(i, 0)
+                                timestamp_available = true
+                        }
+		}
+                if (!timestamp_available) {
+                        m.timestamp = time.Now()
                 }
 		sort.Strings(tg)
 		m.hash = fmt.Sprintf("%s%s", strings.Join(tg, ""), m.name)
@@ -466,6 +482,7 @@ func (s *Statsd) aggregate(m metric) {
 			cached = cachedtimings{
 				name: m.name,
 				tags: m.tags,
+                                timestamp: m.timestamp,
 				stats: RunningStats{
 					PercLimit: s.PercentileLimit,
 				},
@@ -489,6 +506,7 @@ func (s *Statsd) aggregate(m metric) {
 				name:   m.name,
 				fields: make(map[string]interface{}),
 				tags:   m.tags,
+                                timestamp: m.timestamp,
 			}
 		}
 		// check if the field exists
@@ -506,6 +524,7 @@ func (s *Statsd) aggregate(m metric) {
 				name:   m.name,
 				fields: make(map[string]interface{}),
 				tags:   m.tags,
+                                timestamp: m.timestamp,
 			}
 		}
 		// check if the field exists
@@ -527,6 +546,7 @@ func (s *Statsd) aggregate(m metric) {
 				name:   m.name,
 				fields: make(map[string]map[int64]bool),
 				tags:   m.tags,
+                                timestamp: m.timestamp,
 			}
 		}
 		// check if the field exists