Fix: 0 samples/sec in throughput by logging metric metadata throughput.

Signed-off-by: Harkishen-Singh <[email protected]>

This commit fixes `0 samples/sec` logging in throughput. The reason
behind this behaviour was metric-metadata not being printed, rather
it was just updating the `metrics-max-ts-send`, which was causing the log.

The `metrics-max-ts-send` was updated even when we were writing metadata.

This commit also updates the logging of throughput, by making samples, spans
and metric-metadata log in the same line, than the earlier separate lines. This
allows better utilization of log lines.

Author: Harkishen-Singh

CHANGELOG.md

@@ -18,7 +18,10 @@ We use the following categories for changes:
   reader and writer [#1020].
 - Run timescaledb-tune with the promscale profile [#1615]
 - Propagate the context from received HTTP read requests downstream to database
-  requests [#1205]. 
+  requests [#1205]
+
+### Changed
+- Log throughput in the same line for samples, spans and metric metadata [#1643]
 
 ### Fixed
 - Fix broken cache eviction in clockcache [#1603]

pkg/util/throughput/throughput.go

@@ -5,6 +5,7 @@
 package throughput
 
 import (
+	"fmt"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -70,16 +71,24 @@ func (tc *throughputCalc) run() {
 			continue
 		}
 
-		if samplesRate+metadataRate != 0 {
-			// Metric data ingested.
+		throughput := []interface{}{"msg", "ingestor throughput"}
+		if samplesRate != 0 {
 			maxSentTs := timestamp.Time(atomic.LoadInt64(&tc.metricsMaxSentTs))
-			log.Info("msg", "ingestor throughput", "samples/sec", int(samplesRate), "metrics-max-sent-ts", maxSentTs)
+			throughput = append(throughput, []interface{}{"samples/sec", fmt.Sprint(int(samplesRate)), "metrics-max-sent-ts", maxSentTs.String()}...)
 		}
 
 		if spansRate != 0 {
-			// Spans ingested.
 			spansLastWriteOn := timestamp.Time(atomic.LoadInt64(&tc.spansLastWriteOn))
-			log.Info("msg", "ingestor throughput", "spans/sec", int(spansRate), "spans-last-write-on", spansLastWriteOn)
+			throughput = append(throughput, []interface{}{"spans/sec", fmt.Sprint(int(spansRate)), "spans-last-write-on", spansLastWriteOn.String()}...)
+		}
+
+		if metadataRate != 0 {
+			throughput = append(throughput, []interface{}{"metric-metadata/sec", fmt.Sprint(metadataRate)}...)
+		}
+
+		if len(throughput) > 2 {
+			// Log only if we had any activity.
+			log.Info(throughput...)
 		}
 	}
 }