From 375fc86af7595e2ec83d46d5482172c1bb69abf0 Mon Sep 17 00:00:00 2001
From: Cyril Tovena <cyril.tovena@gmail.com>
Date: Wed, 5 Feb 2020 09:55:00 -0500
Subject: [PATCH] Fixes stats summary computation. (#1636)

* Fixes stats summary computation.

Signed-off-by: Cyril Tovena <cyril.tovena@gmail.com>

* Fixes division by zero

Signed-off-by: Cyril Tovena <cyril.tovena@gmail.com>
---
 pkg/logql/stats/context.go      | 40 ++++++++++++++++-----------------
 pkg/logql/stats/context_test.go | 39 ++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 20 deletions(-)

diff --git a/pkg/logql/stats/context.go b/pkg/logql/stats/context.go
index de5aaf6bbe209..9371297ac5121 100644
--- a/pkg/logql/stats/context.go
+++ b/pkg/logql/stats/context.go
@@ -153,31 +153,29 @@ func Snapshot(ctx context.Context, execTime time.Duration) Result {
 		res.Store.CompressedBytes = c.CompressedBytes
 		res.Store.TotalDuplicates = c.TotalDuplicates
 	}
+	res.ComputeSummary(execTime)
+	return res
+}
 
+// ComputeSummary calculates the summary based on store and ingester data.
+func (r *Result) ComputeSummary(execTime time.Duration) {
 	// calculate the summary
-	res.Summary.TotalBytesProcessed = res.Store.DecompressedBytes + res.Store.HeadChunkBytes +
-		res.Ingester.DecompressedBytes + res.Ingester.HeadChunkBytes
-	res.Summary.BytesProcessedPerSeconds =
-		int64(float64(res.Summary.TotalBytesProcessed) /
-			execTime.Seconds())
-	res.Summary.TotalLinesProcessed = res.Store.DecompressedLines + res.Store.HeadChunkLines +
-		res.Ingester.DecompressedLines + res.Ingester.HeadChunkLines
-	res.Summary.LinesProcessedPerSeconds =
-		int64(float64(res.Summary.TotalLinesProcessed) /
-			execTime.Seconds())
-	res.Summary.ExecTime = execTime.Seconds()
-	return res
+	r.Summary.TotalBytesProcessed = r.Store.DecompressedBytes + r.Store.HeadChunkBytes +
+		r.Ingester.DecompressedBytes + r.Ingester.HeadChunkBytes
+	r.Summary.TotalLinesProcessed = r.Store.DecompressedLines + r.Store.HeadChunkLines +
+		r.Ingester.DecompressedLines + r.Ingester.HeadChunkLines
+	r.Summary.ExecTime = execTime.Seconds()
+	if execTime != 0 {
+		r.Summary.BytesProcessedPerSeconds =
+			int64(float64(r.Summary.TotalBytesProcessed) /
+				execTime.Seconds())
+		r.Summary.LinesProcessedPerSeconds =
+			int64(float64(r.Summary.TotalLinesProcessed) /
+				execTime.Seconds())
+	}
 }
 
 func (r *Result) Merge(m Result) {
-	if r == nil {
-		return
-	}
-	r.Summary.BytesProcessedPerSeconds += m.Summary.BytesProcessedPerSeconds
-	r.Summary.LinesProcessedPerSeconds += m.Summary.LinesProcessedPerSeconds
-	r.Summary.TotalBytesProcessed += m.Summary.TotalBytesProcessed
-	r.Summary.TotalLinesProcessed += m.Summary.TotalLinesProcessed
-	r.Summary.ExecTime += m.Summary.ExecTime
 
 	r.Store.TotalChunksRef += m.Store.TotalChunksRef
 	r.Store.TotalChunksDownloaded += m.Store.TotalChunksDownloaded
@@ -199,4 +197,6 @@ func (r *Result) Merge(m Result) {
 	r.Ingester.DecompressedLines += m.Ingester.DecompressedLines
 	r.Ingester.CompressedBytes += m.Ingester.CompressedBytes
 	r.Ingester.TotalDuplicates += m.Ingester.TotalDuplicates
+
+	r.ComputeSummary(time.Duration(int64((r.Summary.ExecTime + m.Summary.ExecTime) * float64(time.Second))))
 }
diff --git a/pkg/logql/stats/context_test.go b/pkg/logql/stats/context_test.go
index 5873b3d77b204..b160544261f96 100644
--- a/pkg/logql/stats/context_test.go
+++ b/pkg/logql/stats/context_test.go
@@ -88,6 +88,9 @@ func fakeIngesterQuery(ctx context.Context) {
 func TestResult_Merge(t *testing.T) {
 	var res Result
 
+	res.Merge(res) // testing zero.
+	require.Equal(t, res, res)
+
 	toMerge := Result{
 		Ingester: Ingester{
 			TotalChunksMatched: 200,
@@ -123,4 +126,40 @@ func TestResult_Merge(t *testing.T) {
 
 	res.Merge(toMerge)
 	require.Equal(t, toMerge, res)
+
+	// merge again
+	res.Merge(toMerge)
+	require.Equal(t, Result{
+		Ingester: Ingester{
+			TotalChunksMatched: 2 * 200,
+			TotalBatches:       2 * 50,
+			TotalLinesSent:     2 * 60,
+			HeadChunkBytes:     2 * 10,
+			HeadChunkLines:     2 * 20,
+			DecompressedBytes:  2 * 24,
+			DecompressedLines:  2 * 40,
+			CompressedBytes:    2 * 60,
+			TotalDuplicates:    2 * 2,
+			TotalReached:       2 * 2,
+		},
+		Store: Store{
+			TotalChunksRef:        2 * 50,
+			TotalChunksDownloaded: 2 * 60,
+			ChunksDownloadTime:    2 * time.Second.Seconds(),
+			HeadChunkBytes:        2 * 10,
+			HeadChunkLines:        2 * 20,
+			DecompressedBytes:     2 * 40,
+			DecompressedLines:     2 * 20,
+			CompressedBytes:       2 * 30,
+			TotalDuplicates:       2 * 10,
+		},
+		Summary: Summary{
+			ExecTime:                 2 * 2 * time.Second.Seconds(),
+			BytesProcessedPerSeconds: int64(42), // 2 requests at the same pace should give the same bytes/lines per sec
+			LinesProcessedPerSeconds: int64(50),
+			TotalBytesProcessed:      2 * int64(84),
+			TotalLinesProcessed:      2 * int64(100),
+		},
+	}, res)
+
 }