From f90c7a11d16da9244d6acd971513f409211a5748 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Thu, 29 Aug 2024 11:57:31 +0100
Subject: [PATCH] [REFACTOR] OTLP translator: simplify time conversion

We don't need multiple levels of abstraction to convert nanoseconds to
milliseconds.
We do benefit from tests, however.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
---
 .../prometheusremotewrite/helper.go           |  3 +--
 .../prometheusremotewrite/helper_test.go      | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/storage/remote/otlptranslator/prometheusremotewrite/helper.go b/storage/remote/otlptranslator/prometheusremotewrite/helper.go
index f2d7ecd4e..67cf28119 100644
--- a/storage/remote/otlptranslator/prometheusremotewrite/helper.go
+++ b/storage/remote/otlptranslator/prometheusremotewrite/helper.go
@@ -24,7 +24,6 @@ import (
 	"slices"
 	"sort"
 	"strconv"
-	"time"
 	"unicode/utf8"
 
 	"github.com/cespare/xxhash/v2"
@@ -594,5 +593,5 @@ func addResourceTargetInfo(resource pcommon.Resource, settings Settings, timesta
 
 // convertTimeStamp converts OTLP timestamp in ns to timestamp in ms
 func convertTimeStamp(timestamp pcommon.Timestamp) int64 {
-	return timestamp.AsTime().UnixNano() / (int64(time.Millisecond) / int64(time.Nanosecond))
+	return int64(timestamp) / 1_000_000
 }
diff --git a/storage/remote/otlptranslator/prometheusremotewrite/helper_test.go b/storage/remote/otlptranslator/prometheusremotewrite/helper_test.go
index c4dd781ae..729d99b8a 100644
--- a/storage/remote/otlptranslator/prometheusremotewrite/helper_test.go
+++ b/storage/remote/otlptranslator/prometheusremotewrite/helper_test.go
@@ -14,6 +14,7 @@ package prometheusremotewrite
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"go.opentelemetry.io/collector/pdata/pcommon"
@@ -159,3 +160,21 @@ func TestCreateAttributes(t *testing.T) {
 		})
 	}
 }
+
+func Test_convertTimeStamp(t *testing.T) {
+	tests := []struct {
+		name string
+		arg  pcommon.Timestamp
+		want int64
+	}{
+		{"zero", 0, 0},
+		{"1ms", 1_000_000, 1},
+		{"1s", pcommon.Timestamp(time.Unix(1, 0).UnixNano()), 1000},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := convertTimeStamp(tt.arg)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}