From 9461d3fdfaf9a41194f6ba479f5c717d6581ee79 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Sat, 13 May 2023 20:12:06 -0700
Subject: [PATCH] lib/promutils: add ParseTimeAt() function

---
 lib/promutils/time.go      | 15 ++++++--
 lib/promutils/time_test.go | 75 +++++++++++++++++++-------------------
 2 files changed, 49 insertions(+), 41 deletions(-)

diff --git a/lib/promutils/time.go b/lib/promutils/time.go
index 432c2dbc0..986790f43 100644
--- a/lib/promutils/time.go
+++ b/lib/promutils/time.go
@@ -13,8 +13,18 @@ import (
 //
 // It returns unix timestamp in seconds.
 func ParseTime(s string) (float64, error) {
+	currentTimestamp := float64(time.Now().UnixNano()) / 1e9
+	return ParseTimeAt(s, currentTimestamp)
+}
+
+// ParseTimeAt parses time s in different formats, assuming the given currentTimestamp.
+//
+// See https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#timestamp-formats
+//
+// It returns unix timestamp in seconds.
+func ParseTimeAt(s string, currentTimestamp float64) (float64, error) {
 	if s == "now" {
-		return float64(time.Now().UnixNano()) / 1e9, nil
+		return currentTimestamp, nil
 	}
 	sOrig := s
 	tzOffset := float64(0)
@@ -49,8 +59,7 @@ func ParseTime(s string) (float64, error) {
 		if d > 0 {
 			d = -d
 		}
-		t := time.Now().Add(d)
-		return float64(t.UnixNano()) / 1e9, nil
+		return currentTimestamp + float64(d)/1e9, nil
 	}
 	if len(s) == 4 {
 		// Parse YYYY
diff --git a/lib/promutils/time_test.go b/lib/promutils/time_test.go
index 740805227..fec51f6ac 100644
--- a/lib/promutils/time_test.go
+++ b/lib/promutils/time_test.go
@@ -1,19 +1,18 @@
 package promutils
 
 import (
-	"math"
 	"testing"
 	"time"
 )
 
-func TestParseTimeSuccess(t *testing.T) {
-	f := func(s string, resultExpected float64) {
+func TestParseTimeAtSuccess(t *testing.T) {
+	f := func(s string, currentTime, resultExpected float64) {
 		t.Helper()
-		result, err := ParseTime(s)
+		result, err := ParseTimeAt(s, currentTime)
 		if err != nil {
 			t.Fatalf("unexpected error: %s", err)
 		}
-		if math.Abs(result-resultExpected) > 10 {
+		if result != resultExpected {
 			t.Fatalf("unexpected result; got %v; want %v", result, resultExpected)
 		}
 	}
@@ -21,55 +20,55 @@ func TestParseTimeSuccess(t *testing.T) {
 	now := float64(time.Now().UnixNano()) / 1e9
 
 	// duration relative to the current time
-	f("now", now)
-	f("1h5s", now-3605)
+	f("now", now, now)
+	f("1h5s", now, now-3605)
 
 	// negative duration relative to the current time
-	f("-5m", now-5*60)
-	f("-123", now-123)
-	f("-123.456", now-123.456)
-	f("now-1h5m", now-(3600+5*60))
+	f("-5m", now, now-5*60)
+	f("-123", now, now-123)
+	f("-123.456", now, now-123.456)
+	f("now-1h5m", now, now-(3600+5*60))
 
 	// Year
-	f("2023", 1.6725312e+09)
-	f("2023Z", 1.6725312e+09)
-	f("2023+02:00", 1.672524e+09)
-	f("2023-02:00", 1.6725384e+09)
+	f("2023", now, 1.6725312e+09)
+	f("2023Z", now, 1.6725312e+09)
+	f("2023+02:00", now, 1.672524e+09)
+	f("2023-02:00", now, 1.6725384e+09)
 
 	// Year and month
-	f("2023-05", 1.6828992e+09)
-	f("2023-05Z", 1.6828992e+09)
-	f("2023-05+02:00", 1.682892e+09)
-	f("2023-05-02:00", 1.6829064e+09)
+	f("2023-05", now, 1.6828992e+09)
+	f("2023-05Z", now, 1.6828992e+09)
+	f("2023-05+02:00", now, 1.682892e+09)
+	f("2023-05-02:00", now, 1.6829064e+09)
 
 	// Year, month and day
-	f("2023-05-20", 1.6845408e+09)
-	f("2023-05-20Z", 1.6845408e+09)
-	f("2023-05-20+02:30", 1.6845318e+09)
-	f("2023-05-20-02:30", 1.6845498e+09)
+	f("2023-05-20", now, 1.6845408e+09)
+	f("2023-05-20Z", now, 1.6845408e+09)
+	f("2023-05-20+02:30", now, 1.6845318e+09)
+	f("2023-05-20-02:30", now, 1.6845498e+09)
 
 	// Year, month, day and hour
-	f("2023-05-20T04", 1.6845552e+09)
-	f("2023-05-20T04Z", 1.6845552e+09)
-	f("2023-05-20T04+02:30", 1.6845462e+09)
-	f("2023-05-20T04-02:30", 1.6845642e+09)
+	f("2023-05-20T04", now, 1.6845552e+09)
+	f("2023-05-20T04Z", now, 1.6845552e+09)
+	f("2023-05-20T04+02:30", now, 1.6845462e+09)
+	f("2023-05-20T04-02:30", now, 1.6845642e+09)
 
 	// Year, month, day, hour and minute
-	f("2023-05-20T04:57", 1.68455862e+09)
-	f("2023-05-20T04:57Z", 1.68455862e+09)
-	f("2023-05-20T04:57+02:30", 1.68454962e+09)
-	f("2023-05-20T04:57-02:30", 1.68456762e+09)
+	f("2023-05-20T04:57", now, 1.68455862e+09)
+	f("2023-05-20T04:57Z", now, 1.68455862e+09)
+	f("2023-05-20T04:57+02:30", now, 1.68454962e+09)
+	f("2023-05-20T04:57-02:30", now, 1.68456762e+09)
 
 	// Year, month, day, hour, minute and second
-	f("2023-05-20T04:57:43", 1.684558663e+09)
-	f("2023-05-20T04:57:43Z", 1.684558663e+09)
-	f("2023-05-20T04:57:43+02:30", 1.684549663e+09)
-	f("2023-05-20T04:57:43-02:30", 1.684567663e+09)
+	f("2023-05-20T04:57:43", now, 1.684558663e+09)
+	f("2023-05-20T04:57:43Z", now, 1.684558663e+09)
+	f("2023-05-20T04:57:43+02:30", now, 1.684549663e+09)
+	f("2023-05-20T04:57:43-02:30", now, 1.684567663e+09)
 
 	// milliseconds
-	f("2023-05-20T04:57:43.123Z", 1.6845586631230001e+09)
-	f("2023-05-20T04:57:43.123456789+02:30", 1.6845496631234567e+09)
-	f("2023-05-20T04:57:43.123456789-02:30", 1.6845676631234567e+09)
+	f("2023-05-20T04:57:43.123Z", now, 1.6845586631230001e+09)
+	f("2023-05-20T04:57:43.123456789+02:30", now, 1.6845496631234567e+09)
+	f("2023-05-20T04:57:43.123456789-02:30", now, 1.6845676631234567e+09)
 }
 
 func TestParseTimeFailure(t *testing.T) {