From efd4e05fcadc1e7c83b8a6f80ea37736e4817410 Mon Sep 17 00:00:00 2001
From: Aryansharma9917 <sharmaaryan9837@gmail.com>
Date: Sun, 14 May 2023 18:04:22 +0530
Subject: [PATCH] #138 : Added absent_over_time support function

---
 engine/engine_test.go           | 10 ++++++++++
 execution/function/functions.go |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/engine/engine_test.go b/engine/engine_test.go
index 57315d02..735cb8d3 100644
--- a/engine/engine_test.go
+++ b/engine/engine_test.go
@@ -184,6 +184,16 @@ func TestQueriesAgainstOldEngine(t *testing.T) {
 					http_requests_total{pod="nginx-2"} -5+2x18`,
 			query: "abs(http_requests_total)",
 		},
+		{
+			name: "absent_over_time",
+			load: `load 30s
+					http_requests_total{pod="nginx-1"} 1+1x15
+					http_requests_total{pod="nginx-2"} 1+2x18
+					http_requests_total{pod="nginx-2"} 1+2x18
+					http_requests_total{pod="nginx-2"} 1+2x18
+					http_requests_total{pod="nginx-2"} 1+2x18`,
+			query: "absent_over_time(http_requests_total[30s])",
+		},
 		{
 			name: "ceil",
 			load: `load 30s
diff --git a/execution/function/functions.go b/execution/function/functions.go
index e59aab56..302536fc 100644
--- a/execution/function/functions.go
+++ b/execution/function/functions.go
@@ -87,6 +87,13 @@ var Funcs = map[string]FunctionCall{
 	"deg": simpleFunc(func(v float64) float64 {
 		return v * 180 / math.Pi
 	}),
+	"absent_over_time": simpleFunc(func(v float64) float64 {
+		if v > 0 {
+			return 0
+		} else {
+			return 1
+		}
+	}),
 	"sgn": simpleFunc(func(v float64) float64 {
 		var sign float64
 		if v > 0 {