From 4e3abc6cbf7f1d25499f9be0a9838683b0754468 Mon Sep 17 00:00:00 2001
From: beorn7 <beorn@soundcloud.com>
Date: Tue, 8 Nov 2016 21:03:31 +0100
Subject: [PATCH] Simply use `math.Mod(float64, float64)` after all

This circumvents all the problems with int overflow, plus it is what was originally intended.
---
 promql/engine.go               | 10 ++--------
 promql/testdata/operators.test | 19 ++++---------------
 2 files changed, 6 insertions(+), 23 deletions(-)

diff --git a/promql/engine.go b/promql/engine.go
index 82548e0c4..253dc4245 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -1037,10 +1037,7 @@ func scalarBinop(op itemType, lhs, rhs model.SampleValue) model.SampleValue {
 	case itemPOW:
 		return model.SampleValue(math.Pow(float64(lhs), float64(rhs)))
 	case itemMOD:
-		if int64(rhs) != 0 && convertibleToInt64(lhs) && convertibleToInt64(rhs) {
-			return model.SampleValue(int64(lhs) % int64(rhs))
-		}
-		return model.SampleValue(math.NaN())
+		return model.SampleValue(math.Mod(float64(lhs), float64(rhs)))
 	case itemEQL:
 		return btos(lhs == rhs)
 	case itemNEQ:
@@ -1071,10 +1068,7 @@ func vectorElemBinop(op itemType, lhs, rhs model.SampleValue) (model.SampleValue
 	case itemPOW:
 		return model.SampleValue(math.Pow(float64(lhs), float64(rhs))), true
 	case itemMOD:
-		if int64(rhs) != 0 && convertibleToInt64(lhs) && convertibleToInt64(rhs) {
-			return model.SampleValue(int64(lhs) % int64(rhs)), true
-		}
-		return model.SampleValue(math.NaN()), true
+		return model.SampleValue(math.Mod(float64(lhs), float64(rhs))), true
 	case itemEQL:
 		return lhs, lhs == rhs
 	case itemNEQ:
diff --git a/promql/testdata/operators.test b/promql/testdata/operators.test
index c14386aa9..2807991f3 100644
--- a/promql/testdata/operators.test
+++ b/promql/testdata/operators.test
@@ -35,8 +35,8 @@ eval instant at 50m SUM(http_requests) BY (job) % 3
 	{job="app-server"} 2
 
 eval instant at 50m SUM(http_requests) BY (job) % 0.3
-	{job="api-server"} NaN
-	{job="app-server"} NaN
+	{job="api-server"} 0.1
+	{job="app-server"} 0.2
 
 eval instant at 50m SUM(http_requests) BY (job) ^ 2
 	{job="api-server"} 1000000
@@ -54,10 +54,9 @@ eval instant at 50m SUM(http_requests) BY (job) % 2 ^ 3 ^ 2
 	{job="api-server"} 488
 	{job="app-server"} 40
 
-# int64 overflow on RHS of %.
 eval instant at 50m SUM(http_requests) BY (job) % 2 ^ 3 ^ 2 ^ 2
-	{job="api-server"} NaN
-	{job="app-server"} NaN
+	{job="api-server"} 1000
+	{job="app-server"} 2600
 
 eval instant at 50m COUNT(http_requests) BY (job) ^ COUNT(http_requests) BY (job)
 	{job="api-server"} 256
@@ -352,13 +351,3 @@ eval instant at 5m metricA + ignoring() metricB
 
 eval instant at 5m metricA + metricB
   {baz="meh"} 7
-
-clear
-
-load 5m
-  finite{foo="bar"} 42
-  almost_zero{foo="bar"} 0.123
-
-# MOD by "almost zero" with vector.
-eval instant at 5m finite % almost_zero
-  {foo="bar"} NaN
\ No newline at end of file