From 624f27f4b6f10baa88aa7c78a3ddd35fd2cd8717 Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Mon, 16 Mar 2015 15:57:47 +0100
Subject: [PATCH] Add ln, log2, log10 and exp functions to the query language.

---
 rules/ast/functions.go | 68 ++++++++++++++++++++++++++++++
 rules/rules_test.go    | 93 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 160 insertions(+), 1 deletion(-)

diff --git a/rules/ast/functions.go b/rules/ast/functions.go
index 79908cd5b..ea95a1966 100644
--- a/rules/ast/functions.go
+++ b/rules/ast/functions.go
@@ -456,6 +456,50 @@ func ceilImpl(timestamp clientmodel.Timestamp, args []Node) interface{} {
 	return vector
 }
 
+// === exp(vector VectorNode) Vector ===
+func expImpl(timestamp clientmodel.Timestamp, args []Node) interface{} {
+	n := args[0].(VectorNode)
+	vector := n.Eval(timestamp)
+	for _, el := range vector {
+		el.Metric.Delete(clientmodel.MetricNameLabel)
+		el.Value = clientmodel.SampleValue(math.Exp(float64(el.Value)))
+	}
+	return vector
+}
+
+// === ln(vector VectorNode) Vector ===
+func lnImpl(timestamp clientmodel.Timestamp, args []Node) interface{} {
+	n := args[0].(VectorNode)
+	vector := n.Eval(timestamp)
+	for _, el := range vector {
+		el.Metric.Delete(clientmodel.MetricNameLabel)
+		el.Value = clientmodel.SampleValue(math.Log(float64(el.Value)))
+	}
+	return vector
+}
+
+// === log2(vector VectorNode) Vector ===
+func log2Impl(timestamp clientmodel.Timestamp, args []Node) interface{} {
+	n := args[0].(VectorNode)
+	vector := n.Eval(timestamp)
+	for _, el := range vector {
+		el.Metric.Delete(clientmodel.MetricNameLabel)
+		el.Value = clientmodel.SampleValue(math.Log2(float64(el.Value)))
+	}
+	return vector
+}
+
+// === log10(vector VectorNode) Vector ===
+func log10Impl(timestamp clientmodel.Timestamp, args []Node) interface{} {
+	n := args[0].(VectorNode)
+	vector := n.Eval(timestamp)
+	for _, el := range vector {
+		el.Metric.Delete(clientmodel.MetricNameLabel)
+		el.Value = clientmodel.SampleValue(math.Log10(float64(el.Value)))
+	}
+	return vector
+}
+
 // === deriv(node MatrixNode) Vector ===
 func derivImpl(timestamp clientmodel.Timestamp, args []Node) interface{} {
 	matrixNode := args[0].(MatrixNode)
@@ -598,6 +642,12 @@ var functions = map[string]*Function{
 		returnType: VectorType,
 		callFn:     dropCommonLabelsImpl,
 	},
+	"exp": {
+		name:       "exp",
+		argTypes:   []ExprType{VectorType},
+		returnType: VectorType,
+		callFn:     expImpl,
+	},
 	"floor": {
 		name:       "floor",
 		argTypes:   []ExprType{VectorType},
@@ -610,6 +660,24 @@ var functions = map[string]*Function{
 		returnType: VectorType,
 		callFn:     histogramQuantileImpl,
 	},
+	"ln": {
+		name:       "ln",
+		argTypes:   []ExprType{VectorType},
+		returnType: VectorType,
+		callFn:     lnImpl,
+	},
+	"log10": {
+		name:       "log10",
+		argTypes:   []ExprType{VectorType},
+		returnType: VectorType,
+		callFn:     log10Impl,
+	},
+	"log2": {
+		name:       "log2",
+		argTypes:   []ExprType{VectorType},
+		returnType: VectorType,
+		callFn:     log2Impl,
+	},
 	"max_over_time": {
 		name:       "max_over_time",
 		argTypes:   []ExprType{MatrixType},
diff --git a/rules/rules_test.go b/rules/rules_test.go
index baecc50b7..5966c21ec 100644
--- a/rules/rules_test.go
+++ b/rules/rules_test.go
@@ -36,7 +36,7 @@ var (
 	testEvalTime = testStartTime.Add(testSampleInterval * 10)
 	fixturesPath = "fixtures"
 
-	reSample  = regexp.MustCompile(`^(.*)(?: \=\>|:) (\-?\d+\.?\d*e?\d*|[+-]Inf|NaN) \@\[(\d+)\]$`)
+	reSample  = regexp.MustCompile(`^(.*)(?: \=\>|:) (\-?\d+\.?\d*(?:e-?\d*)?|[+-]Inf|NaN) \@\[(\d+)\]$`)
 	minNormal = math.Float64frombits(0x0010000000000000) // The smallest positive normal value of type float64.
 )
 
@@ -1197,6 +1197,97 @@ func TestExpressions(t *testing.T) {
 				`{group="canary", instance="0", job="api-server"} => NaN @[%v]`,
 			},
 		},
+		{
+			expr: `exp(vector_matching_a)`,
+			output: []string{
+				`{l="x"} => 22026.465794806718 @[%v]`,
+				`{l="y"} => 485165195.4097903 @[%v]`,
+			},
+		},
+		{
+			expr: `exp(vector_matching_a - 10)`,
+			output: []string{
+				`{l="y"} => 22026.465794806718 @[%v]`,
+				`{l="x"} => 1 @[%v]`,
+			},
+		},
+		{
+			expr: `exp(vector_matching_a - 20)`,
+			output: []string{
+				`{l="x"} => 4.5399929762484854e-05 @[%v]`,
+				`{l="y"} => 1 @[%v]`,
+			},
+		},
+		{
+			expr: `ln(vector_matching_a)`,
+			output: []string{
+				`{l="x"} => 2.302585092994046 @[%v]`,
+				`{l="y"} => 2.995732273553991 @[%v]`,
+			},
+		},
+		{
+			expr: `ln(vector_matching_a - 10)`,
+			output: []string{
+				`{l="y"} => 2.302585092994046 @[%v]`,
+				`{l="x"} => -Inf @[%v]`,
+			},
+		},
+		{
+			expr: `ln(vector_matching_a - 20)`,
+			output: []string{
+				`{l="y"} => -Inf @[%v]`,
+				`{l="x"} => NaN @[%v]`,
+			},
+		},
+		{
+			expr: `exp(ln(vector_matching_a))`,
+			output: []string{
+				`{l="y"} => 20 @[%v]`,
+				`{l="x"} => 10 @[%v]`,
+			},
+		},
+		{
+			expr: `log2(vector_matching_a)`,
+			output: []string{
+				`{l="x"} => 3.3219280948873626 @[%v]`,
+				`{l="y"} => 4.321928094887363 @[%v]`,
+			},
+		},
+		{
+			expr: `log2(vector_matching_a - 10)`,
+			output: []string{
+				`{l="y"} => 3.3219280948873626 @[%v]`,
+				`{l="x"} => -Inf @[%v]`,
+			},
+		},
+		{
+			expr: `log2(vector_matching_a - 20)`,
+			output: []string{
+				`{l="x"} => NaN @[%v]`,
+				`{l="y"} => -Inf @[%v]`,
+			},
+		},
+		{
+			expr: `log10(vector_matching_a)`,
+			output: []string{
+				`{l="x"} => 1 @[%v]`,
+				`{l="y"} => 1.301029995663981 @[%v]`,
+			},
+		},
+		{
+			expr: `log10(vector_matching_a - 10)`,
+			output: []string{
+				`{l="y"} => 1 @[%v]`,
+				`{l="x"} => -Inf @[%v]`,
+			},
+		},
+		{
+			expr: `log10(vector_matching_a - 20)`,
+			output: []string{
+				`{l="x"} => NaN @[%v]`,
+				`{l="y"} => -Inf @[%v]`,
+			},
+		},
 	}
 
 	storage, closer := newTestStorage(t)