Add sort() and sort_desc() expression language functions.

rules/ast/functions.go

@@ -17,6 +17,8 @@ import (
 	"errors"
 	"fmt"
 	"github.com/prometheus/prometheus/model"
+	"github.com/prometheus/prometheus/utility"
+	"sort"
 	"time"
 )
 
@@ -62,17 +64,17 @@ func (function *Function) CheckArgTypes(args []Node) error {
 	return nil
 }
 
-// === time() ===
+// === time() model.SampleValue ===
 func timeImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	return model.SampleValue(time.Now().Unix())
 }
 
-// === count(vector VectorNode) ===
+// === count(vector VectorNode) model.SampleValue ===
 func countImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	return model.SampleValue(len(args[0].(VectorNode).Eval(timestamp, view)))
 }
 
-// === delta(matrix MatrixNode, isCounter ScalarNode) ===
+// === delta(matrix MatrixNode, isCounter ScalarNode) Vector ===
 func deltaImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	matrixNode := args[0].(MatrixNode)
 	isCounter := int(args[1].(ScalarNode).Eval(timestamp, view))
@@ -108,7 +110,7 @@ func deltaImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{}
 	return resultVector
 }
 
-// === rate(node *MatrixNode) ===
+// === rate(node *MatrixNode) Vector ===
 func rateImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	args = append(args, &ScalarLiteral{value: 1})
 	vector := deltaImpl(timestamp, view, args).(Vector)
@@ -123,7 +125,43 @@ func rateImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	return vector
 }
 
-// === sampleVectorImpl() ===
+type vectorByValueSorter struct {
+	vector Vector
+}
+
+func (sorter vectorByValueSorter) Len() int {
+	return len(sorter.vector)
+}
+
+func (sorter vectorByValueSorter) Less(i, j int) (less bool) {
+	return sorter.vector[i].Value < sorter.vector[j].Value
+}
+
+func (sorter vectorByValueSorter) Swap(i, j int) {
+	sorter.vector[i], sorter.vector[j] = sorter.vector[j], sorter.vector[i]
+}
+
+// === sort(node *VectorNode) Vector ===
+func sortImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
+	byValueSorter := vectorByValueSorter{
+		vector: args[0].(VectorNode).Eval(timestamp, view),
+	}
+	sort.Sort(byValueSorter)
+	return byValueSorter.vector
+}
+
+// === sortDesc(node *VectorNode) Vector ===
+func sortDescImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
+	descByValueSorter := utility.ReverseSorter{
+		vectorByValueSorter{
+			vector: args[0].(VectorNode).Eval(timestamp, view),
+		},
+	}
+	sort.Sort(descByValueSorter)
+	return descByValueSorter.Interface.(vectorByValueSorter).vector
+}
+
+// === sampleVectorImpl() Vector ===
 func sampleVectorImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
 	return Vector{
 		model.Sample{
@@ -197,12 +235,6 @@ func sampleVectorImpl(timestamp time.Time, view *viewAdapter, args []Node) inter
 }
 
 var functions = map[string]*Function{
-	"time": {
-		name:       "time",
-		argTypes:   []ExprType{},
-		returnType: SCALAR,
-		callFn:     timeImpl,
-	},
 	"count": {
 		name:       "count",
 		argTypes:   []ExprType{VECTOR},
@@ -227,6 +259,24 @@ var functions = map[string]*Function{
 		returnType: VECTOR,
 		callFn:     sampleVectorImpl,
 	},
+	"sort": {
+		name:       "sort",
+		argTypes:   []ExprType{VECTOR},
+		returnType: VECTOR,
+		callFn:     sortImpl,
+	},
+	"sort_desc": {
+		name:       "sort_desc",
+		argTypes:   []ExprType{VECTOR},
+		returnType: VECTOR,
+		callFn:     sortDescImpl,
+	},
+	"time": {
+		name:       "time",
+		argTypes:   []ExprType{},
+		returnType: SCALAR,
+		callFn:     timeImpl,
+	},
 }
 
 func GetFunction(name string) (*Function, error) {

rules/ast/printer.go

@@ -88,7 +88,6 @@ func (vector Vector) String() string {
 				strings.Join(labelStrings, ","),
 				sample.Value, sample.Timestamp))
 	}
-	sort.Strings(metricStrings)
 	return strings.Join(metricStrings, "\n")
 }
 

rules/rules_test.go

@@ -25,12 +25,12 @@ import (
 
 var testEvalTime = testStartTime.Add(testDuration5m * 10)
 
-// Expected output needs to be alphabetically sorted (labels within one line
-// must be sorted and lines between each other must be sorted too).
+// Labels in expected output need to be alphabetically sorted.
 var expressionTests = []struct {
 	expr           string
 	output         []string
 	shouldFail     bool
+	checkOrder     bool
 	fullRanges     int
 	intervalRanges int
 }{
@@ -179,6 +179,36 @@ var expressionTests = []struct {
 		},
 		fullRanges:     8,
 		intervalRanges: 0,
+	}, {
+		expr: "sort(http_requests)",
+		output: []string{
+			"http_requests{group='production',instance='0',job='api-server'} => 100 @[%v]",
+			"http_requests{group='production',instance='1',job='api-server'} => 200 @[%v]",
+			"http_requests{group='canary',instance='0',job='api-server'} => 300 @[%v]",
+			"http_requests{group='canary',instance='1',job='api-server'} => 400 @[%v]",
+			"http_requests{group='production',instance='0',job='app-server'} => 500 @[%v]",
+			"http_requests{group='production',instance='1',job='app-server'} => 600 @[%v]",
+			"http_requests{group='canary',instance='0',job='app-server'} => 700 @[%v]",
+			"http_requests{group='canary',instance='1',job='app-server'} => 800 @[%v]",
+		},
+		checkOrder:     true,
+		fullRanges:     0,
+		intervalRanges: 8,
+	}, {
+		expr: "sort_desc(http_requests)",
+		output: []string{
+			"http_requests{group='canary',instance='1',job='app-server'} => 800 @[%v]",
+			"http_requests{group='canary',instance='0',job='app-server'} => 700 @[%v]",
+			"http_requests{group='production',instance='1',job='app-server'} => 600 @[%v]",
+			"http_requests{group='production',instance='0',job='app-server'} => 500 @[%v]",
+			"http_requests{group='canary',instance='1',job='api-server'} => 400 @[%v]",
+			"http_requests{group='canary',instance='0',job='api-server'} => 300 @[%v]",
+			"http_requests{group='production',instance='1',job='api-server'} => 200 @[%v]",
+			"http_requests{group='production',instance='0',job='api-server'} => 100 @[%v]",
+		},
+		checkOrder:     true,
+		fullRanges:     0,
+		intervalRanges: 8,
 	}, {
 		expr: "x{y='testvalue'}",
 		output: []string{
@@ -232,7 +262,7 @@ func TestExpressions(t *testing.T) {
 	storeMatrix(tieredStorage, testMatrix)
 	tieredStorage.Flush()
 
-	for _, exprTest := range expressionTests {
+	for i, exprTest := range expressionTests {
 		expectedLines := annotateWithTime(exprTest.output)
 
 		testExpr, err := LoadExprFromString(exprTest.expr)
@@ -241,21 +271,30 @@ func TestExpressions(t *testing.T) {
 			if exprTest.shouldFail {
 				continue
 			}
-			t.Errorf("Error during parsing: %v", err)
-			t.Errorf("Expression: %v", exprTest.expr)
+			t.Errorf("%d Error during parsing: %v", i, err)
+			t.Errorf("%d Expression: %v", i, exprTest.expr)
 		} else {
 			if exprTest.shouldFail {
-				t.Errorf("Test should fail, but didn't")
+				t.Errorf("%d Test should fail, but didn't", i)
 			}
 			failed := false
 			resultStr := ast.EvalToString(testExpr, testEvalTime, ast.TEXT)
 			resultLines := strings.Split(resultStr, "\n")
 
 			if len(exprTest.output) != len(resultLines) {
-				t.Errorf("Number of samples in expected and actual output don't match")
+				t.Errorf("%d Number of samples in expected and actual output don't match", i)
 				failed = true
 			}
-			for _, expectedSample := range expectedLines {
+
+			if exprTest.checkOrder {
+				for j, expectedSample := range expectedLines {
+					if resultLines[j] != expectedSample {
+						t.Errorf("%d.%d Expected sample '%v', got '%v'", i, j, resultLines[j], expectedSample)
+						failed = true
+					}
+				}
+			} else {
+				for j, expectedSample := range expectedLines {
 					found := false
 					for _, actualSample := range resultLines {
 						if actualSample == expectedSample {
@@ -263,25 +302,25 @@ func TestExpressions(t *testing.T) {
 						}
 					}
 					if !found {
-					t.Errorf("Couldn't find expected sample in output: '%v'",
-						expectedSample)
+						t.Errorf("%d.%d Couldn't find expected sample in output: '%v'", i, j, expectedSample)
 						failed = true
 					}
 				}
+			}
 
 			analyzer := ast.NewQueryAnalyzer()
 			analyzer.AnalyzeQueries(testExpr)
 			if exprTest.fullRanges != len(analyzer.FullRanges) {
-				t.Errorf("Count of full ranges didn't match: %v vs %v", exprTest.fullRanges, len(analyzer.FullRanges))
+				t.Errorf("%d Count of full ranges didn't match: %v vs %v", i, exprTest.fullRanges, len(analyzer.FullRanges))
 				failed = true
 			}
 			if exprTest.intervalRanges != len(analyzer.IntervalRanges) {
-				t.Errorf("Count of stepped ranges didn't match: %v vs %v", exprTest.intervalRanges, len(analyzer.IntervalRanges))
+				t.Errorf("%d Count of interval ranges didn't match: %v vs %v", i, exprTest.intervalRanges, len(analyzer.IntervalRanges))
 				failed = true
 			}
 
 			if failed {
-				t.Errorf("Expression: %v\n%v", exprTest.expr, vectorComparisonString(expectedLines, resultLines))
+				t.Errorf("%d Expression: %v\n%v", i, exprTest.expr, vectorComparisonString(expectedLines, resultLines))
 			}
 		}
 	}

utility/sort.go

@@ -0,0 +1,31 @@
+// Copyright 2013 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utility
+
+import (
+	"sort"
+)
+
+// ReverseSorter embeds a sort.Interface value and implements a reverse sort
+// over that value.
+type ReverseSorter struct {
+	// This embedded interface permits ReverseSorter to use the methods of
+	// another Interface implementation.
+	sort.Interface
+}
+
+// Less returns the opposite of the embedded implementation's Less method.
+func (r ReverseSorter) Less(i, j int) bool {
+	return r.Interface.Less(j, i)
+}