[query] Implemented the Graphite timeSlice function

src/query/graphite/native/builtin_functions.go

@@ -32,6 +32,7 @@ import (
 
 	"github.com/m3db/m3/src/query/graphite/common"
 	"github.com/m3db/m3/src/query/graphite/errors"
+	"github.com/m3db/m3/src/query/graphite/graphite"
 	"github.com/m3db/m3/src/query/graphite/ts"
 	"github.com/m3db/m3/src/query/util"
 )
@@ -242,6 +243,50 @@ func timeShift(
 	}, nil
 }
 
+// timeSlice takes one metric or a wildcard metric, followed by a quoted string with the time to start the line and
+// another quoted string with the time to end the line. The start and end times are inclusive.
+// Useful for filtering out a part of a series of data from a wider range of data.
+func timeSlice(ctx *common.Context, inputPath singlePathSpec, start string, end string) (ts.SeriesList, error) {
+	var (
+		now = time.Now()
+		tzOffsetForAbsoluteTime time.Duration
+	)
+	startTime, err := graphite.ParseTime(start, now, tzOffsetForAbsoluteTime)
+	if err != nil {
+		return ts.NewSeriesList(), err
+	}
+	endTime, err := graphite.ParseTime(end, now, tzOffsetForAbsoluteTime)
+	if err != nil {
+		return ts.NewSeriesList(), err
+	}
+
+	input := ts.SeriesList(inputPath)
+	output := make([]*ts.Series, 0, input.Len())
+
+	for _, series := range input.Values {
+		stepDuration := time.Duration(series.MillisPerStep()) * time.Millisecond
+		truncatedValues := ts.NewValues(ctx, series.MillisPerStep(), series.Len())
+
+		currentTime := series.StartTime()
+		for i := 0; i < series.Len(); i++ {
+			equalOrAfterStart := currentTime.Equal(startTime) || currentTime.After(startTime)
+			beforeOrEqualEnd := currentTime.Before(endTime) || currentTime.Equal(endTime)
+			if equalOrAfterStart && beforeOrEqualEnd {
+				truncatedValues.SetValueAt(i, series.ValueAtTime(currentTime))
+			}
+			currentTime = currentTime.Add(stepDuration)
+		}
+
+		slicedSeries := ts.NewSeries(ctx, series.Name(), series.StartTime(), truncatedValues)
+		renamedSlicedSeries := slicedSeries.RenamedTo(fmt.Sprintf("timeSlice(%s, %s, %s)", slicedSeries.Name(), start, end))
+		output = append(output, renamedSlicedSeries)
+	}
+	input.Values = output
+	return input, nil
+}
+
+
+
 // absolute returns the absolute value of each element in the series.
 func absolute(ctx *common.Context, input singlePathSpec) (ts.SeriesList, error) {
 	return transform(ctx, input,
@@ -1974,6 +2019,9 @@ func init() {
 	MustRegisterFunction(timeShift).WithDefaultParams(map[uint8]interface{}{
 		3: true, // resetEnd
 	})
+	MustRegisterFunction(timeSlice).WithDefaultParams(map[uint8]interface{}{
+		3: "now", // endTime
+	})
 	MustRegisterFunction(transformNull).WithDefaultParams(map[uint8]interface{}{
 		2: 0.0, // defaultValue
 	})

src/query/graphite/native/builtin_functions_test.go

@@ -642,6 +642,43 @@ func testMovingFunction(t *testing.T, target, expectedName string, values, boots
 		expected, res.Values)
 }
 
+var (
+	testGeneralFunctionStart     = time.Now().Add(time.Minute * -11).Truncate(time.Minute)
+	testGeneralFunctionEnd       = time.Now().Add(time.Minute * -3).Truncate(time.Minute)
+)
+
+// testGeneralFunction is a copy of testMovingFunction but without any logic for bootstrapping values
+func testGeneralFunction(t *testing.T, target, expectedName string, values, output []float64) {
+	ctx := common.NewTestContext()
+	defer ctx.Close()
+
+	engine := NewEngine(
+		&common.MovingFunctionStorage{
+			StepMillis:     60000,
+			Values:         values,
+		},
+	)
+	phonyContext := common.NewContext(common.ContextOptions{
+		Start:  testGeneralFunctionStart,
+		End:    testGeneralFunctionEnd,
+		Engine: engine,
+	})
+
+	expr, err := phonyContext.Engine.(*Engine).Compile(target)
+	require.NoError(t, err)
+	res, err := expr.Execute(phonyContext)
+	require.NoError(t, err)
+	var expected []common.TestSeries
+	if output != nil {
+		expectedSeries := common.TestSeries{
+			Name: expectedName,
+			Data: output,
+		}
+		expected = append(expected, expectedSeries)
+	}
+	common.CompareOutputsAndExpected(t, 60000, testGeneralFunctionStart, expected, res.Values)
+}
+
 func TestMovingAverageSuccess(t *testing.T) {
 	values := []float64{12.0, 19.0, -10.0, math.NaN(), 10.0}
 	bootstrap := []float64{3.0, 4.0, 5.0}
@@ -2840,6 +2877,13 @@ func TestTimeShift(t *testing.T) {
 		[]common.TestSeries{expected}, res.Values)
 }
 
+func TestTimeSlice(t *testing.T) {
+	values := []float64{math.NaN(),1.0,2.0,3.0,math.NaN(),5.0,6.0,math.NaN(),7.0,8.0,9.0}
+	expected := []float64{math.NaN(),math.NaN(),math.NaN(),3.0,math.NaN(),5.0,6.0,math.NaN(),7.0,math.NaN(),math.NaN()}
+
+	testGeneralFunction(t, "timeSlice(foo.bar.baz, '-9min','-3min')", "timeSlice(foo.bar.baz, -9min, -3min)", values, expected)
+}
+
 func TestDashed(t *testing.T) {
 	ctx := common.NewTestContext()
 	defer ctx.Close()
@@ -2990,6 +3034,7 @@ func TestFunctionsRegistered(t *testing.T) {
 		"time",
 		"timeFunction",
 		"timeShift",
+		"timeSlice",
 		"transformNull",
 		"weightedAverage",
 	}