SSE: Threshold expression to use simple functions (#86062)
* replace math expression with predicates
This commit is contained in:
Yuri Tseretyan
+95
-38
@@ -13,14 +13,19 @@ import (
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"github.com/grafana/grafana/pkg/expr/mathexp"
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"github.com/grafana/grafana/pkg/infra/tracing"
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"github.com/grafana/grafana/pkg/services/featuremgmt"
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"github.com/grafana/grafana/pkg/util"
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)
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type predicate interface {
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Eval(f float64) bool
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}
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type ThresholdCommand struct {
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ReferenceVar string
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RefID string
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ThresholdFunc ThresholdType
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Conditions []float64
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Invert bool
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predicate predicate
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}
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// +enum
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@@ -43,15 +48,28 @@ var (
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)
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func NewThresholdCommand(refID, referenceVar string, thresholdFunc ThresholdType, conditions []float64) (*ThresholdCommand, error) {
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var predicate predicate
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switch thresholdFunc {
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case ThresholdIsOutsideRange, ThresholdIsWithinRange:
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case ThresholdIsOutsideRange:
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if len(conditions) < 2 {
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return nil, fmt.Errorf("incorrect number of arguments: got %d but need 2", len(conditions))
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return nil, fmt.Errorf("incorrect number of arguments for threshold function '%s': got %d but need 2", thresholdFunc, len(conditions))
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}
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case ThresholdIsAbove, ThresholdIsBelow:
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predicate = outsideRangePredicate{left: conditions[0], right: conditions[1]}
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case ThresholdIsWithinRange:
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if len(conditions) < 2 {
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return nil, fmt.Errorf("incorrect number of arguments for threshold function '%s': got %d but need 2", thresholdFunc, len(conditions))
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}
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predicate = withinRangePredicate{left: conditions[0], right: conditions[1]}
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case ThresholdIsAbove:
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if len(conditions) < 1 {
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return nil, fmt.Errorf("incorrect number of arguments: got %d but need 1", len(conditions))
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return nil, fmt.Errorf("incorrect number of arguments for threshold function '%s': got %d but need 1", thresholdFunc, len(conditions))
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}
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predicate = greaterThanPredicate{value: conditions[0]}
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case ThresholdIsBelow:
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if len(conditions) < 1 {
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return nil, fmt.Errorf("incorrect number of arguments for threshold function '%s': got %d but need 1", thresholdFunc, len(conditions))
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}
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predicate = lessThanPredicate{value: conditions[0]}
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default:
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return nil, fmt.Errorf("expected threshold function to be one of [%s], got %s", strings.Join(supportedThresholdFuncs, ", "), thresholdFunc)
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}
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@@ -60,7 +78,7 @@ func NewThresholdCommand(refID, referenceVar string, thresholdFunc ThresholdType
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RefID: refID,
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ReferenceVar: referenceVar,
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ThresholdFunc: thresholdFunc,
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Conditions: conditions,
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predicate: predicate,
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}, nil
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}
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@@ -114,46 +132,51 @@ func (tc *ThresholdCommand) NeedsVars() []string {
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return []string{tc.ReferenceVar}
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}
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func (tc *ThresholdCommand) Execute(ctx context.Context, now time.Time, vars mathexp.Vars, tracer tracing.Tracer) (mathexp.Results, error) {
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mathExpression, err := createMathExpression(tc.ReferenceVar, tc.ThresholdFunc, tc.Conditions, tc.Invert)
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if err != nil {
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return mathexp.Results{}, err
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func (tc *ThresholdCommand) Execute(_ context.Context, _ time.Time, vars mathexp.Vars, _ tracing.Tracer) (mathexp.Results, error) {
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eval := func(maybeValue *float64) *float64 {
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if maybeValue == nil {
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return nil
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}
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result := tc.predicate.Eval(*maybeValue)
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if tc.Invert {
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result = !result
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}
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if result {
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return util.Pointer(float64(1))
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}
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return util.Pointer(float64(0))
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}
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mathCommand, err := NewMathCommand(tc.RefID, mathExpression)
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if err != nil {
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return mathexp.Results{}, err
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refVarResult := vars[tc.ReferenceVar]
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newRes := mathexp.Results{Values: make(mathexp.Values, 0, len(refVarResult.Values))}
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for _, val := range refVarResult.Values {
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switch v := val.(type) {
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case mathexp.Series:
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s := mathexp.NewSeries(tc.RefID, v.GetLabels(), v.Len())
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for i := 0; i < v.Len(); i++ {
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t, value := v.GetPoint(i)
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s.SetPoint(i, t, eval(value))
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}
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newRes.Values = append(newRes.Values, s)
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case mathexp.Number:
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copyV := mathexp.NewNumber(tc.RefID, v.GetLabels())
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copyV.SetValue(eval(v.GetFloat64Value()))
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newRes.Values = append(newRes.Values, copyV)
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case mathexp.Scalar:
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copyV := mathexp.NewScalar(tc.RefID, eval(v.GetFloat64Value()))
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newRes.Values = append(newRes.Values, copyV)
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case mathexp.NoData:
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newRes.Values = append(newRes.Values, mathexp.NewNoData())
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default:
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return newRes, fmt.Errorf("unsupported format of the input data, got type %v", val.Type())
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}
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}
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return mathCommand.Execute(ctx, now, vars, tracer)
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return newRes, nil
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}
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func (tc *ThresholdCommand) Type() string {
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return TypeThreshold.String()
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}
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// createMathExpression converts all the info we have about a "threshold" expression in to a Math expression
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func createMathExpression(referenceVar string, thresholdFunc ThresholdType, args []float64, invert bool) (string, error) {
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var exp string
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switch thresholdFunc {
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case ThresholdIsAbove:
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exp = fmt.Sprintf("${%s} > %f", referenceVar, args[0])
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case ThresholdIsBelow:
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exp = fmt.Sprintf("${%s} < %f", referenceVar, args[0])
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case ThresholdIsWithinRange:
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exp = fmt.Sprintf("${%s} > %f && ${%s} < %f", referenceVar, args[0], referenceVar, args[1])
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case ThresholdIsOutsideRange:
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exp = fmt.Sprintf("${%s} < %f || ${%s} > %f", referenceVar, args[0], referenceVar, args[1])
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default:
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return "", fmt.Errorf("failed to evaluate threshold expression: no such threshold function %s", thresholdFunc)
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}
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if invert {
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return fmt.Sprintf("!(%s)", exp), nil
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}
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return exp, nil
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}
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func IsSupportedThresholdFunc(name string) bool {
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isSupported := false
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@@ -237,3 +260,37 @@ func getConditionForHysteresisCommand(query map[string]any) (map[string]any, err
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}
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return condition, nil
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}
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type withinRangePredicate struct {
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left float64
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right float64
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}
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func (r withinRangePredicate) Eval(f float64) bool {
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return f > r.left && f < r.right
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}
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type outsideRangePredicate struct {
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left float64
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right float64
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}
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func (r outsideRangePredicate) Eval(f float64) bool {
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return f < r.left || f > r.right
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}
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type lessThanPredicate struct {
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value float64
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}
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func (r lessThanPredicate) Eval(f float64) bool {
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return f < r.value
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}
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type greaterThanPredicate struct {
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value float64
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}
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func (r greaterThanPredicate) Eval(f float64) bool {
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return f > r.value
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}
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