// NewAggregate takes a named aggregating function `[float64] => float64` and makes it into a MetricFunction.
func NewAggregate(name string, aggregator func([]float64) float64) function.MetricFunction {
return function.MetricFunction{
Name: name,
MinArguments: 1,
MaxArguments: 1,
AllowsGroupBy: true,
Compute: func(context function.EvaluationContext, args []function.Expression, groups []string) (function.Value, error) {
argument := args[0]
value, err := argument.Evaluate(context)
if err != nil {
return nil, err
}
seriesList, err := value.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
result := aggregate.AggregateBy(seriesList, aggregator, groups)
groupNames := make([]string, len(groups))
for i, group := range groups {
groupNames[i] += group
}
if len(groups) == 0 {
result.Name = fmt.Sprintf("%s(%s)", name, value.GetName())
} else {
result.Name = fmt.Sprintf("%s(%s group by %s)", name, value.GetName(), strings.Join(groupNames, ", "))
}
return function.SeriesListValue(result), nil
},
}
}
// NewFilter creates a new instance of a filtering function.
func NewFilter(name string, summary func([]float64) float64, ascending bool) function.MetricFunction {
return function.MetricFunction{
Name: name,
MinArguments: 2,
MaxArguments: 2,
Compute: func(context function.EvaluationContext, arguments []function.Expression, groups []string) (function.Value, error) {
value, err := arguments[0].Evaluate(context)
if err != nil {
return nil, err
}
// The value must be a SeriesList.
list, err := value.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
countValue, err := arguments[1].Evaluate(context)
if err != nil {
return nil, err
}
countFloat, err := countValue.ToScalar()
if err != nil {
return nil, err
}
// Round to the nearest integer.
count := int(countFloat + 0.5)
if count < 0 {
return nil, fmt.Errorf("expected positive count but got %d", count)
}
result := filter.FilterBy(list, count, summary, ascending)
result.Name = fmt.Sprintf("%s(%s, %d)", name, value.GetName(), count)
return function.SeriesListValue(result), nil
},
}
}
func (expr *metricFetchExpression) Evaluate(context function.EvaluationContext) (function.Value, error) {
// Merge predicates appropriately
var predicate api.Predicate
if context.Predicate == nil && expr.predicate == nil {
predicate = api.TruePredicate
} else if context.Predicate == nil {
predicate = expr.predicate
} else if expr.predicate == nil {
predicate = context.Predicate
} else {
predicate = &andPredicate{[]api.Predicate{expr.predicate, context.Predicate}}
}
metricTagSets, err := context.API.GetAllTags(api.MetricKey(expr.metricName))
if err != nil {
return nil, err
}
filtered := applyPredicates(metricTagSets, predicate)
ok := context.FetchLimit.Consume(len(filtered))
if !ok {
return nil, function.NewLimitError("fetch limit exceeded: too many series to fetch",
context.FetchLimit.Current(),
context.FetchLimit.Limit())
}
metrics := make([]api.TaggedMetric, len(filtered))
for i := range metrics {
metrics[i] = api.TaggedMetric{api.MetricKey(expr.metricName), filtered[i]}
}
serieslist, err := context.MultiBackend.FetchMultipleSeries(
api.FetchMultipleRequest{
metrics,
context.SampleMethod,
context.Timerange,
context.API,
context.Cancellable,
context.Profiler,
},
)
if err != nil {
return nil, err
}
serieslist.Name = expr.metricName
return function.SeriesListValue(serieslist), nil
}
// NewOperator creates a new binary operator function.
// the binary operators display a natural join semantic.
func NewOperator(op string, operator func(float64, float64) float64) function.MetricFunction {
return function.MetricFunction{
Name: op,
MinArguments: 2,
MaxArguments: 2,
Compute: func(context function.EvaluationContext, args []function.Expression, groups function.Groups) (function.Value, error) {
evaluated, err := function.EvaluateMany(context, args)
if err != nil {
return nil, err
}
leftValue := evaluated[0]
rightValue := evaluated[1]
leftList, err := leftValue.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
rightList, err := rightValue.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
joined := join.Join([]api.SeriesList{leftList, rightList})
result := make([]api.Timeseries, len(joined.Rows))
for i, row := range joined.Rows {
left := row.Row[0]
right := row.Row[1]
array := make([]float64, len(left.Values))
for j := 0; j < len(left.Values); j++ {
array[j] = operator(left.Values[j], right.Values[j])
}
result[i] = api.Timeseries{array, row.TagSet}
}
return function.SeriesListValue(api.SeriesList{
Series: result,
Timerange: context.Timerange,
Name: fmt.Sprintf("(%s %s %s)", leftValue.GetName(), op, rightValue.GetName()),
}), nil
},
}
}
// NewTransform takes a named transforming function `[float64], [value] => [float64]` and makes it into a MetricFunction.
func NewTransform(name string, parameterCount int, transformer func([]float64, []function.Value, float64) ([]float64, error)) function.MetricFunction {
return function.MetricFunction{
Name: name,
MinArguments: parameterCount + 1,
MaxArguments: parameterCount + 1,
Compute: func(context function.EvaluationContext, args []function.Expression, groups []string) (function.Value, error) {
listValue, err := args[0].Evaluate(context)
if err != nil {
return nil, err
}
list, err := listValue.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
parameters := make([]function.Value, parameterCount)
for i := range parameters {
parameters[i], err = args[i+1].Evaluate(context)
if err != nil {
return nil, err
}
}
result, err := transform.ApplyTransform(list, transformer, parameters)
if err != nil {
return nil, err
}
parameterNames := make([]string, len(parameters))
for i, param := range parameters {
parameterNames[i] = param.GetName()
}
if len(parameters) != 0 {
result.Name = fmt.Sprintf("%s(%s, %s)", name, listValue.GetName(), strings.Join(parameterNames, ", "))
} else {
result.Name = fmt.Sprintf("%s(%s)", name, listValue.GetName())
}
return function.SeriesListValue(result), nil
},
}
}
return nil, err
}
list, err := result.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
value, err := arguments[1].Evaluate(context)
if err != nil {
return nil, err
}
dropTag, err := value.ToString()
if err != nil {
return nil, err
}
// Drop the tag from the list.
return function.SeriesListValue(DropTag(list, dropTag)), nil
},
}
// SetFunction wraps up SetTag into a MetricFunction called "tag.set"
var SetFunction = function.MetricFunction{
Name: "tag.set",
MinArguments: 3,
MaxArguments: 3,
Compute: func(context function.EvaluationContext, arguments []function.Expression, groups function.Groups) (function.Value, error) {
result, err := arguments[0].Evaluate(context)
if err != nil {
return nil, err
}
list, err := result.ToSeriesList(context.Timerange)
if err != nil {
func (expr *LiteralSeriesExpression) Evaluate(context function.EvaluationContext) (function.Value, error) {
return function.SeriesListValue(expr.list), nil
}
func (expr *LiteralExpression) Evaluate(context function.EvaluationContext) (function.Value, error) {
return function.SeriesListValue(api.SeriesList{
Series: []api.Timeseries{api.Timeseries{expr.Values, api.NewTagSet()}},
Timerange: api.Timerange{},
}), nil
}
sum -= series.Values[i-limit]
count--
}
// Numerical error could (possibly) cause count == 0 but sum != 0.
if i-limit+1 >= 0 {
if count == 0 {
results[i-limit+1] = math.NaN()
} else {
results[i-limit+1] = sum / float64(count)
}
}
}
list.Series[index].Values = results
}
list.Name = fmt.Sprintf("transform.moving_average(%s, %s)", listValue.GetName(), sizeValue.GetName())
return function.SeriesListValue(list), nil
},
}
var Alias = function.MetricFunction{
Name: "transform.alias",
MinArguments: 2,
MaxArguments: 2,
Compute: func(context function.EvaluationContext, arguments []function.Expression, groups []string) (function.Value, error) {
value, err := arguments[0].Evaluate(context)
if err != nil {
return nil, err
}
list, err := value.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
// NewOperator creates a new binary operator function.
// the binary operators display a natural join semantic.
func NewOperator(op string, operator func(float64, float64) float64) function.MetricFunction {
return function.MetricFunction{
Name: op,
MinArguments: 2,
MaxArguments: 2,
Compute: func(context function.EvaluationContext, args []function.Expression, groups []string) (function.Value, error) {
leftChannel := make(chan function.Value, 1)
rightChannel := make(chan function.Value, 1)
errs := make(chan error, 2)
go func() {
leftValue, err := args[0].Evaluate(context)
leftChannel <- leftValue
errs <- err
}()
go func() {
rightValue, err := args[1].Evaluate(context)
rightChannel <- rightValue
errs <- err
}()
err := <-errs
if err != nil {
return nil, err
}
err = <-errs
if err != nil {
return nil, err
}
leftValue := <-leftChannel
rightValue := <-rightChannel
leftList, err := leftValue.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
rightList, err := rightValue.ToSeriesList(context.Timerange)
if err != nil {
return nil, err
}
joined := join.Join([]api.SeriesList{leftList, rightList})
result := make([]api.Timeseries, len(joined.Rows))
for i, row := range joined.Rows {
left := row.Row[0]
right := row.Row[1]
array := make([]float64, len(left.Values))
for j := 0; j < len(left.Values); j++ {
array[j] = operator(left.Values[j], right.Values[j])
}
result[i] = api.Timeseries{array, row.TagSet}
}
return function.SeriesListValue(api.SeriesList{
Series: result,
Timerange: context.Timerange,
Name: fmt.Sprintf("(%s %s %s)", leftValue.GetName(), op, rightValue.GetName()),
}), nil
},
}
}