// 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 ast
import (
"errors"
"fmt"
"github.com/prometheus/prometheus/model"
"github.com/prometheus/prometheus/utility"
"sort"
"time"
)
type Function struct {
name string
argTypes []ExprType
returnType ExprType
callFn func(timestamp time.Time, view *viewAdapter, args []Node) interface{}
}
func (function *Function) CheckArgTypes(args []Node) error {
if len(function.argTypes) != len(args) {
return errors.New(
fmt.Sprintf("Wrong number of arguments to function %v(): %v expected, %v given",
function.name, len(function.argTypes), len(args)))
}
for idx, argType := range function.argTypes {
invalidType := false
var expectedType string
if _, ok := args[idx].(ScalarNode); argType == SCALAR && !ok {
invalidType = true
expectedType = "scalar"
}
if _, ok := args[idx].(VectorNode); argType == VECTOR && !ok {
invalidType = true
expectedType = "vector"
}
if _, ok := args[idx].(MatrixNode); argType == MATRIX && !ok {
invalidType = true
expectedType = "matrix"
}
if _, ok := args[idx].(StringNode); argType == STRING && !ok {
invalidType = true
expectedType = "string"
}
if invalidType {
return errors.New(
fmt.Sprintf("Wrong type for argument %v in function %v(), expected %v",
idx, function.name, expectedType))
}
}
return nil
}
// === time() model.SampleValue ===
func timeImpl(timestamp time.Time, view *viewAdapter, args []Node) interface{} {
return model.SampleValue(time.Now().Unix())
}
// === 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))
resultVector := Vector{}
// If we treat these metrics as counters, we need to fetch all values
// in the interval to find breaks in the timeseries' monotonicity.
// I.e. if a counter resets, we want to ignore that reset.
var matrixValue Matrix
if isCounter > 0 {
matrixValue = matrixNode.Eval(timestamp, view)
} else {
matrixValue = matrixNode.EvalBoundaries(timestamp, view)
}
for _, samples := range matrixValue {
counterCorrection := model.SampleValue(0)
lastValue := model.SampleValue(0)
for _, sample := range samples.Values {
currentValue := sample.Value
if currentValue < lastValue {
counterCorrection += lastValue - currentValue
}
lastValue = currentValue
}
resultValue := lastValue - samples.Values[0].Value + counterCorrection
targetInterval := args[0].(*MatrixLiteral).interval
sampledInterval := samples.Values[len(samples.Values)-1].Timestamp.Sub(samples.Values[0].Timestamp)
if sampledInterval == 0 {
// Only found one sample. Cannot compute a rate from this.
continue
}
// Correct for differences in target vs. actual delta interval.
//
// Above, we didn't actually calculate the delta for the specified target
// interval, but for an interval between the first and last found samples
// under the target interval, which will usually have less time between
// them. Depending on how many samples are found under a target interval,
// the delta results are distorted and temporal aliasing occurs (ugly
// bumps). This effect is corrected for below.
intervalCorrection := model.SampleValue(targetInterval) / model.SampleValue(sampledInterval)
resultValue *= intervalCorrection
resultSample := model.Sample{
Metric: samples.Metric,
Value: resultValue,
Timestamp: timestamp,
}
resultVector = append(resultVector, resultSample)
}
return resultVector
}
// === 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)
// TODO: could be other type of MatrixNode in the future (right now, only
// MatrixLiteral exists). Find a better way of getting the duration of a
// matrix, such as looking at the samples themselves.
interval := args[0].(*MatrixLiteral).interval
for i := range vector {
vector[i].Value /= model.SampleValue(interval / time.Second)
}
return vector
}
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{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "0",
},
Value: 10,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "1",
},
Value: 20,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "2",
},
Value: 30,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "3",
"group": "canary",
},
Value: 40,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "2",
"group": "canary",
},
Value: 40,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "3",
"group": "mytest",
},
Value: 40,
Timestamp: timestamp,
},
model.Sample{
Metric: model.Metric{
model.MetricNameLabel: "http_requests",
model.JobLabel: "api-server",
"instance": "3",
"group": "mytest",
},
Value: 40,
Timestamp: timestamp,
},
}
}
var functions = map[string]*Function{
"delta": {
name: "delta",
argTypes: []ExprType{MATRIX, SCALAR},
returnType: VECTOR,
callFn: deltaImpl,
},
"rate": {
name: "rate",
argTypes: []ExprType{MATRIX},
returnType: VECTOR,
callFn: rateImpl,
},
"sampleVector": {
name: "sampleVector",
argTypes: []ExprType{},
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) {
function, ok := functions[name]
if !ok {
return nil, errors.New(fmt.Sprintf("Couldn't find function %v()", name))
}
return function, nil
}