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expr.go
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expr.go
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package expr
import (
"context"
"github.com/ansel1/merry"
pb "github.com/go-graphite/protocol/carbonapi_v3_pb"
"github.com/go-graphite/carbonapi/cmd/carbonapi/config"
_ "github.com/go-graphite/carbonapi/expr/functions"
"github.com/go-graphite/carbonapi/expr/helper"
"github.com/go-graphite/carbonapi/expr/metadata"
"github.com/go-graphite/carbonapi/expr/types"
"github.com/go-graphite/carbonapi/pkg/parser"
utilctx "github.com/go-graphite/carbonapi/util/ctx"
)
type evaluator struct{}
func (eval evaluator) Fetch(ctx context.Context, exprs []parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) (map[parser.MetricRequest][]*types.MetricData, error) {
config.Config.Limiter.Enter()
defer config.Config.Limiter.Leave()
multiFetchRequest := pb.MultiFetchRequest{}
metricRequestCache := make(map[string]parser.MetricRequest)
maxDataPoints := utilctx.GetMaxDatapoints(ctx)
// values related to this particular `target=`
targetValues := make(map[parser.MetricRequest][]*types.MetricData)
haveFallbackSeries := false
for _, exp := range exprs {
for _, m := range exp.Metrics(from, until) {
fetchRequest := pb.FetchRequest{
Name: m.Metric,
PathExpression: m.Metric,
StartTime: m.From,
StopTime: m.Until,
MaxDataPoints: maxDataPoints,
}
metricRequest := parser.MetricRequest{
Metric: fetchRequest.PathExpression,
From: fetchRequest.StartTime,
Until: fetchRequest.StopTime,
}
if exp.Target() == "fallbackSeries" {
haveFallbackSeries = true
}
// avoid multiple requests in a function, E.g divideSeries(a.b, a.b)
if cachedMetricRequest, ok := metricRequestCache[m.Metric]; ok &&
cachedMetricRequest.From == metricRequest.From &&
cachedMetricRequest.Until == metricRequest.Until {
continue
}
// avoid multiple requests in a http request, E.g render?target=a.b&target=a.b
if _, ok := values[metricRequest]; ok {
targetValues[metricRequest] = nil
continue
}
// avoid multiple requests from the same target, e.g. target=max(a,asPercent(holtWintersForecast(a),a))
if _, ok := targetValues[metricRequest]; ok {
continue
}
metricRequestCache[m.Metric] = metricRequest
targetValues[metricRequest] = nil
multiFetchRequest.Metrics = append(multiFetchRequest.Metrics, fetchRequest)
}
}
if len(multiFetchRequest.Metrics) > 0 {
metrics, _, err := config.Config.ZipperInstance.Render(ctx, multiFetchRequest)
// If we had only partial result, we want to do our best to actually do our job
if err != nil && merry.HTTPCode(err) >= 400 && !haveFallbackSeries {
return nil, err
}
for _, metric := range metrics {
metricRequest := metricRequestCache[metric.PathExpression]
if metric.RequestStartTime != 0 && metric.RequestStopTime != 0 {
metricRequest.From = metric.RequestStartTime
metricRequest.Until = metric.RequestStopTime
}
data, ok := values[metricRequest]
if !ok {
data = make([]*types.MetricData, 0, 1)
}
values[metricRequest] = append(data, metric)
}
}
for m := range targetValues {
targetValues[m] = values[m]
}
if config.Config.ZipperInstance.ScaleToCommonStep() {
targetValues = helper.ScaleValuesToCommonStep(targetValues)
}
return targetValues, nil
}
// Eval evaluates expressions.
func (eval evaluator) Eval(ctx context.Context, exp parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) (results []*types.MetricData, err error) {
rewritten, targets, err := RewriteExpr(ctx, exp, from, until, values)
if err != nil {
return nil, err
}
if rewritten {
for _, target := range targets {
exp, _, err = parser.ParseExpr(target)
if err != nil {
return nil, err
}
targetValues, err := eval.Fetch(ctx, []parser.Expr{exp}, from, until, values)
if err != nil {
return nil, err
}
result, err := eval.Eval(ctx, exp, from, until, targetValues)
if err != nil {
return nil, err
}
results = append(results, result...)
}
return results, nil
}
return EvalExpr(ctx, exp, from, until, values)
}
var _evaluator = evaluator{}
func init() {
helper.SetEvaluator(_evaluator)
metadata.SetEvaluator(_evaluator)
}
// FetchAndEvalExp fetch data and evaluates expressions
func FetchAndEvalExp(ctx context.Context, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, merry.Error) {
targetValues, err := _evaluator.Fetch(ctx, []parser.Expr{e}, from, until, values)
if err != nil {
return nil, merry.Wrap(err)
}
res, err := _evaluator.Eval(ctx, e, from, until, targetValues)
if err != nil {
return nil, merry.Wrap(err)
}
for mReq := range values {
SortMetrics(values[mReq], mReq)
}
return res, nil
}
func FetchAndEvalExprs(ctx context.Context, exprs []parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, map[string]merry.Error) {
targetValues, err := _evaluator.Fetch(ctx, exprs, from, until, values)
if err != nil {
return nil, map[string]merry.Error{"*": merry.Wrap(err)}
}
res := make([]*types.MetricData, 0, len(exprs))
var errors map[string]merry.Error
for _, exp := range exprs {
evaluationResult, err := _evaluator.Eval(ctx, exp, from, until, targetValues)
if err != nil {
if errors == nil {
errors = make(map[string]merry.Error)
}
errors[exp.Target()] = merry.Wrap(err)
}
res = append(res, evaluationResult...)
}
for mReq := range values {
SortMetrics(values[mReq], mReq)
}
return res, errors
}
// EvalExpr is the main expression evaluator.
func EvalExpr(ctx context.Context, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, error) {
if e.IsName() {
return values[parser.MetricRequest{Metric: e.Target(), From: from, Until: until}], nil
} else if e.IsConst() {
p := types.MetricData{
FetchResponse: pb.FetchResponse{
Name: e.ToString(),
Values: []float64{e.FloatValue()},
StartTime: from,
StopTime: until,
StepTime: until - from,
},
Tags: map[string]string{"name": e.ToString()},
}
return []*types.MetricData{&p}, nil
}
// evaluate the function
// all functions have arguments -- check we do too
if e.ArgsLen() == 0 {
err := merry.WithMessagef(parser.ErrMissingArgument, "target=%s: %s", e.Target(), parser.ErrMissingArgument)
return nil, merry.WithHTTPCode(err, 400)
}
metadata.FunctionMD.RLock()
f, ok := metadata.FunctionMD.Functions[e.Target()]
metadata.FunctionMD.RUnlock()
if ok {
v, err := f.Do(ctx, e, from, until, values)
if err != nil {
err = merry.WithMessagef(err, "function=%s: %s", e.Target(), err.Error())
if merry.Is(
err,
parser.ErrMissingExpr,
parser.ErrMissingComma,
parser.ErrMissingQuote,
parser.ErrUnexpectedCharacter,
parser.ErrBadType,
parser.ErrMissingArgument,
parser.ErrMissingTimeseries,
parser.ErrMissingValues,
parser.ErrUnknownTimeUnits,
parser.ErrInvalidArg,
) {
err = merry.WithHTTPCode(err, 400)
}
}
return v, err
}
return nil, merry.WithHTTPCode(helper.ErrUnknownFunction(e.Target()), 400)
}
// RewriteExpr expands targets that use applyByNode into a new list of targets.
// eg:
// applyByNode(foo*, 1, "%") -> (true, ["foo1", "foo2"], nil)
// sumSeries(foo) -> (false, nil, nil)
// Assumes that applyByNode only appears as the outermost function.
func RewriteExpr(ctx context.Context, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) (bool, []string, error) {
if e.IsFunc() {
metadata.FunctionMD.RLock()
f, ok := metadata.FunctionMD.RewriteFunctions[e.Target()]
metadata.FunctionMD.RUnlock()
if ok {
return f.Do(ctx, e, from, until, values)
}
}
return false, nil, nil
}