VictoriaMetrics/app/vmselect/promql/exec.go

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package promql
import (
"flag"
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"fmt"
"math"
"sort"
"sync"
"sync/atomic"
"time"
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"github.com/VictoriaMetrics/VictoriaMetrics/app/vmselect/netstorage"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
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"github.com/VictoriaMetrics/metrics"
)
var logSlowQueryDuration = flag.Duration("search.logSlowQueryDuration", 5*time.Second, "Log queries with execution time exceeding this value. Zero disables slow query logging")
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// ExpandWithExprs expands WITH expressions inside q and returns the resulting
// PromQL without WITH expressions.
func ExpandWithExprs(q string) (string, error) {
e, err := parsePromQLWithCache(q)
if err != nil {
return "", err
}
buf := e.AppendString(nil)
return string(buf), nil
}
// Exec executes q for the given ec.
func Exec(ec *EvalConfig, q string, isFirstPointOnly bool) ([]netstorage.Result, error) {
if *logSlowQueryDuration > 0 {
startTime := time.Now()
defer func() {
d := time.Since(startTime)
if d >= *logSlowQueryDuration {
logger.Infof("slow query according to -search.logSlowQueryDuration=%s: duration=%s, start=%d, end=%d, step=%d, query=%q",
*logSlowQueryDuration, d, ec.Start/1000, ec.End/1000, ec.Step/1000, q)
}
}()
}
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ec.validate()
e, err := parsePromQLWithCache(q)
if err != nil {
return nil, err
}
// Add an additional point to the end. This point is used
// in calculating the last value for rate, deriv, increase
// and delta funcs.
ec.End += ec.Step
rv, err := evalExpr(ec, e)
if err != nil {
return nil, err
}
// Remove the additional point at the end.
for _, ts := range rv {
ts.Values = ts.Values[:len(ts.Values)-1]
// ts.Timestamps may be shared between timeseries, so truncate it with len(ts.Values) instead of len(ts.Timestamps)-1
ts.Timestamps = ts.Timestamps[:len(ts.Values)]
}
ec.End -= ec.Step
if isFirstPointOnly {
// Remove all the points except the first one from every time series.
for _, ts := range rv {
ts.Values = ts.Values[:1]
ts.Timestamps = ts.Timestamps[:1]
}
}
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maySort := maySortResults(e, rv)
result, err := timeseriesToResult(rv, maySort)
if err != nil {
return nil, err
}
return result, err
}
func maySortResults(e expr, tss []*timeseries) bool {
if len(tss) > 100 {
// There is no sense in sorting a lot of results
return false
}
fe, ok := e.(*funcExpr)
if !ok {
return true
}
switch fe.Name {
case "sort", "sort_desc":
return false
default:
return true
}
}
func timeseriesToResult(tss []*timeseries, maySort bool) ([]netstorage.Result, error) {
tss = removeNaNs(tss)
result := make([]netstorage.Result, len(tss))
m := make(map[string]bool)
bb := bbPool.Get()
for i, ts := range tss {
bb.B = marshalMetricNameSorted(bb.B[:0], &ts.MetricName)
if m[string(bb.B)] {
return nil, fmt.Errorf(`duplicate output timeseries: %s%s`, ts.MetricName.MetricGroup, stringMetricName(&ts.MetricName))
}
m[string(bb.B)] = true
rs := &result[i]
rs.MetricNameMarshaled = append(rs.MetricNameMarshaled[:0], bb.B...)
rs.MetricName.CopyFrom(&ts.MetricName)
rs.Values = append(rs.Values[:0], ts.Values...)
rs.Timestamps = append(rs.Timestamps[:0], ts.Timestamps...)
}
bbPool.Put(bb)
if maySort {
sort.Slice(result, func(i, j int) bool {
return string(result[i].MetricNameMarshaled) < string(result[j].MetricNameMarshaled)
})
}
return result, nil
}
func removeNaNs(tss []*timeseries) []*timeseries {
rvs := tss[:0]
for _, ts := range tss {
nans := 0
for _, v := range ts.Values {
if math.IsNaN(v) {
nans++
}
}
if nans == len(ts.Values) {
// Skip timeseries with all NaNs.
continue
}
rvs = append(rvs, ts)
}
return rvs
}
func parsePromQLWithCache(q string) (expr, error) {
pcv := parseCacheV.Get(q)
if pcv == nil {
e, err := parsePromQL(q)
pcv = &parseCacheValue{
e: e,
err: err,
}
parseCacheV.Put(q, pcv)
}
if pcv.err != nil {
return nil, pcv.err
}
return pcv.e, nil
}
var parseCacheV = func() *parseCache {
pc := &parseCache{
m: make(map[string]*parseCacheValue),
}
metrics.NewGauge(`vm_cache_requests_total{type="promql/parse"}`, func() float64 {
return float64(pc.Requests())
})
metrics.NewGauge(`vm_cache_misses_total{type="promql/parse"}`, func() float64 {
return float64(pc.Misses())
})
metrics.NewGauge(`vm_cache_entries{type="promql/parse"}`, func() float64 {
return float64(pc.Len())
})
return pc
}()
const parseCacheMaxLen = 10e3
type parseCacheValue struct {
e expr
err error
}
type parseCache struct {
m map[string]*parseCacheValue
mu sync.RWMutex
requests uint64
misses uint64
}
func (pc *parseCache) Requests() uint64 {
return atomic.LoadUint64(&pc.requests)
}
func (pc *parseCache) Misses() uint64 {
return atomic.LoadUint64(&pc.misses)
}
func (pc *parseCache) Len() uint64 {
pc.mu.RLock()
n := len(pc.m)
pc.mu.RUnlock()
return uint64(n)
}
func (pc *parseCache) Get(q string) *parseCacheValue {
atomic.AddUint64(&pc.requests, 1)
pc.mu.RLock()
pcv := pc.m[q]
pc.mu.RUnlock()
if pcv == nil {
atomic.AddUint64(&pc.misses, 1)
}
return pcv
}
func (pc *parseCache) Put(q string, pcv *parseCacheValue) {
pc.mu.Lock()
overflow := len(pc.m) - parseCacheMaxLen
if overflow > 0 {
// Remove 10% of items from the cache.
overflow = int(float64(len(pc.m)) * 0.1)
for k := range pc.m {
delete(pc.m, k)
overflow--
if overflow <= 0 {
break
}
}
}
pc.m[q] = pcv
pc.mu.Unlock()
}