prometheus/rules/ast/query_analyzer.go
2015-02-18 02:45:54 +01:00

230 lines
7.2 KiB
Go

// Copyright 2013 The Prometheus Authors
// 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 (
"time"
clientmodel "github.com/prometheus/client_golang/model"
"github.com/prometheus/prometheus/stats"
"github.com/prometheus/prometheus/storage/local"
)
// preloadTimes tracks which instants or ranges to preload for a set of
// fingerprints. One of these structs is collected for each offset by the query
// analyzer.
type preloadTimes struct {
// Instants require single samples to be loaded along the entire query
// range, with intervals between the samples corresponding to the query
// resolution.
instants map[clientmodel.Fingerprint]struct{}
// Ranges require loading a range of samples at each resolution step,
// stretching backwards from the current evaluation timestamp. The length of
// the range into the past is given by the duration, as in "foo[5m]".
ranges map[clientmodel.Fingerprint]time.Duration
}
// A queryAnalyzer recursively traverses the AST to look for any nodes
// which will need data from the datastore. Instantiate with
// newQueryAnalyzer.
type queryAnalyzer struct {
// Tracks one set of times to preload per offset that occurs in the query
// expression.
offsetPreloadTimes map[time.Duration]preloadTimes
// The underlying storage to which the query will be applied. Needed for
// extracting timeseries fingerprint information during query analysis.
storage local.Storage
}
// newQueryAnalyzer returns a pointer to a newly instantiated
// queryAnalyzer. The storage is needed to extract timeseries
// fingerprint information during query analysis.
func newQueryAnalyzer(storage local.Storage) *queryAnalyzer {
return &queryAnalyzer{
offsetPreloadTimes: map[time.Duration]preloadTimes{},
storage: storage,
}
}
func (analyzer *queryAnalyzer) getPreloadTimes(offset time.Duration) preloadTimes {
if _, ok := analyzer.offsetPreloadTimes[offset]; !ok {
analyzer.offsetPreloadTimes[offset] = preloadTimes{
instants: map[clientmodel.Fingerprint]struct{}{},
ranges: map[clientmodel.Fingerprint]time.Duration{},
}
}
return analyzer.offsetPreloadTimes[offset]
}
// visit implements the visitor interface.
func (analyzer *queryAnalyzer) visit(node Node) {
switch n := node.(type) {
case *VectorSelector:
pt := analyzer.getPreloadTimes(n.offset)
fingerprints := analyzer.storage.GetFingerprintsForLabelMatchers(n.labelMatchers)
n.fingerprints = fingerprints
for _, fp := range fingerprints {
// Only add the fingerprint to the instants if not yet present in the
// ranges. Ranges always contain more points and span more time than
// instants for the same offset.
if _, alreadyInRanges := pt.ranges[fp]; !alreadyInRanges {
pt.instants[fp] = struct{}{}
}
n.metrics[fp] = analyzer.storage.GetMetricForFingerprint(fp)
}
case *MatrixSelector:
pt := analyzer.getPreloadTimes(n.offset)
fingerprints := analyzer.storage.GetFingerprintsForLabelMatchers(n.labelMatchers)
n.fingerprints = fingerprints
for _, fp := range fingerprints {
if pt.ranges[fp] < n.interval {
pt.ranges[fp] = n.interval
// Delete the fingerprint from the instants. Ranges always contain more
// points and span more time than instants, so we don't need to track
// an instant for the same fingerprint, should we have one.
delete(pt.instants, fp)
}
n.metrics[fp] = analyzer.storage.GetMetricForFingerprint(fp)
}
}
}
type iteratorInitializer struct {
storage local.Storage
}
func (i *iteratorInitializer) visit(node Node) {
switch n := node.(type) {
case *VectorSelector:
for _, fp := range n.fingerprints {
n.iterators[fp] = i.storage.NewIterator(fp)
}
case *MatrixSelector:
for _, fp := range n.fingerprints {
n.iterators[fp] = i.storage.NewIterator(fp)
}
}
}
func prepareInstantQuery(node Node, timestamp clientmodel.Timestamp, storage local.Storage, queryStats *stats.TimerGroup) (local.Preloader, error) {
totalTimer := queryStats.GetTimer(stats.TotalEvalTime)
analyzeTimer := queryStats.GetTimer(stats.QueryAnalysisTime).Start()
analyzer := newQueryAnalyzer(storage)
Walk(analyzer, node)
analyzeTimer.Stop()
preloadTimer := queryStats.GetTimer(stats.PreloadTime).Start()
p := storage.NewPreloader()
for offset, pt := range analyzer.offsetPreloadTimes {
ts := timestamp.Add(-offset)
for fp, rangeDuration := range pt.ranges {
if et := totalTimer.ElapsedTime(); et > *queryTimeout {
preloadTimer.Stop()
p.Close()
return nil, queryTimeoutError{et}
}
if err := p.PreloadRange(fp, ts.Add(-rangeDuration), ts, *stalenessDelta); err != nil {
preloadTimer.Stop()
p.Close()
return nil, err
}
}
for fp := range pt.instants {
if et := totalTimer.ElapsedTime(); et > *queryTimeout {
preloadTimer.Stop()
p.Close()
return nil, queryTimeoutError{et}
}
if err := p.PreloadRange(fp, ts, ts, *stalenessDelta); err != nil {
preloadTimer.Stop()
p.Close()
return nil, err
}
}
}
preloadTimer.Stop()
ii := &iteratorInitializer{
storage: storage,
}
Walk(ii, node)
return p, nil
}
func prepareRangeQuery(node Node, start clientmodel.Timestamp, end clientmodel.Timestamp, interval time.Duration, storage local.Storage, queryStats *stats.TimerGroup) (local.Preloader, error) {
totalTimer := queryStats.GetTimer(stats.TotalEvalTime)
analyzeTimer := queryStats.GetTimer(stats.QueryAnalysisTime).Start()
analyzer := newQueryAnalyzer(storage)
Walk(analyzer, node)
analyzeTimer.Stop()
preloadTimer := queryStats.GetTimer(stats.PreloadTime).Start()
p := storage.NewPreloader()
for offset, pt := range analyzer.offsetPreloadTimes {
offsetStart := start.Add(-offset)
offsetEnd := end.Add(-offset)
for fp, rangeDuration := range pt.ranges {
if et := totalTimer.ElapsedTime(); et > *queryTimeout {
preloadTimer.Stop()
p.Close()
return nil, queryTimeoutError{et}
}
if err := p.PreloadRange(fp, offsetStart.Add(-rangeDuration), offsetEnd, *stalenessDelta); err != nil {
preloadTimer.Stop()
p.Close()
return nil, err
}
/*
if interval < rangeDuration {
if err := p.GetMetricRange(fp, offsetEnd, offsetEnd.Sub(offsetStart)+rangeDuration); err != nil {
p.Close()
return nil, err
}
} else {
if err := p.GetMetricRangeAtInterval(fp, offsetStart, offsetEnd, interval, rangeDuration); err != nil {
p.Close()
return nil, err
}
}
*/
}
for fp := range pt.instants {
if et := totalTimer.ElapsedTime(); et > *queryTimeout {
preloadTimer.Stop()
p.Close()
return nil, queryTimeoutError{et}
}
if err := p.PreloadRange(fp, offsetStart, offsetEnd, *stalenessDelta); err != nil {
preloadTimer.Stop()
p.Close()
return nil, err
}
}
}
preloadTimer.Stop()
ii := &iteratorInitializer{
storage: storage,
}
Walk(ii, node)
return p, nil
}