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label_names_and_values.go
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/
label_names_and_values.go
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// SPDX-License-Identifier: AGPL-3.0-only
package ingester
import (
"context"
"sync"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/tsdb"
"github.com/prometheus/prometheus/tsdb/index"
"go.uber.org/atomic"
"github.com/grafana/mimir/pkg/ingester/client"
)
const (
checkContextErrorSeriesCount = 1000 // series count interval in which context cancellation must be checked.
)
type labelValueCountResult struct {
val string
count uint64
err error
}
// labelNamesAndValues streams the messages with the labels and values of the labels matching the `matchers` param.
// Messages are immediately sent as soon they reach message size threshold defined in `messageSizeThreshold` param.
func labelNamesAndValues(
index tsdb.IndexReader,
matchers []*labels.Matcher,
messageSizeThreshold int,
stream client.Ingester_LabelNamesAndValuesServer,
filter func(name, value string) (bool, error),
) error {
ctx := stream.Context()
labelNames, err := index.LabelNames(ctx, matchers...)
if err != nil {
return err
}
response := client.LabelNamesAndValuesResponse{}
responseSizeBytes := 0
for _, labelName := range labelNames {
if err := ctx.Err(); err != nil {
return err
}
labelItem := &client.LabelValues{LabelName: labelName}
responseSizeBytes += len(labelName)
// send message if (response size + size of label name of current label) is greater or equals to threshold
if responseSizeBytes >= messageSizeThreshold {
err = client.SendLabelNamesAndValuesResponse(stream, &response)
if err != nil {
return err
}
response.Items = response.Items[:0]
responseSizeBytes = len(labelName)
}
values, err := index.LabelValues(ctx, labelName, matchers...)
if err != nil {
return err
}
filteredValues := values[:0]
for _, val := range values {
if ok, err := filter(labelName, val); err != nil {
return err
} else if ok {
// This append is safe because filteredValues is strictly smaller than values.
filteredValues = append(filteredValues, val)
}
}
values = filteredValues
lastAddedValueIndex := -1
for i, val := range values {
// sum up label values length until response size reached the threshold and after that add all values to the response
// starting from last sent value or from the first element and up to the current element (including).
responseSizeBytes += len(val)
if responseSizeBytes >= messageSizeThreshold {
labelItem.Values = values[lastAddedValueIndex+1 : i+1]
lastAddedValueIndex = i
response.Items = append(response.Items, labelItem)
err = client.SendLabelNamesAndValuesResponse(stream, &response)
if err != nil {
return err
}
// reset label values to reuse labelItem for the next values of current label.
labelItem.Values = labelItem.Values[:0]
response.Items = response.Items[:0]
if i+1 == len(values) {
// if it's the last value for this label then response size must be set to `0`
responseSizeBytes = 0
} else {
// if it is not the last value for this label then response size must be set to length of current label name.
responseSizeBytes = len(labelName)
}
} else if i+1 == len(values) {
// if response size does not reach the threshold, but it's the last label value then it must be added to labelItem
// and label item must be added to response.
labelItem.Values = values[lastAddedValueIndex+1 : i+1]
response.Items = append(response.Items, labelItem)
}
}
}
// send the last message if there is some data that was not sent.
if response.Size() > 0 {
return client.SendLabelNamesAndValuesResponse(stream, &response)
}
return nil
}
// labelValuesCardinality returns all values and series total count for label_names labels that match the matchers.
// Messages are immediately sent as soon they reach message size threshold.
func labelValuesCardinality(
lbNames []string,
matchers []*labels.Matcher,
idxReader tsdb.IndexReader,
postingsForMatchersFn func(context.Context, tsdb.IndexPostingsReader, ...*labels.Matcher) (index.Postings, error),
msgSizeThreshold int,
srv client.Ingester_LabelValuesCardinalityServer,
) error {
ctx := srv.Context()
resp := client.LabelValuesCardinalityResponse{}
respSize := 0
for _, lblName := range lbNames {
if err := ctx.Err(); err != nil {
return err
}
// Obtain all values for current label name.
lblValues, err := idxReader.LabelValues(ctx, lblName, matchers...)
if err != nil {
return err
}
// For each value count total number of series storing the result into cardinality response item.
var respItem *client.LabelValueSeriesCount
resultCh := computeLabelValuesSeriesCount(ctx, lblName, lblValues, matchers, idxReader, postingsForMatchersFn)
for countRes := range resultCh {
if countRes.err != nil {
return countRes.err
}
if countRes.count == 0 {
continue
}
if respItem == nil {
respItem = &client.LabelValueSeriesCount{
LabelName: lblName,
LabelValueSeries: make(map[string]uint64),
}
resp.Items = append(resp.Items, respItem)
}
respItem.LabelValueSeries[countRes.val] = countRes.count
respSize += len(countRes.val)
if respSize < msgSizeThreshold {
continue
}
// Flush the response when reached message threshold.
if err := client.SendLabelValuesCardinalityResponse(srv, &resp); err != nil {
return err
}
resp.Items = resp.Items[:0]
respSize = 0
respItem = nil
}
}
// Send response in case there are any pending items.
if len(resp.Items) > 0 {
return client.SendLabelValuesCardinalityResponse(srv, &resp)
}
return nil
}
func computeLabelValuesSeriesCount(
ctx context.Context,
lblName string,
lblValues []string,
matchers []*labels.Matcher,
idxReader tsdb.IndexReader,
postingsForMatchersFn func(context.Context, tsdb.IndexPostingsReader, ...*labels.Matcher) (index.Postings, error),
) <-chan labelValueCountResult {
maxConcurrency := 16
if len(lblValues) < maxConcurrency {
maxConcurrency = len(lblValues)
}
wg := sync.WaitGroup{}
wg.Add(len(lblValues))
countCh := make(chan labelValueCountResult, len(lblValues))
indexes := atomic.NewInt64(-1)
for ix := 0; ix < maxConcurrency; ix++ {
go func() {
for {
idx := int(indexes.Inc())
if idx >= len(lblValues) {
return
}
seriesCount, err := countLabelValueSeries(ctx, lblName, lblValues[idx], matchers, idxReader, postingsForMatchersFn)
countCh <- labelValueCountResult{
val: lblValues[idx],
count: seriesCount,
err: err,
}
wg.Done()
}
}()
}
go func() {
wg.Wait()
close(countCh)
}()
return countCh
}
func countLabelValueSeries(
ctx context.Context,
lblName string,
lblValue string,
matchers []*labels.Matcher,
idxReader tsdb.IndexReader,
postingsForMatchersFn func(context.Context, tsdb.IndexPostingsReader, ...*labels.Matcher) (index.Postings, error),
) (uint64, error) {
if err := ctx.Err(); err != nil {
return 0, err
}
var count uint64
// We will use original matchers + one extra matcher for label value.
lblValMatchers := make([]*labels.Matcher, len(matchers)+1)
copy(lblValMatchers, matchers)
lblValMatchers[len(lblValMatchers)-1] = labels.MustNewMatcher(labels.MatchEqual, lblName, lblValue)
p, err := postingsForMatchersFn(ctx, idxReader, lblValMatchers...)
if err != nil {
return 0, err
}
for p.Next() {
count++
if count%checkContextErrorSeriesCount == 0 {
if err := ctx.Err(); err != nil {
return 0, err
}
}
}
if p.Err() != nil {
return 0, p.Err()
}
return count, nil
}