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engine.go
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engine.go
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package logql
import (
"context"
"errors"
"flag"
"fmt"
"sort"
"strconv"
"strings"
"time"
"github.com/opentracing/opentracing-go"
"github.com/grafana/loki/v3/pkg/logqlmodel/metadata"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/promql"
promql_parser "github.com/prometheus/prometheus/promql/parser"
"github.com/grafana/dskit/tenant"
"github.com/grafana/loki/v3/pkg/iter"
"github.com/grafana/loki/v3/pkg/logproto"
"github.com/grafana/loki/v3/pkg/logql/syntax"
"github.com/grafana/loki/v3/pkg/logqlmodel"
"github.com/grafana/loki/v3/pkg/logqlmodel/stats"
"github.com/grafana/loki/v3/pkg/util"
"github.com/grafana/loki/v3/pkg/util/constants"
"github.com/grafana/loki/v3/pkg/util/httpreq"
logutil "github.com/grafana/loki/v3/pkg/util/log"
"github.com/grafana/loki/v3/pkg/util/server"
"github.com/grafana/loki/v3/pkg/util/validation"
)
const (
DefaultBlockedQueryMessage = "blocked by policy"
)
var (
QueryTime = promauto.NewHistogramVec(prometheus.HistogramOpts{
Namespace: "logql",
Name: "query_duration_seconds",
Help: "LogQL query timings",
Buckets: prometheus.DefBuckets,
}, []string{"query_type"})
QueriesBlocked = promauto.NewCounterVec(prometheus.CounterOpts{
Namespace: constants.Loki,
Name: "blocked_queries",
Help: "Count of queries blocked by per-tenant policy",
}, []string{"user"})
lastEntryMinTime = time.Unix(-100, 0)
)
type QueryParams interface {
LogSelector() (syntax.LogSelectorExpr, error)
GetStart() time.Time
GetEnd() time.Time
GetShards() []string
}
// SelectParams specifies parameters passed to data selections.
type SelectLogParams struct {
*logproto.QueryRequest
}
func (s SelectLogParams) WithStoreChunks(chunkRefGroup *logproto.ChunkRefGroup) SelectLogParams {
cpy := *s.QueryRequest
cpy.StoreChunks = chunkRefGroup
return SelectLogParams{&cpy}
}
func (s SelectLogParams) String() string {
if s.QueryRequest != nil {
return fmt.Sprintf("selector=%s, direction=%s, start=%s, end=%s, limit=%d, shards=%s",
s.Selector, logproto.Direction_name[int32(s.Direction)], s.Start, s.End, s.Limit, strings.Join(s.Shards, ","))
}
return ""
}
// LogSelector returns the LogSelectorExpr from the SelectParams.
// The `LogSelectorExpr` can then returns all matchers and filters to use for that request.
func (s SelectLogParams) LogSelector() (syntax.LogSelectorExpr, error) {
if s.QueryRequest.Plan == nil {
return nil, errors.New("query plan is empty")
}
expr, ok := s.QueryRequest.Plan.AST.(syntax.LogSelectorExpr)
if !ok {
return nil, errors.New("only log selector is supported")
}
return expr, nil
}
type SelectSampleParams struct {
*logproto.SampleQueryRequest
}
func (s SelectSampleParams) WithStoreChunks(chunkRefGroup *logproto.ChunkRefGroup) SelectSampleParams {
cpy := *s.SampleQueryRequest
cpy.StoreChunks = chunkRefGroup
return SelectSampleParams{&cpy}
}
// Expr returns the SampleExpr from the SelectSampleParams.
// The `LogSelectorExpr` can then returns all matchers and filters to use for that request.
func (s SelectSampleParams) Expr() (syntax.SampleExpr, error) {
if s.SampleQueryRequest.Plan == nil {
return nil, errors.New("query plan is empty")
}
expr, ok := s.SampleQueryRequest.Plan.AST.(syntax.SampleExpr)
if !ok {
return nil, errors.New("only sample expression supported")
}
return expr, nil
}
// LogSelector returns the LogSelectorExpr from the SelectParams.
// The `LogSelectorExpr` can then returns all matchers and filters to use for that request.
func (s SelectSampleParams) LogSelector() (syntax.LogSelectorExpr, error) {
expr, err := s.Expr()
if err != nil {
return nil, err
}
return expr.Selector()
}
// Querier allows a LogQL expression to fetch an EntryIterator for a
// set of matchers and filters
type Querier interface {
SelectLogs(context.Context, SelectLogParams) (iter.EntryIterator, error)
SelectSamples(context.Context, SelectSampleParams) (iter.SampleIterator, error)
}
// EngineOpts is the list of options to use with the LogQL query engine.
type EngineOpts struct {
// MaxLookBackPeriod is the maximum amount of time to look back for log lines.
// only used for instant log queries.
MaxLookBackPeriod time.Duration `yaml:"max_look_back_period"`
// LogExecutingQuery will control if we log the query when Exec is called.
LogExecutingQuery bool `yaml:"-"`
}
func (opts *EngineOpts) RegisterFlagsWithPrefix(prefix string, f *flag.FlagSet) {
f.DurationVar(&opts.MaxLookBackPeriod, prefix+".engine.max-lookback-period", 30*time.Second, "The maximum amount of time to look back for log lines. Used only for instant log queries.")
// Log executing query by default
opts.LogExecutingQuery = true
}
func (opts *EngineOpts) applyDefault() {
if opts.MaxLookBackPeriod == 0 {
opts.MaxLookBackPeriod = 30 * time.Second
}
}
// Engine is the LogQL engine.
type Engine struct {
logger log.Logger
evaluatorFactory EvaluatorFactory
limits Limits
opts EngineOpts
}
// NewEngine creates a new LogQL Engine.
func NewEngine(opts EngineOpts, q Querier, l Limits, logger log.Logger) *Engine {
opts.applyDefault()
if logger == nil {
logger = log.NewNopLogger()
}
return &Engine{
logger: logger,
evaluatorFactory: NewDefaultEvaluator(q, opts.MaxLookBackPeriod),
limits: l,
opts: opts,
}
}
// Query creates a new LogQL query. Instant/Range type is derived from the parameters.
func (ng *Engine) Query(params Params) Query {
return &query{
logger: ng.logger,
params: params,
evaluator: ng.evaluatorFactory,
record: true,
logExecQuery: ng.opts.LogExecutingQuery,
limits: ng.limits,
}
}
// Query is a LogQL query to be executed.
type Query interface {
// Exec processes the query.
Exec(ctx context.Context) (logqlmodel.Result, error)
}
type query struct {
logger log.Logger
params Params
limits Limits
evaluator EvaluatorFactory
record bool
logExecQuery bool
}
func (q *query) resultLength(res promql_parser.Value) int {
switch r := res.(type) {
case promql.Vector:
return len(r)
case promql.Matrix:
return r.TotalSamples()
case logqlmodel.Streams:
return int(r.Lines())
case ProbabilisticQuantileMatrix:
return len(r)
default:
// for `scalar` or `string` or any other return type, we just return `0` as result length.
return 0
}
}
// Exec Implements `Query`. It handles instrumentation & defers to Eval.
func (q *query) Exec(ctx context.Context) (logqlmodel.Result, error) {
sp, ctx := opentracing.StartSpanFromContext(ctx, "query.Exec")
defer sp.Finish()
sp.LogKV(
"type", GetRangeType(q.params),
"query", q.params.QueryString(),
"start", q.params.Start(),
"end", q.params.End(),
"step", q.params.Step(),
"length", q.params.End().Sub(q.params.Start()),
)
if q.logExecQuery {
queryHash := util.HashedQuery(q.params.QueryString())
if GetRangeType(q.params) == InstantType {
level.Info(logutil.WithContext(ctx, q.logger)).Log("msg", "executing query", "type", "instant", "query", q.params.QueryString(), "query_hash", queryHash)
} else {
level.Info(logutil.WithContext(ctx, q.logger)).Log("msg", "executing query", "type", "range", "query", q.params.QueryString(), "length", q.params.End().Sub(q.params.Start()), "step", q.params.Step(), "query_hash", queryHash)
}
}
rangeType := GetRangeType(q.params)
timer := prometheus.NewTimer(QueryTime.WithLabelValues(string(rangeType)))
defer timer.ObserveDuration()
// records query statistics
start := time.Now()
statsCtx, ctx := stats.NewContext(ctx)
metadataCtx, ctx := metadata.NewContext(ctx)
data, err := q.Eval(ctx)
queueTime, _ := ctx.Value(httpreq.QueryQueueTimeHTTPHeader).(time.Duration)
statResult := statsCtx.Result(time.Since(start), queueTime, q.resultLength(data))
sp.LogKV(statResult.KVList()...)
status, _ := server.ClientHTTPStatusAndError(err)
if q.record {
RecordRangeAndInstantQueryMetrics(ctx, q.logger, q.params, strconv.Itoa(status), statResult, data)
}
return logqlmodel.Result{
Data: data,
Statistics: statResult,
Headers: metadataCtx.Headers(),
Warnings: metadataCtx.Warnings(),
}, err
}
func (q *query) Eval(ctx context.Context) (promql_parser.Value, error) {
tenants, _ := tenant.TenantIDs(ctx)
timeoutCapture := func(id string) time.Duration { return q.limits.QueryTimeout(ctx, id) }
queryTimeout := validation.SmallestPositiveNonZeroDurationPerTenant(tenants, timeoutCapture)
ctx, cancel := context.WithTimeout(ctx, queryTimeout)
defer cancel()
if q.checkBlocked(ctx, tenants) {
return nil, logqlmodel.ErrBlocked
}
switch e := q.params.GetExpression().(type) {
case syntax.SampleExpr:
value, err := q.evalSample(ctx, e)
return value, err
case syntax.LogSelectorExpr:
itr, err := q.evaluator.NewIterator(ctx, e, q.params)
if err != nil {
return nil, err
}
encodingFlags := httpreq.ExtractEncodingFlagsFromCtx(ctx)
if encodingFlags.Has(httpreq.FlagCategorizeLabels) {
itr = iter.NewCategorizeLabelsIterator(itr)
}
defer util.LogErrorWithContext(ctx, "closing iterator", itr.Close)
streams, err := readStreams(itr, q.params.Limit(), q.params.Direction(), q.params.Interval())
return streams, err
default:
return nil, fmt.Errorf("unexpected type (%T): cannot evaluate", e)
}
}
func (q *query) checkBlocked(ctx context.Context, tenants []string) bool {
blocker := newQueryBlocker(ctx, q)
for _, tenant := range tenants {
if blocker.isBlocked(ctx, tenant) {
QueriesBlocked.WithLabelValues(tenant).Inc()
return true
}
}
return false
}
// evalSample evaluate a sampleExpr
func (q *query) evalSample(ctx context.Context, expr syntax.SampleExpr) (promql_parser.Value, error) {
if lit, ok := expr.(*syntax.LiteralExpr); ok {
return q.evalLiteral(ctx, lit)
}
if vec, ok := expr.(*syntax.VectorExpr); ok {
return q.evalVector(ctx, vec)
}
tenantIDs, err := tenant.TenantIDs(ctx)
if err != nil {
return nil, err
}
maxIntervalCapture := func(id string) time.Duration { return q.limits.MaxQueryRange(ctx, id) }
maxQueryInterval := validation.SmallestPositiveNonZeroDurationPerTenant(tenantIDs, maxIntervalCapture)
if maxQueryInterval != 0 {
err = q.checkIntervalLimit(expr, maxQueryInterval)
if err != nil {
return nil, err
}
}
expr, err = optimizeSampleExpr(expr)
if err != nil {
return nil, err
}
stepEvaluator, err := q.evaluator.NewStepEvaluator(ctx, q.evaluator, expr, q.params)
if err != nil {
return nil, err
}
defer util.LogErrorWithContext(ctx, "closing SampleExpr", stepEvaluator.Close)
next, _, r := stepEvaluator.Next()
if stepEvaluator.Error() != nil {
return nil, stepEvaluator.Error()
}
if next && r != nil {
switch vec := r.(type) {
case SampleVector:
maxSeriesCapture := func(id string) int { return q.limits.MaxQuerySeries(ctx, id) }
maxSeries := validation.SmallestPositiveIntPerTenant(tenantIDs, maxSeriesCapture)
mfl := false
if rae, ok := expr.(*syntax.RangeAggregationExpr); ok && (rae.Operation == syntax.OpRangeTypeFirstWithTimestamp || rae.Operation == syntax.OpRangeTypeLastWithTimestamp) {
mfl = true
}
return q.JoinSampleVector(next, vec, stepEvaluator, maxSeries, mfl)
case ProbabilisticQuantileVector:
return MergeQuantileSketchVector(next, vec, stepEvaluator, q.params)
default:
return nil, fmt.Errorf("unsupported result type: %T", r)
}
}
return nil, errors.New("unexpected empty result")
}
func vectorsToSeries(vec promql.Vector, sm map[uint64]promql.Series) {
for _, p := range vec {
var (
series promql.Series
hash = p.Metric.Hash()
ok bool
)
series, ok = sm[hash]
if !ok {
series = promql.Series{
Metric: p.Metric,
Floats: make([]promql.FPoint, 0, 1),
}
sm[hash] = series
}
series.Floats = append(series.Floats, promql.FPoint{
T: p.T,
F: p.F,
})
sm[hash] = series
}
}
func (q *query) JoinSampleVector(next bool, r StepResult, stepEvaluator StepEvaluator, maxSeries int, mergeFirstLast bool) (promql_parser.Value, error) {
vec := promql.Vector{}
if next {
vec = r.SampleVector()
}
// fail fast for the first step or instant query
if len(vec) > maxSeries {
return nil, logqlmodel.NewSeriesLimitError(maxSeries)
}
seriesIndex := map[uint64]promql.Series{}
if GetRangeType(q.params) == InstantType {
// an instant query sharded first/last_over_time can return a single vector
if mergeFirstLast {
vectorsToSeries(vec, seriesIndex)
series := make([]promql.Series, 0, len(seriesIndex))
for _, s := range seriesIndex {
series = append(series, s)
}
result := promql.Matrix(series)
sort.Sort(result)
return result, stepEvaluator.Error()
}
sortByValue, err := Sortable(q.params)
if err != nil {
return nil, fmt.Errorf("fail to check Sortable, logql: %s ,err: %s", q.params.QueryString(), err)
}
if !sortByValue {
sort.Slice(vec, func(i, j int) bool { return labels.Compare(vec[i].Metric, vec[j].Metric) < 0 })
}
return vec, nil
}
for next {
vec = r.SampleVector()
vectorsToSeries(vec, seriesIndex)
// as we slowly build the full query for each steps, make sure we don't go over the limit of unique series.
if len(seriesIndex) > maxSeries {
return nil, logqlmodel.NewSeriesLimitError(maxSeries)
}
next, _, r = stepEvaluator.Next()
if stepEvaluator.Error() != nil {
return nil, stepEvaluator.Error()
}
}
series := make([]promql.Series, 0, len(seriesIndex))
for _, s := range seriesIndex {
series = append(series, s)
}
result := promql.Matrix(series)
sort.Sort(result)
return result, stepEvaluator.Error()
}
func (q *query) checkIntervalLimit(expr syntax.SampleExpr, limit time.Duration) error {
var err error
expr.Walk(func(e syntax.Expr) {
switch e := e.(type) {
case *syntax.RangeAggregationExpr:
if e.Left == nil || e.Left.Interval <= limit {
return
}
err = fmt.Errorf("%w: [%s] > [%s]", logqlmodel.ErrIntervalLimit, model.Duration(e.Left.Interval), model.Duration(limit))
}
})
return err
}
func (q *query) evalLiteral(_ context.Context, expr *syntax.LiteralExpr) (promql_parser.Value, error) {
value, err := expr.Value()
if err != nil {
return nil, err
}
s := promql.Scalar{
T: q.params.Start().UnixNano() / int64(time.Millisecond),
V: value,
}
if GetRangeType(q.params) == InstantType {
return s, nil
}
return PopulateMatrixFromScalar(s, q.params), nil
}
func (q *query) evalVector(_ context.Context, expr *syntax.VectorExpr) (promql_parser.Value, error) {
value, err := expr.Value()
if err != nil {
return nil, err
}
s := promql.Scalar{
T: q.params.Start().UnixNano() / int64(time.Millisecond),
V: value,
}
if GetRangeType(q.params) == InstantType {
return promql.Vector{promql.Sample{
T: q.params.Start().UnixMilli(),
F: value,
Metric: labels.Labels{},
}}, nil
}
return PopulateMatrixFromScalar(s, q.params), nil
}
func PopulateMatrixFromScalar(data promql.Scalar, params Params) promql.Matrix {
var (
start = params.Start()
end = params.End()
step = params.Step()
series = promql.Series{
Floats: make(
[]promql.FPoint,
0,
// allocate enough space for all needed entries
int(end.Sub(start)/step)+1,
),
}
)
for ts := start; !ts.After(end); ts = ts.Add(step) {
series.Floats = append(series.Floats, promql.FPoint{
T: ts.UnixNano() / int64(time.Millisecond),
F: data.V,
})
}
return promql.Matrix{series}
}
// readStreams reads the streams from the iterator and returns them sorted.
// If categorizeLabels is true, the stream labels contains just the stream labels and entries inside each stream have their
// structuredMetadata and parsed fields populated with structured metadata labels plus the parsed labels respectively.
// Otherwise, the stream labels are the whole series labels including the stream labels, structured metadata labels and parsed labels.
func readStreams(i iter.EntryIterator, size uint32, dir logproto.Direction, interval time.Duration) (logqlmodel.Streams, error) {
streams := map[string]*logproto.Stream{}
respSize := uint32(0)
// lastEntry should be a really old time so that the first comparison is always true, we use a negative
// value here because many unit tests start at time.Unix(0,0)
lastEntry := lastEntryMinTime
for respSize < size && i.Next() {
streamLabels, entry := i.Labels(), i.At()
forwardShouldOutput := dir == logproto.FORWARD &&
(entry.Timestamp.Equal(lastEntry.Add(interval)) || entry.Timestamp.After(lastEntry.Add(interval)))
backwardShouldOutput := dir == logproto.BACKWARD &&
(entry.Timestamp.Equal(lastEntry.Add(-interval)) || entry.Timestamp.Before(lastEntry.Add(-interval)))
// If step == 0 output every line.
// If lastEntry.Unix < 0 this is the first pass through the loop and we should output the line.
// Then check to see if the entry is equal to, or past a forward or reverse step
if interval == 0 || lastEntry.Unix() < 0 || forwardShouldOutput || backwardShouldOutput {
stream, ok := streams[streamLabels]
if !ok {
stream = &logproto.Stream{
Labels: streamLabels,
}
streams[streamLabels] = stream
}
stream.Entries = append(stream.Entries, entry)
lastEntry = i.At().Timestamp
respSize++
}
}
result := make(logqlmodel.Streams, 0, len(streams))
for _, stream := range streams {
result = append(result, *stream)
}
sort.Sort(result)
return result, i.Err()
}
type groupedAggregation struct {
labels labels.Labels
value float64
mean float64
groupCount int
heap vectorByValueHeap
reverseHeap vectorByReverseValueHeap
}