Like Prometheus, but for logs.
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loki/pkg/dataobj/logs_reader.go

446 lines
12 KiB

package dataobj
import (
"cmp"
"context"
"errors"
"fmt"
"io"
"iter"
"maps"
"sort"
"strconv"
"time"
"unsafe"
"github.com/prometheus/prometheus/model/labels"
"github.com/grafana/loki/pkg/push"
"github.com/grafana/loki/v3/pkg/dataobj/internal/dataset"
"github.com/grafana/loki/v3/pkg/dataobj/internal/encoding"
"github.com/grafana/loki/v3/pkg/dataobj/internal/metadata/datasetmd"
"github.com/grafana/loki/v3/pkg/dataobj/internal/metadata/filemd"
"github.com/grafana/loki/v3/pkg/dataobj/internal/metadata/logsmd"
"github.com/grafana/loki/v3/pkg/dataobj/internal/result"
"github.com/grafana/loki/v3/pkg/dataobj/internal/sections/logs"
"github.com/grafana/loki/v3/pkg/dataobj/internal/util/slicegrow"
"github.com/grafana/loki/v3/pkg/dataobj/internal/util/symbolizer"
)
// A Record is an individual log record in a data object.
type Record struct {
StreamID int64 // StreamID associated with the log record.
Timestamp time.Time // Timestamp of the log record.
Metadata labels.Labels // Set of metadata associated with the log record.
Line []byte // Line of the log record.
}
// LogsReader reads the set of logs from an [Object].
type LogsReader struct {
obj *Object
idx int
ready bool
matchIDs map[int64]struct{}
predicate LogsPredicate
buf []dataset.Row
record logs.Record
reader *dataset.Reader
columns []dataset.Column
columnDesc []*logsmd.ColumnDesc
symbols *symbolizer.Symbolizer
}
// NewLogsReader creates a new LogsReader that reads from the logs section of
// the given object.
func NewLogsReader(obj *Object, sectionIndex int) *LogsReader {
var lr LogsReader
lr.Reset(obj, sectionIndex)
return &lr
}
// MatchStreams provides a sequence of stream IDs for the logs reader to match.
// [LogsReader.Read] will only return logs for the provided stream IDs.
//
// MatchStreams may be called multiple times to match multiple sets of streams.
//
// MatchStreams may only be called before reading begins or after a call to
// [LogsReader.Reset].
func (r *LogsReader) MatchStreams(ids iter.Seq[int64]) error {
if r.ready {
return fmt.Errorf("cannot change matched streams after reading has started")
}
if r.matchIDs == nil {
r.matchIDs = make(map[int64]struct{})
}
for id := range ids {
r.matchIDs[id] = struct{}{}
}
return nil
}
// SetPredicate sets the predicate to use for filtering logs. [LogsReader.Read]
// will only return logs for which the predicate passes.
//
// A predicate may only be set before reading begins or after a call to
// [LogsReader.Reset].
func (r *LogsReader) SetPredicate(p LogsPredicate) error {
if r.ready {
return fmt.Errorf("cannot change predicate after reading has started")
}
r.predicate = p
return nil
}
// Read reads up to the next len(s) records from the reader and stores them
// into s. It returns the number of records read and any error encountered. At
// the end of the logs section, Read returns 0, io.EOF.
func (r *LogsReader) Read(ctx context.Context, s []Record) (int, error) {
if r.obj == nil {
return 0, io.EOF
} else if r.idx < 0 {
return 0, fmt.Errorf("invalid section index %d", r.idx)
}
if !r.ready {
err := r.initReader(ctx)
if err != nil {
return 0, err
}
}
r.buf = slicegrow.GrowToCap(r.buf, len(s))
r.buf = r.buf[:len(s)]
n, err := r.reader.Read(ctx, r.buf)
if err != nil && !errors.Is(err, io.EOF) {
return 0, fmt.Errorf("reading rows: %w", err)
} else if n == 0 && errors.Is(err, io.EOF) {
return 0, io.EOF
}
for i := range r.buf[:n] {
err := logs.Decode(r.columnDesc, r.buf[i], &r.record)
if err != nil {
return i, fmt.Errorf("decoding record: %w", err)
}
// Copy record data into pre-allocated output buffer
s[i].StreamID = r.record.StreamID
s[i].Timestamp = r.record.Timestamp
s[i].Metadata = slicegrow.GrowToCap(s[i].Metadata, len(r.record.Metadata))
s[i].Metadata = s[i].Metadata[:len(r.record.Metadata)]
for j := range r.record.Metadata {
s[i].Metadata[j].Name = r.symbols.Get(r.record.Metadata[j].Name)
s[i].Metadata[j].Value = r.symbols.Get(unsafeString(r.record.Metadata[j].Value))
}
s[i].Line = slicegrow.Copy(s[i].Line, r.record.Line)
}
return n, nil
}
func unsafeSlice(data string, capacity int) []byte {
if capacity <= 0 {
capacity = len(data)
}
return unsafe.Slice(unsafe.StringData(data), capacity)
}
func unsafeString(data []byte) string {
return unsafe.String(unsafe.SliceData(data), len(data))
}
func (r *LogsReader) initReader(ctx context.Context) error {
dec := r.obj.dec.LogsDecoder()
sec, err := r.findSection(ctx)
if err != nil {
return fmt.Errorf("finding section: %w", err)
}
columnDescs, err := dec.Columns(ctx, sec)
if err != nil {
return fmt.Errorf("reading columns: %w", err)
}
dset := encoding.LogsDataset(dec, sec)
columns, err := result.Collect(dset.ListColumns(ctx))
if err != nil {
return fmt.Errorf("reading columns: %w", err)
}
// r.predicate doesn't contain mappings of stream IDs; we need to build
// that as a separate predicate and AND them together.
predicate := streamIDPredicate(maps.Keys(r.matchIDs), columns, columnDescs)
if r.predicate != nil {
predicate = dataset.AndPredicate{
Left: predicate,
Right: translateLogsPredicate(r.predicate, columns, columnDescs),
}
}
readerOpts := dataset.ReaderOptions{
Dataset: dset,
Columns: columns,
Predicate: predicate,
TargetCacheSize: 16_000_000, // Permit up to 16MB of cache pages.
}
if r.reader == nil {
r.reader = dataset.NewReader(readerOpts)
} else {
r.reader.Reset(readerOpts)
}
if r.symbols == nil {
r.symbols = symbolizer.New(128, 100_000)
} else {
r.symbols.Reset()
}
r.columnDesc = columnDescs
r.columns = columns
r.ready = true
return nil
}
func (r *LogsReader) findSection(ctx context.Context) (*filemd.SectionInfo, error) {
si, err := r.obj.dec.Sections(ctx)
if err != nil {
return nil, fmt.Errorf("reading sections: %w", err)
}
var n int
for _, s := range si {
if s.Type == filemd.SECTION_TYPE_LOGS {
if n == r.idx {
return s, nil
}
n++
}
}
return nil, fmt.Errorf("section index %d not found", r.idx)
}
func convertMetadata(md push.LabelsAdapter) []logs.RecordMetadata {
l := make([]logs.RecordMetadata, 0, len(md))
for _, label := range md {
l = append(l, logs.RecordMetadata{Name: label.Name, Value: unsafeSlice(label.Value, 0)})
}
sort.Slice(l, func(i, j int) bool {
if l[i].Name == l[j].Name {
return cmp.Compare(unsafeString(l[i].Value), unsafeString(l[j].Value)) < 0
}
return cmp.Compare(l[i].Name, l[j].Name) < 0
})
return l
}
// Reset resets the LogsReader with a new object and section index to read
// from. Reset allows reusing a LogsReader without allocating a new one.
//
// Any set predicate is cleared when Reset is called.
//
// Reset may be called with a nil object and a negative section index to clear
// the LogsReader without needing a new object.
func (r *LogsReader) Reset(obj *Object, sectionIndex int) {
r.obj = obj
r.idx = sectionIndex
r.ready = false
clear(r.matchIDs)
r.predicate = nil
r.columns = nil
r.columnDesc = nil
if r.symbols != nil {
r.symbols.Reset()
}
// We leave r.reader as-is to avoid reallocating; it'll be reset on the first
// call to Read.
}
// Close closes the LogsReader and releases any resources it holds. Closed
// LogsReaders can be reused by calling [LogsReader.Reset].
func (r *LogsReader) Close() error {
if r.reader != nil {
return r.reader.Close()
}
return nil
}
func streamIDPredicate(ids iter.Seq[int64], columns []dataset.Column, columnDesc []*logsmd.ColumnDesc) dataset.Predicate {
streamIDColumn := findColumnFromDesc(columns, columnDesc, func(desc *logsmd.ColumnDesc) bool {
return desc.Type == logsmd.COLUMN_TYPE_STREAM_ID
})
if streamIDColumn == nil {
return dataset.FalsePredicate{}
}
var values []dataset.Value
for id := range ids {
values = append(values, dataset.Int64Value(id))
}
if len(values) == 0 {
return nil
}
return dataset.InPredicate{
Column: streamIDColumn,
Values: values,
}
}
func translateLogsPredicate(p LogsPredicate, columns []dataset.Column, columnDesc []*logsmd.ColumnDesc) dataset.Predicate {
if p == nil {
return nil
}
switch p := p.(type) {
case AndPredicate[LogsPredicate]:
return dataset.AndPredicate{
Left: translateLogsPredicate(p.Left, columns, columnDesc),
Right: translateLogsPredicate(p.Right, columns, columnDesc),
}
case OrPredicate[LogsPredicate]:
return dataset.OrPredicate{
Left: translateLogsPredicate(p.Left, columns, columnDesc),
Right: translateLogsPredicate(p.Right, columns, columnDesc),
}
case NotPredicate[LogsPredicate]:
return dataset.NotPredicate{
Inner: translateLogsPredicate(p.Inner, columns, columnDesc),
}
case TimeRangePredicate[LogsPredicate]:
timeColumn := findColumnFromDesc(columns, columnDesc, func(desc *logsmd.ColumnDesc) bool {
return desc.Type == logsmd.COLUMN_TYPE_TIMESTAMP
})
if timeColumn == nil {
return dataset.FalsePredicate{}
}
return convertLogsTimePredicate(p, timeColumn)
case LogMessageFilterPredicate:
messageColumn := findColumnFromDesc(columns, columnDesc, func(desc *logsmd.ColumnDesc) bool {
return desc.Type == logsmd.COLUMN_TYPE_MESSAGE
})
if messageColumn == nil {
return dataset.FalsePredicate{}
}
return dataset.FuncPredicate{
Column: messageColumn,
Keep: func(_ dataset.Column, value dataset.Value) bool {
if value.Type() == datasetmd.VALUE_TYPE_BYTE_ARRAY {
// To handle older dataobjs that still use string type for message column. This can be removed in future.
return p.Keep(value.ByteArray())
}
return p.Keep(value.ByteArray())
},
}
case MetadataMatcherPredicate:
metadataColumn := findColumnFromDesc(columns, columnDesc, func(desc *logsmd.ColumnDesc) bool {
return desc.Type == logsmd.COLUMN_TYPE_METADATA && desc.Info.Name == p.Key
})
if metadataColumn == nil {
return dataset.FalsePredicate{}
}
return dataset.EqualPredicate{
Column: metadataColumn,
Value: dataset.ByteArrayValue(unsafeSlice(p.Value, 0)),
}
case MetadataFilterPredicate:
metadataColumn := findColumnFromDesc(columns, columnDesc, func(desc *logsmd.ColumnDesc) bool {
return desc.Type == logsmd.COLUMN_TYPE_METADATA && desc.Info.Name == p.Key
})
if metadataColumn == nil {
return dataset.FalsePredicate{}
}
return dataset.FuncPredicate{
Column: metadataColumn,
Keep: func(_ dataset.Column, value dataset.Value) bool {
return p.Keep(p.Key, valueToString(value))
},
}
default:
panic(fmt.Sprintf("unsupported predicate type %T", p))
}
}
func convertLogsTimePredicate(p TimeRangePredicate[LogsPredicate], column dataset.Column) dataset.Predicate {
var start dataset.Predicate = dataset.GreaterThanPredicate{
Column: column,
Value: dataset.Int64Value(p.StartTime.UnixNano()),
}
if p.IncludeStart {
start = dataset.OrPredicate{
Left: start,
Right: dataset.EqualPredicate{
Column: column,
Value: dataset.Int64Value(p.StartTime.UnixNano()),
},
}
}
var end dataset.Predicate = dataset.LessThanPredicate{
Column: column,
Value: dataset.Int64Value(p.EndTime.UnixNano()),
}
if p.IncludeEnd {
end = dataset.OrPredicate{
Left: end,
Right: dataset.EqualPredicate{
Column: column,
Value: dataset.Int64Value(p.EndTime.UnixNano()),
},
}
}
return dataset.AndPredicate{
Left: start,
Right: end,
}
}
func findColumnFromDesc[Desc any](columns []dataset.Column, descs []Desc, check func(Desc) bool) dataset.Column {
for i, desc := range descs {
if check(desc) {
return columns[i]
}
}
return nil
}
func valueToString(value dataset.Value) string {
switch value.Type() {
case datasetmd.VALUE_TYPE_UNSPECIFIED:
return ""
case datasetmd.VALUE_TYPE_INT64:
return strconv.FormatInt(value.Int64(), 10)
case datasetmd.VALUE_TYPE_UINT64:
return strconv.FormatUint(value.Uint64(), 10)
case datasetmd.VALUE_TYPE_BYTE_ARRAY:
return unsafeString(value.ByteArray())
default:
panic(fmt.Sprintf("unsupported value type %s", value.Type()))
}
}