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textparse: Fix endless loop #12731

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PR #12557 introduced the possibility of parsing multiple exemplars per
native histograms. It did so by requiring the `Exemplar` method of the
parser to be called repeatedly until it returns false. However, the
protobuf parser code wasn't correctly updated for the old case of a
single exemplar for a classic bucket (if actually parsed as a classic
bucket) and a single exemplar on a counter. In those cases, the method
would return `true` forever, yielding the same exemplar again and
again, leading to an endless loop.

With this fix, the state is now tracked and the single exemplar is
only returned once.

Signed-off-by: beorn7 <beorn@grafana.com>
This commit is contained in:
beorn7 2023-08-22 21:03:54 +02:00
parent 3d9a830f2f
commit 65ccf4460a
1 changed files with 10 additions and 0 deletions
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10
model/textparse/protobufparse.go
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@ -56,6 +56,10 @@ type ProtobufParser struct {
fieldsDone bool // true if no more fields of a Summary or (legacy) Histogram to be processed.
redoClassic bool // true after parsing a native histogram if we need to parse it again as a classic histogram.
// exemplarReturned is set to true each time an exemplar has been
// returned, and set back to false upon each Next() call.
exemplarReturned bool
// state is marked by the entry we are processing. EntryInvalid implies
// that we have to decode the next MetricFamily.
state Entry
@ -295,6 +299,10 @@ func (p *ProtobufParser) Metric(l *labels.Labels) string {
// histogram, the legacy bucket section is still used for exemplars. To ingest
// all exemplars, call the Exemplar method repeatedly until it returns false.
func (p *ProtobufParser) Exemplar(ex *exemplar.Exemplar) bool {
if p.exemplarReturned && p.state == EntrySeries {
// We only ever return one exemplar per (non-native-histogram) series.
return false
}
m := p.mf.GetMetric()[p.metricPos]
var exProto *dto.Exemplar
switch p.mf.GetType() {
@ -335,6 +343,7 @@ func (p *ProtobufParser) Exemplar(ex *exemplar.Exemplar) bool {
}
p.builder.Sort()
ex.Labels = p.builder.Labels()
p.exemplarReturned = true
return true
}
@ -342,6 +351,7 @@ func (p *ProtobufParser) Exemplar(ex *exemplar.Exemplar) bool {
// text format parser). It returns (EntryInvalid, io.EOF) if no samples were
// read.
func (p *ProtobufParser) Next() (Entry, error) {
p.exemplarReturned = false
switch p.state {
case EntryInvalid:
p.metricPos = 0