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scrape: reorder the switch case of errors (#15991)

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Change case order for switch scrapeLoop

This commit changes the ordering in error identification switch cases for better production performance and adds reasonings behind error switch case order as comments.

---------

Signed-off-by: Laimis Juzeliūnas <asnelaimis@gmail.com>
This commit is contained in:
Laimis Juzeliūnas 2025-02-13 15:25:50 +02:00 committed by GitHub
parent e936e419b0
commit a5ffa83be8
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1 changed files with 16 additions and 12 deletions
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28
scrape/scrape.go
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@ -1962,12 +1962,24 @@ func isSeriesPartOfFamily(mName string, mfName []byte, typ model.MetricType) boo
// Adds samples to the appender, checking the error, and then returns the # of samples added,
// whether the caller should continue to process more samples, and any sample or bucket limit errors.
// Switch error cases for Sample and Bucket limits are checked first since they're more common
// during normal operation (e.g., accidental cardinality explosion, sudden traffic spikes).
// Current case ordering prevents exercising other cases when limits are exceeded.
// Remaining error cases typically occur only a few times, often during initial setup.
func (sl *scrapeLoop) checkAddError(met []byte, err error, sampleLimitErr, bucketLimitErr *error, appErrs *appendErrors) (bool, error) {
switch {
case err == nil:
return true, nil
case errors.Is(err, storage.ErrNotFound):
return false, storage.ErrNotFound
case errors.Is(err, errSampleLimit):
// Keep on parsing output if we hit the limit, so we report the correct
// total number of samples scraped.
*sampleLimitErr = err
return false, nil
case errors.Is(err, errBucketLimit):
// Keep on parsing output if we hit the limit, so we report the bucket
// total number of samples scraped.
*bucketLimitErr = err
return false, nil
case errors.Is(err, storage.ErrOutOfOrderSample):
appErrs.numOutOfOrder++
sl.l.Debug("Out of order sample", "series", string(met))
@ -1983,16 +1995,8 @@ func (sl *scrapeLoop) checkAddError(met []byte, err error, sampleLimitErr, bucke
sl.l.Debug("Out of bounds metric", "series", string(met))
sl.metrics.targetScrapeSampleOutOfBounds.Inc()
return false, nil
case errors.Is(err, errSampleLimit):
// Keep on parsing output if we hit the limit, so we report the correct
// total number of samples scraped.
*sampleLimitErr = err
return false, nil
case errors.Is(err, errBucketLimit):
// Keep on parsing output if we hit the limit, so we report the correct
// total number of samples scraped.
*bucketLimitErr = err
return false, nil
case errors.Is(err, storage.ErrNotFound):
return false, storage.ErrNotFound
default:
return false, err
}