tsdb [PERF]: move lastHistogramValue/lastFloatHistogramValue from memSeries to appenders#18515
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tsdb [PERF]: move lastHistogramValue/lastFloatHistogramValue from memSeries to appenders#18515
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…to appenders Store the last appended histogram and float histogram in the HistogramAppender and FloatHistogramAppender respectively, instead of keeping redundant pointers in memSeries. HistogramAppender gains LastHistogram()/SetLastHistogram() and FloatHistogramAppender gains LastFloatHistogram()/SetLastFloatHistogram(). All callers in head_append.go, head.go, head_read.go and head_wal.go are updated to type-assert on series.app and call the new accessors. The chunkSnapshotRecord fields are left unchanged (WAL on-disk format must not change); snapshot load now initialises the appender from the snapshot record via the new setters. Co-Authored-By: Claude Sonnet 4.6 <[email protected]> Signed-off-by: György Krajcsovits <[email protected]>
…astValue into appenders Add two methods to the chunkenc.Appender interface: - IsStaleLastValue() bool — replaces per-type stale checks scattered across head.go, head_read.go, head_append.go and head_wal.go. - IsEqual(v float64, h *histogram.Histogram, fh *histogram.FloatHistogram) bool — replaces type assertions in appendableHistogram and appendableFloatHistogram. xorAppender and xor2Appender implement IsStaleLastValue using the existing a.v field (the last appended float), making it the canonical storage for the last float value within the appender. HistogramAppender and FloatHistogramAppender use their existing lastValue fields. All callers are updated: the five separate stale checks in head.go, head_read.go, head_append.go and head_wal.go collapse to isStaleLastValue() calls; the duplicate-detection type assertions in appendableHistogram and appendableFloatHistogram are replaced with IsEqual; and stale-transition tracking in commitHistograms, commitFloatHistograms and WAL replay becomes a single IsStaleLastValue() call per block. The isHistogramStale helper is removed. Co-Authored-By: Claude Sonnet 4.6 <[email protected]> Signed-off-by: György Krajcsovits <[email protected]>
…ppender; remove memSeries.lastValue Replace the two helper methods IsStaleLastValue() and IsEqual() on the chunkenc.Appender interface with a single LastValue() method that returns (v float64, h *histogram.Histogram, fh *histogram.FloatHistogram). This lets callers inspect the last appended value without a type switch and without maintaining a separate copy of the last float value in memSeries. The field s.lastValue float64 is removed from memSeries as a result. Co-Authored-By: Claude Sonnet 4.6 <[email protected]> Signed-off-by: György Krajcsovits <[email protected]>
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Summary
lastHistogramValue *histogram.HistogramandlastFloatHistogramValue *histogram.FloatHistogramfrommemSeries, reducing its size by two pointer fields (16 bytes on 64-bit).lastValuetoHistogramAppenderandFloatHistogramAppender(set on everyappendHistogram/appendFloatHistogramcall), withLastHistogram()/SetLastHistogram()andLastFloatHistogram()/SetLastFloatHistogram()accessors.series.app; a newisHistogramStale()helper onmemSeriesde-duplicates the four stale-check locations.chunkSnapshotRecordWAL format is unchanged; snapshot load now restores appender state via the new setters.Signed-off-by: György Krajcsovits [email protected]
Coded with Claude Sonnet 4.6.