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perf(blooms): Avoid tiny string allocations for insert cache #13487

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Jul 11, 2024
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perf(blooms): Avoid tiny string allocations for insert cache #13487

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10 changes: 7 additions & 3 deletions pkg/storage/bloom/v1/bloom_tokenizer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package v1

import (
"math"
"unsafe"

"github.com/go-kit/log/level"

Expand Down Expand Up @@ -216,10 +217,12 @@ outer:
for itr.Next() {
tok := itr.At()
tokens++

// TODO[owen-d]: [n]byte this
str := string(tok)
_, found := bt.cache[str] // A cache is used ahead of the SBF, as it cuts out the costly operations of scaling bloom filters
if found {
// To avoid allocations, an unsafe string can be used to check ownership in cache.
str := unsafe.String(unsafe.SliceData(tok), len(tok))
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note: The []byte is reused across Next calls. I wonder if this impacts us here.

// The Token iterator uses shared buffers for performance. The []byte returned by At()
// is not safe for use after subsequent calls to Next()

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The unsafe string is only used for the membership check, not the assignment in the map.

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Oh good point. LGTM

// A cache is used ahead of the SBF, as it cuts out the costly operations of scaling bloom filters
if _, found := bt.cache[str]; found {
cachedInserts++
continue
}
Expand All @@ -246,6 +249,7 @@ outer:

// only register the key in the cache if it was successfully added to the bloom
// as can prevent us from trying subsequent copies
str = string(tok)
bt.cache[str] = nil
if len(bt.cache) >= cacheSize { // While crude, this has proven efficient in performance testing. This speaks to the similarity in log lines near each other
clear(bt.cache)
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