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chore: reduce string allocations in TSI series cache (#27255) #27257

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Merged
davidby-influx merged 1 commit into from
Feb 27, 2026
Merged

chore: reduce string allocations in TSI series cache (#27255) #27257

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37 changes: 21 additions & 16 deletions tsdb/index/tsi1/cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -56,11 +56,11 @@ func (c *TagValueSeriesIDCache) get(name, key, value []byte) *tsdb.SeriesIDSet {
return nil
}

// exists returns true if the an item exists for the tuple {name, key, value}.
func (c *TagValueSeriesIDCache) exists(name, key, value []byte) bool {
if mmap, ok := c.cache[string(name)]; ok {
if tkmap, ok := mmap[string(key)]; ok {
_, ok := tkmap[string(value)]
// exists returns true if the item exists for the tuple {name, key, value}.
func (c *TagValueSeriesIDCache) exists(name, key, value string) bool {
if mmap, ok := c.cache[name]; ok {
if tkmap, ok := mmap[key]; ok {
_, ok := tkmap[value]
return ok
}
}
Expand Down Expand Up @@ -97,8 +97,13 @@ func (c *TagValueSeriesIDCache) measurementContainsSets(name []byte) bool {
// the cache is at its limit, then the least recently used item is evicted.
func (c *TagValueSeriesIDCache) Put(name, key, value []byte, ss *tsdb.SeriesIDSet) {
c.Lock()
// Convert once; the same string backing array is shared between
// the cache element (used during eviction) and the map keys.
nameStr := string(name)
keyStr := string(key)
valueStr := string(value)
// Check under the write lock if the relevant item is now in the cache.
if c.exists(name, key, value) {
if c.exists(nameStr, keyStr, valueStr) {
c.Unlock()
return
}
Expand All @@ -111,32 +116,32 @@ func (c *TagValueSeriesIDCache) Put(name, key, value []byte, ss *tsdb.SeriesIDSe

// Create list item, and add to the front of the eviction list.
listElement := c.evictor.PushFront(&seriesIDCacheElement{
name: string(name),
key: string(key),
value: string(value),
name: nameStr,
key: keyStr,
value: valueStr,
SeriesIDSet: ss,
})

// Add the listElement to the set of items.
if mmap, ok := c.cache[string(name)]; ok {
if tkmap, ok := mmap[string(key)]; ok {
if _, ok := tkmap[string(value)]; ok {
if mmap, ok := c.cache[nameStr]; ok {
if tkmap, ok := mmap[keyStr]; ok {
if _, ok := tkmap[valueStr]; ok {
goto EVICT
}

// Add the set to the map
tkmap[string(value)] = listElement
tkmap[valueStr] = listElement
goto EVICT
}

// No series set map for the tag key - first tag value for the tag key.
mmap[string(key)] = map[string]*list.Element{string(value): listElement}
mmap[keyStr] = map[string]*list.Element{valueStr: listElement}
goto EVICT
}

// No map for the measurement - first tag key for the measurment.
c.cache[string(name)] = map[string]map[string]*list.Element{
string(key): map[string]*list.Element{string(value): listElement},
c.cache[nameStr] = map[string]map[string]*list.Element{
keyStr: map[string]*list.Element{valueStr: listElement},
}

EVICT:
Expand Down