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f3e5c9c246
Previously only up to 100K results were cached. This could result in sub-optimal performance when more than 100K unique strings were actually used. For example, when the relabeling rule was applied to a million of unique Graphite metric names like in the https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3466 This commit should reduce the long-term CPU usage for https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3466 after all the unique Graphite metrics are registered in the FastStringMatcher.Transform() cache. It is expected that the number of unique strings, which are passed to FastStringMatcher.Match(), FastStringTransformer.Transform() and to InternString() during the last 5 minutes, is limited, so the function results fit memory. Otherwise OOM crash can occur. This should be the case for typical production workloads.
81 lines
2.2 KiB
Go
81 lines
2.2 KiB
Go
package bytesutil
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import (
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"strings"
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"sync"
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"sync/atomic"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
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)
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// FastStringMatcher implements fast matcher for strings.
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//
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// It caches string match results and returns them back on the next calls
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// without calling the matchFunc, which may be expensive.
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type FastStringMatcher struct {
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lastCleanupTime uint64
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m sync.Map
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matchFunc func(s string) bool
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}
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type fsmEntry struct {
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lastAccessTime uint64
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ok bool
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}
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// NewFastStringMatcher creates new matcher, which applies matchFunc to strings passed to Match()
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//
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// matchFunc must return the same result for the same input.
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func NewFastStringMatcher(matchFunc func(s string) bool) *FastStringMatcher {
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return &FastStringMatcher{
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lastCleanupTime: fasttime.UnixTimestamp(),
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matchFunc: matchFunc,
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}
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}
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// Match applies matchFunc to s and returns the result.
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func (fsm *FastStringMatcher) Match(s string) bool {
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ct := fasttime.UnixTimestamp()
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v, ok := fsm.m.Load(s)
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if ok {
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// Fast path - s match result is found in the cache.
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e := v.(*fsmEntry)
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if atomic.LoadUint64(&e.lastAccessTime)+10 < ct {
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// Reduce the frequency of e.lastAccessTime update to once per 10 seconds
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// in order to improve the fast path speed on systems with many CPU cores.
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atomic.StoreUint64(&e.lastAccessTime, ct)
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}
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return e.ok
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}
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// Slow path - run matchFunc for s and store the result in the cache.
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b := fsm.matchFunc(s)
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e := &fsmEntry{
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lastAccessTime: ct,
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ok: b,
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}
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// Make a copy of s in order to limit memory usage to the s length,
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// since the s may point to bigger string.
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// This also protects from the case when s contains unsafe string, which points to a temporary byte slice.
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// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3227
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s = strings.Clone(s)
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fsm.m.Store(s, e)
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if atomic.LoadUint64(&fsm.lastCleanupTime)+61 < ct {
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// Perform a global cleanup for fsm.m by removing items, which weren't accessed
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// during the last 5 minutes.
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atomic.StoreUint64(&fsm.lastCleanupTime, ct)
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m := &fsm.m
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m.Range(func(k, v interface{}) bool {
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e := v.(*fsmEntry)
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if atomic.LoadUint64(&e.lastAccessTime)+5*60 < ct {
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m.Delete(k)
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}
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return true
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})
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}
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return b
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}
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