Reduce allocations in isMatch in filestore/memstore (#5573)

Otherwise long subjects could cause us to make the same reallocations on each call to `tokenizeSubjectIntoSlice` without reusing the newly sized underlying array for the next call. Signed-off-by: Neil Twigg <[email protected]>
nats-io · Jun 21, 2024 · 9c3b5d4 · 9c3b5d4
2 parents 2f364d9 + 2fc700c
commit 9c3b5d4
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Showing 2 changed files with 24 additions and 24 deletions.
diff --git a/server/filestore.go b/server/filestore.go
@@ -2325,16 +2325,15 @@ func (mb *msgBlock) firstMatching(filter string, wc bool, start uint64, sm *Stor
 	lseq := atomic.LoadUint64(&mb.last.seq)
 
 	// Optionally build the isMatch for wildcard filters.
-	tsa := [32]string{}
-	fsa := [32]string{}
-	var fts []string
+	_tsa, _fsa := [32]string{}, [32]string{}
+	tsa, fsa := _tsa[:0], _fsa[:0]
 	var isMatch func(subj string) bool
 	// Decide to build.
 	if wc {
-		fts = tokenizeSubjectIntoSlice(fsa[:0], filter)
+		fsa = tokenizeSubjectIntoSlice(fsa[:0], filter)
 		isMatch = func(subj string) bool {
-			tts := tokenizeSubjectIntoSlice(tsa[:0], subj)
-			return isSubsetMatchTokenized(tts, fts)
+			tsa = tokenizeSubjectIntoSlice(tsa[:0], subj)
+			return isSubsetMatchTokenized(tsa, fsa)
 		}
 	}
 
@@ -2469,9 +2468,9 @@ func (mb *msgBlock) filteredPendingLocked(filter string, wc bool, sseq uint64) (
 	// Make sure we have fss loaded.
 	mb.ensurePerSubjectInfoLoaded()
 
-	tsa := [32]string{}
-	fsa := [32]string{}
-	fts := tokenizeSubjectIntoSlice(fsa[:0], filter)
+	_tsa, _fsa := [32]string{}, [32]string{}
+	tsa, fsa := _tsa[:0], _fsa[:0]
+	fsa = tokenizeSubjectIntoSlice(fsa[:0], filter)
 
 	// 1. See if we match any subs from fss.
 	// 2. If we match and the sseq is past ss.Last then we can use meta only.
@@ -2481,8 +2480,8 @@ func (mb *msgBlock) filteredPendingLocked(filter string, wc bool, sseq uint64) (
 		if !wc {
 			return subj == filter
 		}
-		tts := tokenizeSubjectIntoSlice(tsa[:0], subj)
-		return isSubsetMatchTokenized(tts, fts)
+		tsa = tokenizeSubjectIntoSlice(tsa[:0], subj)
+		return isSubsetMatchTokenized(tsa, fsa)
 	}
 
 	var havePartial bool
@@ -2897,8 +2896,9 @@ func (fs *fileStore) NumPending(sseq uint64, filter string, lastPerSubject bool)
 		return fs.state.LastSeq - sseq + 1, validThrough
 	}
 
-	var tsa, fsa [32]string
-	fts := tokenizeSubjectIntoSlice(fsa[:0], filter)
+	_tsa, _fsa := [32]string{}, [32]string{}
+	tsa, fsa := _tsa[:0], _fsa[:0]
+	fsa = tokenizeSubjectIntoSlice(fsa[:0], filter)
 
 	isMatch := func(subj string) bool {
 		if isAll {
@@ -2907,8 +2907,8 @@ func (fs *fileStore) NumPending(sseq uint64, filter string, lastPerSubject bool)
 		if !wc {
 			return subj == filter
 		}
-		tts := tokenizeSubjectIntoSlice(tsa[:0], subj)
-		return isSubsetMatchTokenized(tts, fts)
+		tsa = tokenizeSubjectIntoSlice(tsa[:0], subj)
+		return isSubsetMatchTokenized(tsa, fsa)
 	}
 
 	// Handle last by subject a bit differently.

diff --git a/server/memstore.go b/server/memstore.go
@@ -389,9 +389,9 @@ func (ms *memStore) filteredStateLocked(sseq uint64, filter string, lastPerSubje
 		}
 	}
 
-	tsa := [32]string{}
-	fsa := [32]string{}
-	fts := tokenizeSubjectIntoSlice(fsa[:0], filter)
+	_tsa, _fsa := [32]string{}, [32]string{}
+	tsa, fsa := _tsa[:0], _fsa[:0]
+	fsa = tokenizeSubjectIntoSlice(fsa[:0], filter)
 	wc := subjectHasWildcard(filter)
 
 	// 1. See if we match any subs from fss.
@@ -405,8 +405,8 @@ func (ms *memStore) filteredStateLocked(sseq uint64, filter string, lastPerSubje
 		if !wc {
 			return subj == filter
 		}
-		tts := tokenizeSubjectIntoSlice(tsa[:0], subj)
-		return isSubsetMatchTokenized(tts, fts)
+		tsa = tokenizeSubjectIntoSlice(tsa[:0], subj)
+		return isSubsetMatchTokenized(tsa, fsa)
 	}
 
 	update := func(fss *SimpleState) {
@@ -650,9 +650,9 @@ func (ms *memStore) SubjectsTotals(filterSubject string) map[string]uint64 {
 		return nil
 	}
 
-	tsa := [32]string{}
-	fsa := [32]string{}
-	fts := tokenizeSubjectIntoSlice(fsa[:0], filterSubject)
+	_tsa, _fsa := [32]string{}, [32]string{}
+	tsa, fsa := _tsa[:0], _fsa[:0]
+	fsa = tokenizeSubjectIntoSlice(fsa[:0], filterSubject)
 	isAll := filterSubject == _EMPTY_ || filterSubject == fwcs
 
 	fst := make(map[string]uint64)
@@ -661,7 +661,7 @@ func (ms *memStore) SubjectsTotals(filterSubject string) map[string]uint64 {
 		if isAll {
 			fst[subjs] = ss.Msgs
 		} else {
-			if tts := tokenizeSubjectIntoSlice(tsa[:0], subjs); isSubsetMatchTokenized(tts, fts) {
+			if tsa = tokenizeSubjectIntoSlice(tsa[:0], subjs); isSubsetMatchTokenized(tsa, fsa) {
 				fst[subjs] = ss.Msgs
 			}
 		}