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Improve last msg lookup (KV Get) when subject is a literal subject.

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Signed-off-by: Derek Collison <derek@nats.io>
This commit is contained in:
Derek Collison
2023-06-10 13:16:13 -07:00
parent 8c513ad2c2
commit f81bc80676
2 changed files with 16 additions and 3 deletions
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11
server/filestore.go
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@@ -4665,7 +4665,16 @@ func (fs *fileStore) loadLast(subj string, sm *StoreMsg) (lsm *StoreMsg, err err
mb.mu.Unlock()
return nil, err
}
_, _, l := mb.filteredPendingLocked(subj, wc, mb.first.seq)
var l uint64
// Optimize if subject is not a wildcard.
if !wc {
if ss := mb.fss[subj]; ss != nil {
l = ss.Last
}
}
if l == 0 {
_, _, l = mb.filteredPendingLocked(subj, wc, mb.first.seq)
}
if l > 0 {
if mb.cacheNotLoaded() {
if err := mb.loadMsgsWithLock(); err != nil {

8
server/memstore.go
View File

@@ -864,6 +864,10 @@ func (ms *memStore) LoadLastMsg(subject string, smp *StoreMsg) (*StoreMsg, error
if subject == _EMPTY_ || subject == fwcs {
sm, ok = ms.msgs[ms.state.LastSeq]
} else if subjectIsLiteral(subject) {
if ss := ms.fss[subject]; ss != nil && ss.Msgs > 0 {
sm, ok = ms.msgs[ss.Last]
}
} else if ss := ms.filteredStateLocked(1, subject, true); ss.Msgs > 0 {
sm, ok = ms.msgs[ss.Last]
}
@@ -895,8 +899,8 @@ func (ms *memStore) LoadNextMsg(filter string, wc bool, start uint64, smp *Store
isAll := filter == _EMPTY_ || filter == fwcs
// Skip scan of mb.fss is number of messages in the block are less than
// 1/2 the number of subjects in mb.fss. Or we have a wc and lots of fss entries.
// Skip scan of ms.fss is number of messages in the block are less than
// 1/2 the number of subjects in ms.fss. Or we have a wc and lots of fss entries.
const linearScanMaxFSS = 256
doLinearScan := isAll || 2*int(ms.state.LastSeq-start) < len(ms.fss) || (wc && len(ms.fss) > linearScanMaxFSS)