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leveldb/memdb: avoid repeated comparisons #384

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leveldb/memdb: avoid repeated comparisons #384

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71d7460
leveldb/memdb: avoid repeated comparisons
holiman Dec 8, 2021
c612a5c
memdb: fix the case where we find an early exact match
holiman Dec 9, 2021
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8 changes: 7 additions & 1 deletion leveldb/memdb/memdb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -211,17 +211,23 @@ func (p *DB) randHeight() (h int) {
func (p *DB) findGE(key []byte, prev bool) (int, bool) {
node := 0
h := p.maxHeight - 1
visited := 0
for {
next := p.nodeData[node+nNext+h]
cmp := 1
if next != 0 {
if next != 0 && next != visited {
o := p.nodeData[next]
cmp = p.cmp.Compare(p.kvData[o:o+p.nodeData[next+nKey]], key)
}
if cmp < 0 {
// Keep searching in this list
node = next
} else {
if next != 0 && cmp != 0 {
// If we go down further, we can skip this element if we
// encounter it on a lower level.
visited = next
}
if prev {
p.prevNode[h] = node
} else if cmp == 0 {
Expand Down