From 732a6a36664b62af0877d0e1c6ba7d0c7c154cfe Mon Sep 17 00:00:00 2001 From: Evolution404 <35091674+Evolution404@users.noreply.github.com> Date: Sun, 20 Jun 2021 21:59:00 +0800 Subject: [PATCH] trie: small optimization of delete in fullNode case (#22979) When deleting in fullNode, and the new child node nn is not nil, there is no need to check the number of non-nil entries in the node. This is because the fullNode must've contained at least two children before deletion, so there must be another child node other than nn. Co-authored-by: Felix Lange --- trie/trie.go | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/trie/trie.go b/trie/trie.go index 7ed235fa8..e492a532c 100644 --- a/trie/trie.go +++ b/trie/trie.go @@ -405,6 +405,14 @@ func (t *Trie) delete(n node, prefix, key []byte) (bool, node, error) { n.flags = t.newFlag() n.Children[key[0]] = nn + // Because n is a full node, it must've contained at least two children + // before the delete operation. If the new child value is non-nil, n still + // has at least two children after the deletion, and cannot be reduced to + // a short node. + if nn != nil { + return true, n, nil + } + // Reduction: // Check how many non-nil entries are left after deleting and // reduce the full node to a short node if only one entry is // left. Since n must've contained at least two children