Return an empty list of node hashes when the compact merkle tree size is a power of 2 #273
Conversation
|
Would |
|
Welcome :) |
…n the tree size is a power of 2
rolandshoemaker
force-pushed
the
compact-tree-perfect
branch
from
a9d6509
to
5ad6555
Compare
| @@ -229,6 +229,9 @@ func (c CompactMerkleTree) Size() int64 { | |||
|
|
|||
| // Hashes returns a copy of the set of node hashes that comprise the compact representation of the tree. | |||
| func (c CompactMerkleTree) Hashes() [][]byte { | |||
| if isPerfectTree(c.size) { | |||
| return [][]byte{} | |||
There was a problem hiding this comment.
+1 to the suggestion of returning nil here instead.
There was a problem hiding this comment.
Thanks for fixing this. I'm happy for this to be merged as-is (with the minor return nil change).
-- background --
An alternative (but riskier) approach would be to have AddLeafHash clear the CompactMerkleTree.nodes slice when the leaf addition takes the tree to a perfect size. It would be a considerably more invasive change than the one I did in d1ee609 and I didn't do that at the time because I didn't want to risk introducing any kind of corruption into the compact merkle tree.
If AddLeafHash did work that way, it'd then be possible for checkUnusedNodesInvariant() to complain about CompactMerkleTree.nodes being non-empty on perfect tree sizes.
Dipping my toes into this code base with (what seems to me) a rather simple issue, feel free to tell me I've misunderstood the problem!
This change reuses the existing
isPerfectTreemethod to check if the tree size is a power of two inCompactMerkleTree.Hashesand returns[][]byte{}if so. Also updates tests to reflect this new behavior.Fixes #200.