pub trait Outboard {
// Required methods
fn root(&self) -> Hash;
fn tree(&self) -> BaoTree;
fn load(&self, node: TreeNode) -> Result<Option<(Hash, Hash)>>;
}Expand description
A binary merkle tree for blake3 hashes of a blob.
This trait contains information about the geometry of the tree, the root hash, and a method to load the hashes at a given node.
It is up to the implementor to decide how to store the hashes.
In the original bao crate, the hashes are stored in a file in pre order. This is implemented for a generic io object in super::outboard::PreOrderOutboard and for a memory region in super::outboard::PreOrderMemOutboard.
For files that grow over time, it is more efficient to store the hashes in post order. This is implemented for a generic io object in super::outboard::PostOrderOutboard and for a memory region in super::outboard::PostOrderMemOutboard.
If you use a different storage engine, you can implement this trait for it. E.g. you could store the hashes in a database and use the node number as the key.