Expand description
The implementation of a node for a history patricia tree
Structs
Wraps the label with which to find a node in storage.
A TreeNode represents a generic node of a Merkle Patricia Trei with ordering.
The main idea here is that the tree is changing at every epoch and that we do not need
to touch the state of a node, unless it changes.
The leaves of the tree represented by these nodes is supposed to allow for a user
to monitor the state of a key-value pair in the past.
We achieve this by including the epoch a leaf was added as part of the hash stored in it.
At a later time, we may need to access older sub-trees of the tree built with these nodes.
To facilitate this, we require this struct to include the last time a node was updated
as well as the oldest descendant it holds.
Represents a
TreeNode with its current state and potential future state.
Depending on the epoch which the Directory believes is the “most current”
version, we may need to load a slightly older version of the tree node. This is because
we can’t guarantee that a “publish” operation is globally atomic at the storage layer,
however we do assume record-level atomicity. This means that some records may be updated
to “future” values, and therefore we might need to temporarily read their previous values.Enums
There are three types of nodes: root, leaf and interior.
This enum is used to mark nodes using the node_type variable
of a TreeNode.
Functions
Create an empty root node.
Create a specific leaf node.