incrementalmerkletree/CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Rust's notion of Semantic Versioning.

[Unreleased]

Added

• Tree::get_witnessed_leaf has been added to allow a user to query for the leaf value of witnessed leaves by their position in the tree.

Changed

Changes to top-level types and traits:

• The Tree trait has substantial changes in this release. Hashes are no longer used in identifying nodes when generating authentication paths and removing witnesses; instead, these operations now use position information exclusively.
• Tree::authentication_path and Tree::remove_witness have both been changed to only take a position parameter, instead of both the leaf value and the position.
• Tree::current_leaf and Tree::witness have both been changed to only return the leaf value, instead of both the leaf value and the position.

Changes to the bridgetree module:

• The type of BridgeTree::saved and Checkpoint::forgotten have been changed from BTreeMap<(Position, H), usize> to BTreeMap<Position, usize>. This change is also reflected in the rturn type of the BridgeTree::witnessed_indices method.
• The Checkpoint type is no longer parameterized by H.
• BridgeTree::bridges has been split into two parts:
  • BridgeTree::prior_bridges now tracks past bridges not including the current frontier.
  • BridgeTree::current_bridge now tracks current mutable frontier.
• The signature of BridgeTree::from_parts has been modified to reflect these changes.
• A bug in BridgeTree::garbage_collect has been fixed. This bug caused garbage collection to in some cases incorrectly rewrite checkpointed bridge lengths, resulting in a condition where a rewind could panic after a GC operation.

Removed

• The Tree::Recording associated type and the relate record/play infrastructure has been removed; it was unused and added unnecessary complexity.

[0.3.0-beta.1] - 2022-03-22

Added

Additions to top-level types and traits:

• Position trait impls
  • From<Position> impl for usize
  • Add<usize> impl for Position
  • AddAssign<usize> impl for Position
  • TryFrom<u64> impl for Position
• Additions to the Tree trait
  • current_leaf method returns the position of the latest note appended to the tree along with the leaf value, if any.
  • current_position method returns the position of the latest note appended to the tree, if any.
  • is_witnessed method returns a boolean value indicating whether a leaf value has been marked for later construction of an authentication path at a specified position in the tree.

Additions to the bridgetree module:

• Added MerkleBridge methods
  • position returns the position of the tip of the frontier.
  • current_leaf returns the leaf value most recently appended to the frontier.
• Added Leaf::Value that returns the value of the leaf by reference.
• PartialEq and Eq impls for AuthFragment, MerkleBridge, and BridgeTreeError
• A number of constructor and accessor methods for Checkpoint have been added to facilitate serialization.
• BridgeTree::garbage_collect is a new method that prunes data for removed witnesses and inaccessable checkpoints beyond the max rewind depth.

Changed

Changes to top-level types and traits:

• Position now wraps a usize rather than a u64
• The following Tree methods now take an additional Position argument to support cases where leaf values may appear at multiple positions in the tree.
  • authentication_path
  • remove_witness
• The witness method now returns a tuple of the witnessed position and leaf hash, or None if the tree is empty, instead of a boolean value.
• The Clone constraint is removed for the NonEmptyFrontier::leaf_value method.

Changes to the bridgetree module:

• Most MerkleBridge methods now require the H type to be ordered.
• Changed the return type of MerkleBridge::auth_fragments from HashMap<usize, AuthFragment> to BTreeMap<Position, AuthFragment>
• MerkleBridge::successor arguments have changed.
• Checkpoint is now a struct, rather than an enum type, and contains information about witnessed nodes that have been marked for removal since the last checkpoint.
• BridgeTree now requires an Ord constraint for its leaf type, rather than a Hash constraint.

Removed

• TryFrom<Position> impl for usize
• bridgetree::Leaf::into_value removed in favor of bridgtree::leaf::value
• bridgetree::MerkleBridge::leaf_value method has been removed as a duplicate.
• bridgetree::BridgeTree::witnessable_leaves has been replaced by bridgetree::BridgeTree::witnessed_indices

[0.2.0] - 2022-03-22

Initial release!