Struct fork_tree::ForkTree

pub struct ForkTree<H, N, V> { /* fields omitted */ }

A tree data structure that stores several nodes across multiple branches. Top-level branches are called roots. The tree has functionality for finalizing nodes, which means that that node is traversed, and all competing branches are pruned. It also guarantees that nodes in the tree are finalized in order. Each node is uniquely identified by its hash but can be ordered by its number. In order to build the tree an external function must be provided when interacting with the tree to establish a node's ancestry.

Methods

impl<H, N, V> ForkTree<H, N, V> where
    H: PartialEq + Clone,
    N: Ord + Clone,
    V: Clone, 

pub fn prune<F, E, P>(
    &mut self,
    hash: &H,
    number: &N,
    is_descendent_of: &F,
    predicate: &P
) -> Result<impl Iterator<Item = (H, N, V)>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Prune the tree, removing all non-canonical nodes. We find the node in the tree that is the deepest ancestor of the given hash and that passes the given predicate. If such a node exists, we re-root the tree to this node. Otherwise the tree remains unchanged. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base).

Returns all pruned node data.

impl<H, N, V> ForkTree<H, N, V> where
    H: PartialEq,
    N: Ord, 

pub fn new() -> ForkTree<H, N, V>

Create a new empty tree.

pub fn rebalance(&mut self)

Rebalance the tree, i.e. sort child nodes by max branch depth (decreasing).

Most operations in the tree are performed with depth-first search starting from the leftmost node at every level, since this tree is meant to be used in a blockchain context, a good heuristic is that the node we'll be looking for at any point will likely be in one of the deepest chains (i.e. the longest ones).

pub fn import<F, E>(
    &mut self,
    hash: H,
    number: N,
    data: V,
    is_descendent_of: &F
) -> Result<bool, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>, 

Import a new node into the tree. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base). This method assumes that nodes in the same branch are imported in order.

Returns true if the imported node is a root.

pub fn roots(&self) -> impl Iterator<Item = (&H, &N, &V)>

Iterates over the existing roots in the tree.

pub fn iter(&self) -> impl Iterator<Item = (&H, &N, &V)>

Iterates the nodes in the tree in pre-order.

pub fn find_node_where<F, E, P>(
    &self,
    hash: &H,
    number: &N,
    is_descendent_of: &F,
    predicate: &P
) -> Result<Option<&Node<H, N, V>>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Find a node in the tree that is the deepest ancestor of the given block hash and which passes the given predicate. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base).

pub fn map<VT, F>(self, f: &mut F) -> ForkTree<H, N, VT> where
    F: FnMut(&H, &N, V) -> VT, 

Map fork tree into values of new types.

pub fn find_node_where_mut<F, E, P>(
    &mut self,
    hash: &H,
    number: &N,
    is_descendent_of: &F,
    predicate: &P
) -> Result<Option<&mut Node<H, N, V>>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Same as find_node_where, but returns mutable reference.

pub fn find_node_index_where<F, E, P>(
    &self,
    hash: &H,
    number: &N,
    is_descendent_of: &F,
    predicate: &P
) -> Result<Option<Vec<usize>>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Same as find_node_where, but returns indexes.

pub fn finalize_root(&mut self, hash: &H) -> Option<V>

Finalize a root in the tree and return it, return None in case no root with the given hash exists. All other roots are pruned, and the children of the finalized node become the new roots.

pub fn finalize<F, E>(
    &mut self,
    hash: &H,
    number: N,
    is_descendent_of: &F
) -> Result<FinalizationResult<V>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>, 

Finalize a node in the tree. This method will make sure that the node being finalized is either an existing root (and return its data), or a node from a competing branch (not in the tree), tree pruning is done accordingly. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base).

pub fn finalize_with_ancestors<F, E>(
    &mut self,
    hash: &H,
    number: N,
    is_descendent_of: &F
) -> Result<FinalizationResult<V>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>, 

Finalize a node in the tree and all its ancestors. The given function is_descendent_of should return true if the second hash (target) is

pub fn finalizes_any_with_descendent_if<F, P, E>(
    &self,
    hash: &H,
    number: N,
    is_descendent_of: &F,
    predicate: P
) -> Result<Option<bool>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Checks if any node in the tree is finalized by either finalizing the node itself or a child node that's not in the tree, guaranteeing that the node being finalized isn't a descendent of any of the node's children. Returns Some(true) if the node being finalized is a root, Some(false) if the node being finalized is not a root, and None if no node in the tree is finalized. The given predicate is checked on the prospective finalized root and must pass for finalization to occur. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base).

pub fn finalize_with_descendent_if<F, P, E>(
    &mut self,
    hash: &H,
    number: N,
    is_descendent_of: &F,
    predicate: P
) -> Result<FinalizationResult<V>, Error<E>> where
    E: Error,
    F: Fn(&H, &H) -> Result<bool, E>,
    P: Fn(&V) -> bool, 

Finalize a root in the tree by either finalizing the node itself or a child node that's not in the tree, guaranteeing that the node being finalized isn't a descendent of any of the root's children. The given predicate is checked on the prospective finalized root and must pass for finalization to occur. The given function is_descendent_of should return true if the second hash (target) is a descendent of the first hash (base).

Trait Implementations

impl<H: Clone, N: Clone, V: Clone> Clone for ForkTree<H, N, V>

fn clone(&self) -> ForkTree<H, N, V>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<H: Debug, N: Debug, V: Debug> Debug for ForkTree<H, N, V>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<H, N, V> Decode for ForkTree<H, N, V> where
    Vec<Node<H, N, V>>: Decode,
    Vec<Node<H, N, V>>: Decode,
    Option<N>: Decode,
    Option<N>: Decode, 

fn decode<DecIn: Input>(input: &mut DecIn) -> Result<Self, Error>

Attempt to deserialise the value from input.

impl<H, N, V> Encode for ForkTree<H, N, V> where
    Vec<Node<H, N, V>>: Encode,
    Vec<Node<H, N, V>>: Encode,
    Option<N>: Encode,
    Option<N>: Encode, 

fn encode_to<EncOut: Output>(&self, dest: &mut EncOut)

Convert self to a slice and append it to the destination.

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn using_encoded<R, F>(&self, f: F) -> R where
    F: FnOnce(&[u8]) -> R, 

Convert self to a slice and then invoke the given closure with it.

impl<H, N, V> EncodeLike<ForkTree<H, N, V>> for ForkTree<H, N, V> where
    Vec<Node<H, N, V>>: Encode,
    Vec<Node<H, N, V>>: Encode,
    Option<N>: Encode,
    Option<N>: Encode, 

impl<H: PartialEq, N: PartialEq, V: PartialEq> PartialEq<ForkTree<H, N, V>> for ForkTree<H, N, V>

fn eq(&self, other: &ForkTree<H, N, V>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &ForkTree<H, N, V>) -> bool

This method tests for !=.

impl<H, N, V> StructuralPartialEq for ForkTree<H, N, V>