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incrementalmerkletree
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Move `PrunableTree` and `RetentionFlags` into `prunable` submodule 

Co-authored-by: Kris Nuttycombe <kris@nutty.land>
This commit is contained in:
Jack Grigg 2023-07-05 18:57:06 +00:00
parent 3b05192538
commit 0f15a57cb5
2 changed files with 417 additions and 399 deletions
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403
shardtree/src/lib.rs
View File

@ -1,4 +1,3 @@
use bitflags::bitflags;
use core::convert::TryFrom;
use core::fmt::{self, Debug, Display};
use core::ops::Range;
@ -17,300 +16,8 @@ use incrementalmerkletree::witness::IncrementalWitness;
mod tree;
pub use self::tree::{Node, Tree};
bitflags! {
pub struct RetentionFlags: u8 {
/// An leaf with `EPHEMERAL` retention can be pruned as soon as we are certain that it is not part
/// of the witness for a leaf with [`CHECKPOINT`] or [`MARKED`] retention.
///
/// [`CHECKPOINT`]: RetentionFlags::CHECKPOINT
/// [`MARKED`]: RetentionFlags::MARKED
const EPHEMERAL = 0b00000000;
/// A leaf with `CHECKPOINT` retention can be pruned when there are more than `max_checkpoints`
/// additional checkpoint leaves, if it is not also a marked leaf.
const CHECKPOINT = 0b00000001;
/// A leaf with `MARKED` retention can be pruned only as a consequence of an explicit deletion
/// action.
const MARKED = 0b00000010;
}
}
impl RetentionFlags {
pub fn is_checkpoint(&self) -> bool {
(*self & RetentionFlags::CHECKPOINT) == RetentionFlags::CHECKPOINT
}
pub fn is_marked(&self) -> bool {
(*self & RetentionFlags::MARKED) == RetentionFlags::MARKED
}
}
impl<'a, C> From<&'a Retention<C>> for RetentionFlags {
fn from(retention: &'a Retention<C>) -> Self {
match retention {
Retention::Ephemeral => RetentionFlags::EPHEMERAL,
Retention::Checkpoint { is_marked, .. } => {
if *is_marked {
RetentionFlags::CHECKPOINT | RetentionFlags::MARKED
} else {
RetentionFlags::CHECKPOINT
}
}
Retention::Marked => RetentionFlags::MARKED,
}
}
}
impl<C> From<Retention<C>> for RetentionFlags {
fn from(retention: Retention<C>) -> Self {
RetentionFlags::from(&retention)
}
}
pub type PrunableTree<H> = Tree<Option<Rc<H>>, (H, RetentionFlags)>;
impl<H: Hashable + Clone + PartialEq> PrunableTree<H> {
/// Returns the the value if this is a leaf.
pub fn leaf_value(&self) -> Option<&H> {
self.0.leaf_value().map(|(h, _)| h)
}
/// Returns the cached root value with which the tree has been annotated for this node if it is
/// available, otherwise return the value if this is a leaf.
pub fn node_value(&self) -> Option<&H> {
self.0.annotation().map_or_else(
|| self.leaf_value(),
|rc_opt| rc_opt.as_ref().map(|rc| rc.as_ref()),
)
}
/// Returns whether or not this tree is a leaf with `Marked` retention.
pub fn is_marked_leaf(&self) -> bool {
self.0
.leaf_value()
.map_or(false, |(_, retention)| retention.is_marked())
}
/// Determines whether a tree has any [`Retention::Marked`] nodes.
pub fn contains_marked(&self) -> bool {
match &self.0 {
Node::Parent { left, right, .. } => left.contains_marked() || right.contains_marked(),
Node::Leaf { value: (_, r) } => r.is_marked(),
Node::Nil => false,
}
}
/// Returns the Merkle root of this tree, given the address of the root node, or
/// a vector of the addresses of `Nil` nodes that inhibited the computation of
/// such a root.
///
/// ### Parameters:
/// * `truncate_at` An inclusive lower bound on positions in the tree beyond which all leaf
/// values will be treated as `Nil`.
pub fn root_hash(&self, root_addr: Address, truncate_at: Position) -> Result<H, Vec<Address>> {
if truncate_at <= root_addr.position_range_start() {
// we are in the part of the tree where we're generating empty roots,
// so no need to inspect the tree
Ok(H::empty_root(root_addr.level()))
} else {
match self {
Tree(Node::Parent { ann, left, right }) => ann
.as_ref()
.filter(|_| truncate_at >= root_addr.position_range_end())
.map_or_else(
|| {
// Compute the roots of the left and right children and hash them
// together.
let (l_addr, r_addr) = root_addr.children().unwrap();
accumulate_result_with(
left.root_hash(l_addr, truncate_at),
right.root_hash(r_addr, truncate_at),
|left_root, right_root| {
H::combine(l_addr.level(), &left_root, &right_root)
},
)
},
|rc| {
// Since we have an annotation on the root, and we are not truncating
// within this subtree, we can just use the cached value.
Ok(rc.as_ref().clone())
},
),
Tree(Node::Leaf { value }) => {
if truncate_at >= root_addr.position_range_end() {
// no truncation of this leaf is necessary, just use it
Ok(value.0.clone())
} else {
// we have a leaf value that is a subtree root created by hashing together
// the roots of child subtrees, but truncation would require that that leaf
// value be "split" into its constituent parts, which we can't do so we
// return an error
Err(vec![root_addr])
}
}
Tree(Node::Nil) => Err(vec![root_addr]),
}
}
}
/// Returns a vector of the positions of [`Node::Leaf`] values in the tree having
/// [`MARKED`](RetentionFlags::MARKED) retention.
///
/// Computing the set of marked positions requires a full traversal of the tree, and so should
/// be considered to be a somewhat expensive operation.
pub fn marked_positions(&self, root_addr: Address) -> BTreeSet<Position> {
match &self.0 {
Node::Parent { left, right, .. } => {
// We should never construct parent nodes where both children are Nil.
// While we could handle that here, if we encountered that case it would
// be indicative of a programming error elsewhere and so we assert instead.
assert!(!(left.0.is_nil() && right.0.is_nil()));
let (left_root, right_root) = root_addr
.children()
.expect("A parent node cannot appear at level 0");
let mut left_incomplete = left.marked_positions(left_root);
let mut right_incomplete = right.marked_positions(right_root);
left_incomplete.append(&mut right_incomplete);
left_incomplete
}
Node::Leaf {
value: (_, retention),
} => {
let mut result = BTreeSet::new();
if root_addr.level() == 0.into() && retention.is_marked() {
result.insert(Position::from(root_addr.index()));
}
result
}
Node::Nil => BTreeSet::new(),
}
}
/// Prunes the tree by hashing together ephemeral sibling nodes.
///
/// `level` must be the level of the root of the node being pruned.
pub fn prune(self, level: Level) -> Self {
match self {
Tree(Node::Parent { ann, left, right }) => Tree::unite(
level,
ann,
left.as_ref().clone().prune(level - 1),
right.as_ref().clone().prune(level - 1),
),
other => other,
}
}
/// Merge two subtrees having the same root address.
///
/// The merge operation is checked to be strictly additive and returns an error if merging
/// would cause information loss or if a conflict between root hashes occurs at a node. The
/// returned error contains the address of the node where such a conflict occurred.
pub fn merge_checked(self, root_addr: Address, other: Self) -> Result<Self, Address> {
#[allow(clippy::type_complexity)]
fn go<H: Hashable + Clone + PartialEq>(
addr: Address,
t0: PrunableTree<H>,
t1: PrunableTree<H>,
) -> Result<PrunableTree<H>, Address> {
// Require that any roots the we compute will not be default-filled by picking
// a starting valid fill point that is outside the range of leaf positions.
let no_default_fill = addr.position_range_end();
match (t0, t1) {
(Tree(Node::Nil), other) | (other, Tree(Node::Nil)) => Ok(other),
(Tree(Node::Leaf { value: vl }), Tree(Node::Leaf { value: vr })) => {
if vl == vr {
Ok(Tree(Node::Leaf { value: vl }))
} else {
Err(addr)
}
}
(Tree(Node::Leaf { value }), parent @ Tree(Node::Parent { .. }))
| (parent @ Tree(Node::Parent { .. }), Tree(Node::Leaf { value })) => {
if parent
.root_hash(addr, no_default_fill)
.iter()
.all(|r| r == &value.0)
{
Ok(parent.reannotate_root(Some(Rc::new(value.0))))
} else {
Err(addr)
}
}
(lparent, rparent) => {
let lroot = lparent.root_hash(addr, no_default_fill).ok();
let rroot = rparent.root_hash(addr, no_default_fill).ok();
// If both parents share the same root hash (or if one of them is absent),
// they can be merged
if lroot.zip(rroot).iter().all(|(l, r)| l == r) {
// using `if let` here to bind variables; we need to borrow the trees for
// root hash calculation but binding the children of the parent node
// interferes with binding a reference to the parent.
if let (
Tree(Node::Parent {
ann: lann,
left: ll,
right: lr,
}),
Tree(Node::Parent {
ann: rann,
left: rl,
right: rr,
}),
) = (lparent, rparent)
{
let (l_addr, r_addr) = addr.children().unwrap();
Ok(Tree::unite(
addr.level() - 1,
lann.or(rann),
go(l_addr, ll.as_ref().clone(), rl.as_ref().clone())?,
go(r_addr, lr.as_ref().clone(), rr.as_ref().clone())?,
))
} else {
unreachable!()
}
} else {
Err(addr)
}
}
}
}
go(root_addr, self, other)
}
/// Unite two nodes by either constructing a new parent node, or, if both nodes are ephemeral
/// leaves or Nil, constructing a replacement root by hashing leaf values together (or a
/// replacement `Nil` value).
///
/// `level` must be the level of the two nodes that are being joined.
fn unite(level: Level, ann: Option<Rc<H>>, left: Self, right: Self) -> Self {
match (left, right) {
(Tree(Node::Nil), Tree(Node::Nil)) => Tree(Node::Nil),
(Tree(Node::Leaf { value: lv }), Tree(Node::Leaf { value: rv }))
// we can prune right-hand leaves that are not marked; if a leaf
// is a checkpoint then that information will be propagated to
// the replacement leaf
if lv.1 == RetentionFlags::EPHEMERAL && (rv.1 & RetentionFlags::MARKED) == RetentionFlags::EPHEMERAL =>
{
Tree(
Node::Leaf {
value: (H::combine(level, &lv.0, &rv.0), rv.1),
},
)
}
(left, right) => Tree(
Node::Parent {
ann,
left: Rc::new(left),
right: Rc::new(right),
},
),
}
}
}
mod prunable;
pub use self::prunable::{PrunableTree, RetentionFlags};
/// A binary Merkle tree with its root at the given address.
#[derive(Clone, Debug, PartialEq, Eq)]
@ -3603,7 +3310,6 @@ pub mod testing {
mod tests {
use assert_matches::assert_matches;
use proptest::prelude::*;
use std::collections::BTreeSet;
use incrementalmerkletree::{
frontier::NonEmptyFrontier,
@ -3622,8 +3328,8 @@ mod tests {
check_witness_with_pruned_subtrees,
},
tree::tests::{leaf, nil, parent, str_leaf},
InsertionError, LocatedPrunableTree, LocatedTree, MemoryShardStore, PrunableTree,
QueryError, RetentionFlags, ShardTree,
InsertionError, LocatedPrunableTree, LocatedTree, MemoryShardStore, QueryError,
RetentionFlags, ShardTree,
};
#[cfg(feature = "legacy-api")]
@ -3632,36 +3338,6 @@ mod tests {
#[cfg(feature = "legacy-api")]
use crate::Tree;
#[test]
fn tree_root() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::EPHEMERAL)),
);
assert_eq!(
t.root_hash(Address::from_parts(Level::from(1), 0), Position::from(2)),
Ok("ab".to_string())
);
let t0 = parent(nil(), t.clone());
assert_eq!(
t0.root_hash(Address::from_parts(Level::from(2), 0), Position::from(4)),
Err(vec![Address::from_parts(Level::from(1), 0)])
);
// Check root computation with truncation
let t1 = parent(t, nil());
assert_eq!(
t1.root_hash(Address::from_parts(Level::from(2), 0), Position::from(2)),
Ok("ab__".to_string())
);
assert_eq!(
t1.root_hash(Address::from_parts(Level::from(2), 0), Position::from(3)),
Err(vec![Address::from_parts(Level::from(1), 1)])
);
}
#[test]
fn located_prunable_tree_insert_subtree() {
let t: LocatedPrunableTree<String> = LocatedTree {
@ -3735,77 +3411,6 @@ mod tests {
);
}
#[test]
fn tree_marked_positions() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::MARKED)),
);
assert_eq!(
t.marked_positions(Address::from_parts(Level::from(1), 0)),
BTreeSet::from([Position::from(1)])
);
let t0 = parent(t.clone(), t);
assert_eq!(
t0.marked_positions(Address::from_parts(Level::from(2), 1)),
BTreeSet::from([Position::from(5), Position::from(7)])
);
}
#[test]
fn tree_prune() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::EPHEMERAL)),
);
assert_eq!(
t.clone().prune(Level::from(1)),
leaf(("ab".to_string(), RetentionFlags::EPHEMERAL))
);
let t0 = parent(leaf(("c".to_string(), RetentionFlags::MARKED)), t);
assert_eq!(
t0.prune(Level::from(2)),
parent(
leaf(("c".to_string(), RetentionFlags::MARKED)),
leaf(("ab".to_string(), RetentionFlags::EPHEMERAL))
)
);
}
#[test]
fn tree_merge_checked() {
let t0: PrunableTree<String> =
parent(leaf(("a".to_string(), RetentionFlags::EPHEMERAL)), nil());
let t1: PrunableTree<String> =
parent(nil(), leaf(("b".to_string(), RetentionFlags::EPHEMERAL)));
assert_eq!(
t0.clone()
.merge_checked(Address::from_parts(1.into(), 0), t1.clone()),
Ok(leaf(("ab".to_string(), RetentionFlags::EPHEMERAL)))
);
let t2: PrunableTree<String> =
parent(leaf(("c".to_string(), RetentionFlags::EPHEMERAL)), nil());
assert_eq!(
t0.clone()
.merge_checked(Address::from_parts(1.into(), 0), t2.clone()),
Err(Address::from_parts(0.into(), 0))
);
let t3: PrunableTree<String> = parent(t0, t2);
let t4: PrunableTree<String> = parent(t1.clone(), t1);
assert_eq!(
t3.merge_checked(Address::from_parts(2.into(), 0), t4),
Ok(leaf(("abcb".to_string(), RetentionFlags::EPHEMERAL)))
);
}
#[test]
fn located_tree() {
let l = parent(str_leaf("a"), str_leaf("b"));

413
shardtree/src/prunable.rs Normal file
View File

@ -0,0 +1,413 @@
use std::collections::BTreeSet;
use std::rc::Rc;
use bitflags::bitflags;
use incrementalmerkletree::{Address, Hashable, Level, Position, Retention};
use crate::{accumulate_result_with, Node, Tree};
bitflags! {
pub struct RetentionFlags: u8 {
/// An leaf with `EPHEMERAL` retention can be pruned as soon as we are certain that it is not part
/// of the witness for a leaf with [`CHECKPOINT`] or [`MARKED`] retention.
///
/// [`CHECKPOINT`]: RetentionFlags::CHECKPOINT
/// [`MARKED`]: RetentionFlags::MARKED
const EPHEMERAL = 0b00000000;
/// A leaf with `CHECKPOINT` retention can be pruned when there are more than `max_checkpoints`
/// additional checkpoint leaves, if it is not also a marked leaf.
const CHECKPOINT = 0b00000001;
/// A leaf with `MARKED` retention can be pruned only as a consequence of an explicit deletion
/// action.
const MARKED = 0b00000010;
}
}
impl RetentionFlags {
pub fn is_checkpoint(&self) -> bool {
(*self & RetentionFlags::CHECKPOINT) == RetentionFlags::CHECKPOINT
}
pub fn is_marked(&self) -> bool {
(*self & RetentionFlags::MARKED) == RetentionFlags::MARKED
}
}
impl<'a, C> From<&'a Retention<C>> for RetentionFlags {
fn from(retention: &'a Retention<C>) -> Self {
match retention {
Retention::Ephemeral => RetentionFlags::EPHEMERAL,
Retention::Checkpoint { is_marked, .. } => {
if *is_marked {
RetentionFlags::CHECKPOINT | RetentionFlags::MARKED
} else {
RetentionFlags::CHECKPOINT
}
}
Retention::Marked => RetentionFlags::MARKED,
}
}
}
impl<C> From<Retention<C>> for RetentionFlags {
fn from(retention: Retention<C>) -> Self {
RetentionFlags::from(&retention)
}
}
pub type PrunableTree<H> = Tree<Option<Rc<H>>, (H, RetentionFlags)>;
impl<H: Hashable + Clone + PartialEq> PrunableTree<H> {
/// Returns the the value if this is a leaf.
pub fn leaf_value(&self) -> Option<&H> {
self.0.leaf_value().map(|(h, _)| h)
}
/// Returns the cached root value with which the tree has been annotated for this node if it is
/// available, otherwise return the value if this is a leaf.
pub fn node_value(&self) -> Option<&H> {
self.0.annotation().map_or_else(
|| self.leaf_value(),
|rc_opt| rc_opt.as_ref().map(|rc| rc.as_ref()),
)
}
/// Returns whether or not this tree is a leaf with `Marked` retention.
pub fn is_marked_leaf(&self) -> bool {
self.0
.leaf_value()
.map_or(false, |(_, retention)| retention.is_marked())
}
/// Determines whether a tree has any [`Retention::Marked`] nodes.
pub fn contains_marked(&self) -> bool {
match &self.0 {
Node::Parent { left, right, .. } => left.contains_marked() || right.contains_marked(),
Node::Leaf { value: (_, r) } => r.is_marked(),
Node::Nil => false,
}
}
/// Returns the Merkle root of this tree, given the address of the root node, or
/// a vector of the addresses of `Nil` nodes that inhibited the computation of
/// such a root.
///
/// ### Parameters:
/// * `truncate_at` An inclusive lower bound on positions in the tree beyond which all leaf
/// values will be treated as `Nil`.
pub fn root_hash(&self, root_addr: Address, truncate_at: Position) -> Result<H, Vec<Address>> {
if truncate_at <= root_addr.position_range_start() {
// we are in the part of the tree where we're generating empty roots,
// so no need to inspect the tree
Ok(H::empty_root(root_addr.level()))
} else {
match self {
Tree(Node::Parent { ann, left, right }) => ann
.as_ref()
.filter(|_| truncate_at >= root_addr.position_range_end())
.map_or_else(
|| {
// Compute the roots of the left and right children and hash them
// together.
let (l_addr, r_addr) = root_addr.children().unwrap();
accumulate_result_with(
left.root_hash(l_addr, truncate_at),
right.root_hash(r_addr, truncate_at),
|left_root, right_root| {
H::combine(l_addr.level(), &left_root, &right_root)
},
)
},
|rc| {
// Since we have an annotation on the root, and we are not truncating
// within this subtree, we can just use the cached value.
Ok(rc.as_ref().clone())
},
),
Tree(Node::Leaf { value }) => {
if truncate_at >= root_addr.position_range_end() {
// no truncation of this leaf is necessary, just use it
Ok(value.0.clone())
} else {
// we have a leaf value that is a subtree root created by hashing together
// the roots of child subtrees, but truncation would require that that leaf
// value be "split" into its constituent parts, which we can't do so we
// return an error
Err(vec![root_addr])
}
}
Tree(Node::Nil) => Err(vec![root_addr]),
}
}
}
/// Returns a vector of the positions of [`Node::Leaf`] values in the tree having
/// [`MARKED`](RetentionFlags::MARKED) retention.
///
/// Computing the set of marked positions requires a full traversal of the tree, and so should
/// be considered to be a somewhat expensive operation.
pub fn marked_positions(&self, root_addr: Address) -> BTreeSet<Position> {
match &self.0 {
Node::Parent { left, right, .. } => {
// We should never construct parent nodes where both children are Nil.
// While we could handle that here, if we encountered that case it would
// be indicative of a programming error elsewhere and so we assert instead.
assert!(!(left.0.is_nil() && right.0.is_nil()));
let (left_root, right_root) = root_addr
.children()
.expect("A parent node cannot appear at level 0");
let mut left_incomplete = left.marked_positions(left_root);
let mut right_incomplete = right.marked_positions(right_root);
left_incomplete.append(&mut right_incomplete);
left_incomplete
}
Node::Leaf {
value: (_, retention),
} => {
let mut result = BTreeSet::new();
if root_addr.level() == 0.into() && retention.is_marked() {
result.insert(Position::from(root_addr.index()));
}
result
}
Node::Nil => BTreeSet::new(),
}
}
/// Prunes the tree by hashing together ephemeral sibling nodes.
///
/// `level` must be the level of the root of the node being pruned.
pub fn prune(self, level: Level) -> Self {
match self {
Tree(Node::Parent { ann, left, right }) => Tree::unite(
level,
ann,
left.as_ref().clone().prune(level - 1),
right.as_ref().clone().prune(level - 1),
),
other => other,
}
}
/// Merge two subtrees having the same root address.
///
/// The merge operation is checked to be strictly additive and returns an error if merging
/// would cause information loss or if a conflict between root hashes occurs at a node. The
/// returned error contains the address of the node where such a conflict occurred.
pub fn merge_checked(self, root_addr: Address, other: Self) -> Result<Self, Address> {
#[allow(clippy::type_complexity)]
fn go<H: Hashable + Clone + PartialEq>(
addr: Address,
t0: PrunableTree<H>,
t1: PrunableTree<H>,
) -> Result<PrunableTree<H>, Address> {
// Require that any roots the we compute will not be default-filled by picking
// a starting valid fill point that is outside the range of leaf positions.
let no_default_fill = addr.position_range_end();
match (t0, t1) {
(Tree(Node::Nil), other) | (other, Tree(Node::Nil)) => Ok(other),
(Tree(Node::Leaf { value: vl }), Tree(Node::Leaf { value: vr })) => {
if vl == vr {
Ok(Tree(Node::Leaf { value: vl }))
} else {
Err(addr)
}
}
(Tree(Node::Leaf { value }), parent @ Tree(Node::Parent { .. }))
| (parent @ Tree(Node::Parent { .. }), Tree(Node::Leaf { value })) => {
if parent
.root_hash(addr, no_default_fill)
.iter()
.all(|r| r == &value.0)
{
Ok(parent.reannotate_root(Some(Rc::new(value.0))))
} else {
Err(addr)
}
}
(lparent, rparent) => {
let lroot = lparent.root_hash(addr, no_default_fill).ok();
let rroot = rparent.root_hash(addr, no_default_fill).ok();
// If both parents share the same root hash (or if one of them is absent),
// they can be merged
if lroot.zip(rroot).iter().all(|(l, r)| l == r) {
// using `if let` here to bind variables; we need to borrow the trees for
// root hash calculation but binding the children of the parent node
// interferes with binding a reference to the parent.
if let (
Tree(Node::Parent {
ann: lann,
left: ll,
right: lr,
}),
Tree(Node::Parent {
ann: rann,
left: rl,
right: rr,
}),
) = (lparent, rparent)
{
let (l_addr, r_addr) = addr.children().unwrap();
Ok(Tree::unite(
addr.level() - 1,
lann.or(rann),
go(l_addr, ll.as_ref().clone(), rl.as_ref().clone())?,
go(r_addr, lr.as_ref().clone(), rr.as_ref().clone())?,
))
} else {
unreachable!()
}
} else {
Err(addr)
}
}
}
}
go(root_addr, self, other)
}
/// Unite two nodes by either constructing a new parent node, or, if both nodes are ephemeral
/// leaves or Nil, constructing a replacement root by hashing leaf values together (or a
/// replacement `Nil` value).
///
/// `level` must be the level of the two nodes that are being joined.
pub(crate) fn unite(level: Level, ann: Option<Rc<H>>, left: Self, right: Self) -> Self {
match (left, right) {
(Tree(Node::Nil), Tree(Node::Nil)) => Tree(Node::Nil),
(Tree(Node::Leaf { value: lv }), Tree(Node::Leaf { value: rv }))
// we can prune right-hand leaves that are not marked; if a leaf
// is a checkpoint then that information will be propagated to
// the replacement leaf
if lv.1 == RetentionFlags::EPHEMERAL && (rv.1 & RetentionFlags::MARKED) == RetentionFlags::EPHEMERAL =>
{
Tree(
Node::Leaf {
value: (H::combine(level, &lv.0, &rv.0), rv.1),
},
)
}
(left, right) => Tree(
Node::Parent {
ann,
left: Rc::new(left),
right: Rc::new(right),
},
),
}
}
}
#[cfg(test)]
mod tests {
use std::collections::BTreeSet;
use incrementalmerkletree::{Address, Level, Position};
use super::{PrunableTree, RetentionFlags};
use crate::tree::tests::{leaf, nil, parent};
#[test]
fn root() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::EPHEMERAL)),
);
assert_eq!(
t.root_hash(Address::from_parts(Level::from(1), 0), Position::from(2)),
Ok("ab".to_string())
);
let t0 = parent(nil(), t.clone());
assert_eq!(
t0.root_hash(Address::from_parts(Level::from(2), 0), Position::from(4)),
Err(vec![Address::from_parts(Level::from(1), 0)])
);
// Check root computation with truncation
let t1 = parent(t, nil());
assert_eq!(
t1.root_hash(Address::from_parts(Level::from(2), 0), Position::from(2)),
Ok("ab__".to_string())
);
assert_eq!(
t1.root_hash(Address::from_parts(Level::from(2), 0), Position::from(3)),
Err(vec![Address::from_parts(Level::from(1), 1)])
);
}
#[test]
fn marked_positions() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::MARKED)),
);
assert_eq!(
t.marked_positions(Address::from_parts(Level::from(1), 0)),
BTreeSet::from([Position::from(1)])
);
let t0 = parent(t.clone(), t);
assert_eq!(
t0.marked_positions(Address::from_parts(Level::from(2), 1)),
BTreeSet::from([Position::from(5), Position::from(7)])
);
}
#[test]
fn prune() {
let t: PrunableTree<String> = parent(
leaf(("a".to_string(), RetentionFlags::EPHEMERAL)),
leaf(("b".to_string(), RetentionFlags::EPHEMERAL)),
);
assert_eq!(
t.clone().prune(Level::from(1)),
leaf(("ab".to_string(), RetentionFlags::EPHEMERAL))
);
let t0 = parent(leaf(("c".to_string(), RetentionFlags::MARKED)), t);
assert_eq!(
t0.prune(Level::from(2)),
parent(
leaf(("c".to_string(), RetentionFlags::MARKED)),
leaf(("ab".to_string(), RetentionFlags::EPHEMERAL))
)
);
}
#[test]
fn merge_checked() {
let t0: PrunableTree<String> =
parent(leaf(("a".to_string(), RetentionFlags::EPHEMERAL)), nil());
let t1: PrunableTree<String> =
parent(nil(), leaf(("b".to_string(), RetentionFlags::EPHEMERAL)));
assert_eq!(
t0.clone()
.merge_checked(Address::from_parts(1.into(), 0), t1.clone()),
Ok(leaf(("ab".to_string(), RetentionFlags::EPHEMERAL)))
);
let t2: PrunableTree<String> =
parent(leaf(("c".to_string(), RetentionFlags::EPHEMERAL)), nil());
assert_eq!(
t0.clone()
.merge_checked(Address::from_parts(1.into(), 0), t2.clone()),
Err(Address::from_parts(0.into(), 0))
);
let t3: PrunableTree<String> = parent(t0, t2);
let t4: PrunableTree<String> = parent(t1.clone(), t1);
assert_eq!(
t3.merge_checked(Address::from_parts(2.into(), 0), t4),
Ok(leaf(("abcb".to_string(), RetentionFlags::EPHEMERAL)))
);
}
}