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use crate::{
self as concordium_std, cmp::Ordering, marker::PhantomData, mem, prims, vec::Vec, Deletable,
Deserial, DeserialWithState, Get, HasStateApi, ParseResult, Read, Serial, Serialize, StateApi,
StateItemPrefix, StateMap, StateRef, StateRefMut, UnwrapAbort, Write, STATE_ITEM_PREFIX_SIZE,
};
/// An ordered map based on [B-Tree](https://en.wikipedia.org/wiki/B-tree), where
/// each node is stored separately in the low-level key-value store.
///
/// It can be seen as an extension adding tracking of the keys ordering on top
/// of [`StateMap`] to provide functions such as [`higher`](Self::higher) and
/// [`lower`](Self::lower). This results in some overhead when inserting and
/// deleting entries from the map compared to using [`StateMap`].
///
/// | Operation | Performance |
/// |-------------------------------------------------|---------------|
/// | [`get`](Self::get) / [`get_mut`](Self::get_mut) | O(k) |
/// | [`insert`](Self::insert) | O(k + log(n)) |
/// | [`remove`](Self::remove) | O(k + log(n)) |
/// | [`higher`](Self::higher)/[`lower`](Self::lower) | O(k + log(n)) |
///
/// Where `k` is the byte size of the serialized keys and `n` is the number of
/// entries in the map.
///
/// ## Type parameters
///
/// The map `StateBTreeMap<K, V, M>` is parametrized by the types:
/// - `K`: Keys used in the map. Most operations on the map require this to
/// implement [`Serialize`](crate::Serialize). Keys cannot contain references
/// to the low-level state, such as types containing
/// [`StateBox`](crate::StateBox), [`StateMap`](crate::StateMap) and
/// [`StateSet`](crate::StateSet).
/// - `V`: Values stored in the map. Most operations on the map require this to
/// implement [`Serial`](crate::Serial) and
/// [`DeserialWithState<StateApi>`](crate::DeserialWithState).
/// - `M`: A `const usize` determining the _minimum degree_ of the B-tree.
/// _Must_ be a value of `2` or above for the tree to work. This can be used
/// to tweak the height of the tree vs size of each node in the tree. The
/// default is set to 8, which seems to perform well on benchmarks. These
/// benchmarks ran operations on a collection of 1000 elements, some using
/// keys of 4 bytes others 16 bytes.
///
/// ## Usage
///
/// New maps can be constructed using the
/// [`new_btree_map`](crate::StateBuilder::new_btree_map) method on the
/// [`StateBuilder`](crate::StateBuilder).
///
/// ```no_run
/// # use concordium_std::*;
/// # let mut state_builder = StateBuilder::open(StateApi::open());
/// /// In an init method:
/// let mut map1 = state_builder.new_btree_map();
/// # map1.insert(0u8, 1u8); // Specifies type of map.
///
/// # let mut host = ExternHost { state: (), state_builder };
/// /// In a receive method:
/// let mut map2 = host.state_builder().new_btree_map();
/// # map2.insert(0u16, 1u16);
/// ```
///
/// ### **Caution**
///
/// `StateBTreeMap`s must be explicitly deleted when they are no longer needed,
/// otherwise they will remain in the contract's state, albeit unreachable.
///
/// ```no_run
/// # use concordium_std::*;
/// struct MyState {
/// inner: StateBTreeMap<u64, u64>,
/// }
/// fn incorrect_replace(state_builder: &mut StateBuilder, state: &mut MyState) {
/// // The following is incorrect. The old value of `inner` is not properly deleted.
/// // from the state.
/// state.inner = state_builder.new_btree_map(); // ⚠️
/// }
/// ```
/// Instead, either the map should be [cleared](StateBTreeMap::clear) or
/// explicitly deleted.
///
/// ```no_run
/// # use concordium_std::*;
/// # struct MyState {
/// # inner: StateBTreeMap<u64, u64>
/// # }
/// fn correct_replace(state_builder: &mut StateBuilder, state: &mut MyState) {
/// state.inner.clear_flat();
/// }
/// ```
/// Or alternatively
/// ```no_run
/// # use concordium_std::*;
/// # struct MyState {
/// # inner: StateBTreeMap<u64, u64>
/// # }
/// fn correct_replace(state_builder: &mut StateBuilder, state: &mut MyState) {
/// let old_map = mem::replace(&mut state.inner, state_builder.new_btree_map());
/// old_map.delete()
/// }
/// ```
#[derive(Serial)]
pub struct StateBTreeMap<K, V, const M: usize = 8> {
/// Mapping from key to value.
/// Each key in this map must also be in the `key_order` set.
pub(crate) key_value: StateMap<K, V, StateApi>,
/// A set for tracking the order of the inserted keys.
/// Each key in this set must also have an associated value in the
/// `key_value` map.
pub(crate) key_order: StateBTreeSet<K, M>,
}
impl<const M: usize, K, V> StateBTreeMap<K, V, M> {
/// Insert a key-value pair into the map.
/// Returns the previous value if the key was already in the map.
///
/// *Caution*: If `Option<V>` is to be deleted and contains a data structure
/// prefixed with `State` (such as [StateBox](crate::StateBox) or
/// [StateMap](crate::StateMap)), then it is important to call
/// [`Deletable::delete`](crate::Deletable::delete) on the value returned
/// when you're finished with it. Otherwise, it will remain in the
/// contract state.
#[must_use]
pub fn insert(&mut self, key: K, value: V) -> Option<V>
where
K: Serialize + Ord,
V: Serial + DeserialWithState<StateApi>, {
let old_value_option = self.key_value.insert_borrowed(&key, value);
if old_value_option.is_none() && !self.key_order.insert(key) {
// Inconsistency between the map and ordered_set.
crate::trap();
}
old_value_option
}
/// Remove a key from the map, returning the value at the key if the key was
/// previously in the map.
///
/// *Caution*: If `V` is a [StateBox](crate::StateBox),
/// [StateMap](crate::StateMap), then it is important to call
/// [`Deletable::delete`](crate::Deletable::delete) on the value returned
/// when you're finished with it. Otherwise, it will remain in the
/// contract state.
#[must_use]
pub fn remove_and_get(&mut self, key: &K) -> Option<V>
where
K: Serialize + Ord,
V: Serial + DeserialWithState<StateApi> + Deletable, {
let v = self.key_value.remove_and_get(key);
if v.is_some() && !self.key_order.remove(key) {
// Inconsistency between the map and ordered_set.
crate::trap();
}
v
}
/// Remove a key from the map.
/// This also deletes the value in the state.
pub fn remove(&mut self, key: &K)
where
K: Serialize + Ord,
V: Serial + DeserialWithState<StateApi> + Deletable, {
if self.key_order.remove(key) {
self.key_value.remove(key);
}
}
/// Get a reference to the value corresponding to the key.
pub fn get(&self, key: &K) -> Option<StateRef<V>>
where
K: Serialize,
V: Serial + DeserialWithState<StateApi>, {
// Minor optimization in the case of the empty collection. Since the length is
// tracked by the ordered set, we can return early, saving a key lookup.
if self.key_order.is_empty() {
None
} else {
self.key_value.get(key)
}
}
/// Get a mutable reference to the value corresponding to the key.
pub fn get_mut(&mut self, key: &K) -> Option<StateRefMut<V, StateApi>>
where
K: Serialize,
V: Serial + DeserialWithState<StateApi>, {
// Minor optimization in the case of the empty collection. Since the length is
// tracked by the ordered set, we can return early, saving a key lookup.
if self.key_order.is_empty() {
None
} else {
self.key_value.get_mut(key)
}
}
/// Returns `true` if the map contains a value for the specified key.
#[inline(always)]
pub fn contains_key(&self, key: &K) -> bool
where
K: Serialize + Ord, {
self.key_order.contains(key)
}
/// Returns the smallest key in the map that is strictly larger than the
/// provided key. `None` meaning no such key is present in the map.
#[inline(always)]
pub fn higher(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.higher(key)
}
/// Returns the smallest key in the map that is equal or larger than the
/// provided key. `None` meaning no such key is present in the map.
#[inline(always)]
pub fn eq_or_higher(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.eq_or_higher(key)
}
/// Returns the largest key in the map that is strictly smaller than the
/// provided key. `None` meaning no such key is present in the map.
#[inline(always)]
pub fn lower(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.lower(key)
}
/// Returns the largest key in the map that is equal or smaller than the
/// provided key. `None` meaning no such key is present in the map.
#[inline(always)]
pub fn eq_or_lower(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.eq_or_lower(key)
}
/// Returns a reference to the first key in the map, if any. This key is
/// always the minimum of all keys in the map.
#[inline(always)]
pub fn first_key(&self) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.first()
}
/// Returns a reference to the last key in the map, if any. This key is
/// always the maximum of all keys in the map.
#[inline(always)]
pub fn last_key(&self) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
self.key_order.last()
}
/// Return the number of elements in the map.
#[inline(always)]
pub fn len(&self) -> u32 { self.key_order.len() }
/// Returns `true` is the map contains no elements.
#[inline(always)]
pub fn is_empty(&self) -> bool { self.key_order.is_empty() }
/// Create an iterator over the entries of [`StateBTreeMap`].
/// Ordered by `K` ascending.
#[inline(always)]
pub fn iter(&self) -> StateBTreeMapIter<K, V, M> {
StateBTreeMapIter {
key_iter: self.key_order.iter(),
map: &self.key_value,
}
}
/// Clears the map, removing all key-value pairs.
/// This also includes values pointed at, if `V`, for example, is a
/// [StateBox](crate::StateBox). **If applicable use
/// [`clear_flat`](Self::clear_flat) instead.**
pub fn clear(&mut self)
where
K: Serialize,
V: Serial + DeserialWithState<StateApi> + Deletable, {
self.key_value.clear();
self.key_order.clear();
}
/// Clears the map, removing all key-value pairs.
/// **This should be used over [`clear`](Self::clear) if it is
/// applicable.** It avoids recursive deletion of values since the
/// values are required to be _flat_.
///
/// Unfortunately it is not possible to automatically choose between these
/// implementations. Once Rust gets trait specialization then this might
/// be possible.
pub fn clear_flat(&mut self)
where
K: Serialize,
V: Serialize, {
self.key_value.clear_flat();
self.key_order.clear();
}
}
/// An ordered set based on [B-Tree](https://en.wikipedia.org/wiki/B-tree), where
/// each node is stored separately in the low-level key-value store.
///
/// | Operation | Performance |
/// |-------------------------------------------------|---------------|
/// | [`contains`](Self::contains) | O(k + log(n)) |
/// | [`insert`](Self::insert) | O(k + log(n)) |
/// | [`remove`](Self::remove) | O(k + log(n)) |
/// | [`higher`](Self::higher)/[`lower`](Self::lower) | O(k + log(n)) |
///
/// Where `k` is the byte size of the serialized keys and `n` is the number of
/// entries in the map.
///
/// ## Type parameters
///
/// The map `StateBTreeSet<K, M>` is parametrized by the types:
/// - `K`: Keys used in the set. Most operations on the set require this to
/// implement [`Serialize`](crate::Serialize). Keys cannot contain references
/// to the low-level state, such as types containing
/// [`StateBox`](crate::StateBox), [`StateMap`](crate::StateMap) and
/// [`StateSet`](crate::StateSet).
/// - `M`: A `const usize` determining the _minimum degree_ of the B-tree.
/// _Must_ be a value of `2` or above for the tree to work. This can be used
/// to tweak the height of the tree vs size of each node in the tree. The
/// default is set to 8, which seems to perform well on benchmarks. These
/// benchmarks ran operations on a collection of 1000 elements, some using
/// keys of 4 bytes others 16 bytes.
///
/// ## Usage
///
/// New sets can be constructed using the
/// [`new_btree_set`](crate::StateBuilder::new_btree_set) method on the
/// [`StateBuilder`](crate::StateBuilder).
///
/// ```no_run
/// # use concordium_std::*;
/// # let mut state_builder = StateBuilder::open(StateApi::open());
/// /// In an init method:
/// let mut map1 = state_builder.new_btree_set();
/// # map1.insert(0u8); // Specifies type of map.
/// # let mut host = ExternHost { state: (), state_builder };
/// /// In a receive method:
/// let mut map2 = host.state_builder().new_btree_set();
/// # map2.insert(0u16);
/// ```
///
/// ### **Caution**
///
/// `StateBTreeSet`s must be explicitly deleted when they are no longer needed,
/// otherwise they will remain in the contract's state, albeit unreachable.
///
/// ```no_run
/// # use concordium_std::*;
/// struct MyState {
/// inner: StateBTreeSet<u64>,
/// }
/// fn incorrect_replace(state_builder: &mut StateBuilder, state: &mut MyState) {
/// // The following is incorrect. The old value of `inner` is not properly deleted.
/// // from the state.
/// state.inner = state_builder.new_btree_set(); // ⚠️
/// }
/// ```
/// Instead, the set should be [cleared](StateBTreeSet::clear):
///
/// ```no_run
/// # use concordium_std::*;
/// # struct MyState {
/// # inner: StateBTreeSet<u64>
/// # }
/// fn correct_replace(state_builder: &mut StateBuilder, state: &mut MyState) {
/// state.inner.clear();
/// }
/// ```
pub struct StateBTreeSet<K, const M: usize = 8> {
/// Type marker for the key.
_marker_key: PhantomData<K>,
/// The unique prefix to use for this map in the key-value store.
prefix: StateItemPrefix,
/// The API for interacting with the low-level state.
state_api: StateApi,
/// The ID of the root node of the tree, where None represents the tree is
/// empty.
root: Option<NodeId>,
/// Tracking the number of items in the tree.
len: u32,
/// Tracking the next available ID for a new node.
next_node_id: NodeId,
}
impl<const M: usize, K> StateBTreeSet<K, M> {
/// Construct a new [`StateBTreeSet`] given a unique prefix to use in the
/// key-value store.
pub(crate) fn new(state_api: StateApi, prefix: StateItemPrefix) -> Self {
Self {
_marker_key: Default::default(),
prefix,
state_api,
root: None,
len: 0,
next_node_id: NodeId {
id: 0,
},
}
}
/// Insert a key into the set.
/// Returns true if the key is new in the collection.
pub fn insert(&mut self, key: K) -> bool
where
K: Serialize + Ord, {
let Some(root_id) = self.root else {
let (node_id, _) = self.create_node(crate::vec![key], Vec::new());
self.root = Some(node_id);
self.len = 1;
return true;
};
let root_node = self.get_node_mut(root_id);
if !root_node.is_full() {
let new = self.insert_non_full(root_node, key);
if new {
self.len += 1;
}
return new;
} else if root_node.keys.binary_search(&key).is_ok() {
return false;
}
// The root node is full, so we construct a new root node.
let (new_root_id, mut new_root) = self.create_node(Vec::new(), crate::vec![root_id]);
self.root = Some(new_root_id);
// The old root node is now a child node.
let mut child = root_node;
let new_larger_child = self.split_child(&mut new_root, 0, &mut child);
// new_root now contains one key and two children, so we need to know
// which one to insert into.
let key_in_root = unsafe { new_root.keys.get_unchecked(0) };
let child = if key_in_root < &key {
new_larger_child
} else {
child
};
let new = self.insert_non_full(child, key);
if new {
self.len += 1;
}
new
}
/// Returns `true` if the set contains an element equal to the key.
pub fn contains(&self, key: &K) -> bool
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return false;
};
let mut node = self.get_node(root_node_id);
loop {
let Err(child_index) = node.keys.binary_search(key) else {
return true;
};
if node.is_leaf() {
return false;
}
let child_node_id = unsafe { *node.children.get_unchecked(child_index) };
node = self.get_node(child_node_id);
}
}
/// Return the number of elements in the set.
pub fn len(&self) -> u32 { self.len }
/// Returns `true` is the set contains no elements.
pub fn is_empty(&self) -> bool { self.root.is_none() }
/// Get an iterator over the elements in the `StateBTreeSet`. The iterator
/// returns elements in increasing order.
pub fn iter(&self) -> StateBTreeSetIter<K, M> {
StateBTreeSetIter {
length: self.len.try_into().unwrap_abort(),
next_node: self.root,
depth_first_stack: Vec::new(),
tree: self,
_marker_lifetime: Default::default(),
}
}
/// Clears the set, removing all elements.
pub fn clear(&mut self) {
// Reset the information.
self.root = None;
self.next_node_id = NodeId {
id: 0,
};
self.len = 0;
// Then delete every node store in the state.
// Unwrapping is safe when only using the high-level API.
self.state_api.delete_prefix(&self.prefix).unwrap_abort();
}
/// Returns the smallest key in the set that is strictly larger than the
/// provided key. `None` meaning no such key is present in the set.
pub fn higher(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut node = self.get_node(root_node_id);
let mut higher_so_far = None;
loop {
let higher_key_index = match node.keys.binary_search(key) {
Ok(index) => index + 1,
Err(index) => index,
};
if node.is_leaf() {
return if higher_key_index < node.keys.len() {
// This does not mutate the node in the end, just the representation in memory
// which is freed after the call.
Some(StateRef::new(node.keys.swap_remove(higher_key_index)))
} else {
higher_so_far
};
} else {
if higher_key_index < node.keys.len() {
// This does not mutate the node in the end, just the representation in memory
// which is freed after the call.
higher_so_far = Some(StateRef::new(node.keys.swap_remove(higher_key_index)))
}
let child_node_id = unsafe { *node.children.get_unchecked(higher_key_index) };
node = self.get_node(child_node_id);
}
}
}
/// Returns the smallest key in the set that is equal or larger than the
/// provided key. `None` meaning no such key is present in the set.
pub fn eq_or_higher(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut node = self.get_node(root_node_id);
let mut higher_so_far = None;
loop {
let higher_key_index = match node.keys.binary_search(key) {
Ok(index) => {
// This does not mutate the node in the end, just the representation in memory
// which is freed after the call.
return Some(StateRef::new(node.keys.swap_remove(index)));
}
Err(index) => index,
};
if node.is_leaf() {
return if higher_key_index < node.keys.len() {
Some(StateRef::new(node.keys.swap_remove(higher_key_index)))
} else {
higher_so_far
};
} else {
if higher_key_index < node.keys.len() {
higher_so_far = Some(StateRef::new(node.keys.swap_remove(higher_key_index)))
}
let child_node_id = unsafe { *node.children.get_unchecked(higher_key_index) };
node = self.get_node(child_node_id);
}
}
}
/// Returns the largest key in the set that is strictly smaller than the
/// provided key. `None` meaning no such key is present in the set.
pub fn lower(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut node = self.get_node(root_node_id);
let mut lower_so_far = None;
loop {
let lower_key_index = match node.keys.binary_search(key) {
Ok(index) => index,
Err(index) => index,
};
if node.is_leaf() {
return if lower_key_index == 0 {
lower_so_far
} else {
Some(StateRef::new(node.keys.swap_remove(lower_key_index - 1)))
};
} else {
if lower_key_index > 0 {
lower_so_far = Some(StateRef::new(node.keys.swap_remove(lower_key_index - 1)));
}
let child_node_id = unsafe { node.children.get_unchecked(lower_key_index) };
node = self.get_node(*child_node_id)
}
}
}
/// Returns the largest key in the set that is equal or smaller than the
/// provided key. `None` meaning no such key is present in the set.
pub fn eq_or_lower(&self, key: &K) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut node = self.get_node(root_node_id);
let mut lower_so_far = None;
loop {
let lower_key_index = match node.keys.binary_search(key) {
Ok(index) => {
// This does not mutate the node in the end, just the representation in memory
// which is freed after the call.
return Some(StateRef::new(node.keys.swap_remove(index)));
}
Err(index) => index,
};
if node.is_leaf() {
return if lower_key_index == 0 {
lower_so_far
} else {
Some(StateRef::new(node.keys.swap_remove(lower_key_index - 1)))
};
} else {
if lower_key_index > 0 {
lower_so_far = Some(StateRef::new(node.keys.swap_remove(lower_key_index - 1)));
}
let child_node_id = unsafe { node.children.get_unchecked(lower_key_index) };
node = self.get_node(*child_node_id)
}
}
}
/// Returns a reference to the first key in the set, if any. This key is
/// always the minimum of all keys in the set.
pub fn first(&self) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut root = self.get_node(root_node_id);
if root.is_leaf() {
Some(StateRef::new(root.keys.swap_remove(0)))
} else {
Some(StateRef::new(self.get_lowest_key(&root, 0)))
}
}
/// Returns a reference to the last key in the set, if any. This key is
/// always the maximum of all keys in the set.
pub fn last(&self) -> Option<StateRef<K>>
where
K: Serialize + Ord, {
let Some(root_node_id) = self.root else {
return None;
};
let mut root = self.get_node(root_node_id);
if root.is_leaf() {
Some(StateRef::new(root.keys.pop().unwrap_abort()))
} else {
Some(StateRef::new(self.get_highest_key(&root, root.children.len() - 1)))
}
}
/// Remove a key from the set.
/// Returns whether such an element was present.
pub fn remove(&mut self, key: &K) -> bool
where
K: Ord + Serialize, {
let Some(root_node_id) = self.root else {
return false;
};
let deleted_something = {
let mut node = self.get_node_mut(root_node_id);
loop {
match node.keys.binary_search(key) {
Ok(index) => {
if node.is_leaf() {
// Found the key in this node and the node is a leaf, meaning we
// simply remove it.
// This will not violate the minimum keys invariant, since a node
// ensures a child can spare a key before iteration and the root
// node is not part of the
// invariant.
node.keys.remove(index);
break true;
}
// Found the key in this node, but the node is not a leaf.
let mut left_child = self.get_node_mut(node.children[index]);
if !left_child.is_at_min() {
// If the child with smaller keys can spare a key, we take the
// highest key from it.
node.keys[index] = self.remove_largest_key(left_child);
break true;
}
let right_child = self.get_node_mut(node.children[index + 1]);
if !right_child.is_at_min() {
// If the child with larger keys can spare a key, we take the lowest
// key from it.
node.keys[index] = self.remove_smallest_key(right_child);
break true;
}
// No child on either side of the key can spare a key at this point, so
// we merge them into one child, moving the
// key into the merged child and try
// to remove from this.
self.merge(&mut node, index, &mut left_child, right_child);
node = left_child;
continue;
}
Err(index) => {
// Node did not contain the key.
if node.is_leaf() {
break false;
}
// Node did not contain the key and is not a leaf.
// Check and proactively prepare the child to be able to delete a key.
node = self.prepare_child_for_key_removal(node, index);
}
};
}
};
// If something was deleted, we update the length and make sure to remove the
// root node if needed.
let root = self.get_node_mut(root_node_id);
if deleted_something {
self.len -= 1;
if self.len == 0 {
// Remote the root node if tree is empty.
self.root = None;
self.delete_node(root_node_id, root);
return true;
}
}
// If the root is empty but the tree is not, point to the only child of the root
// as the root.
if root.keys.is_empty() {
self.root = Some(root.children[0]);
self.delete_node(root_node_id, root);
}
deleted_something
}
/// Internal function for taking the largest key in a subtree.
///
/// Assumes:
/// - The provided node is not the root.
/// - The node contain more than minimum number of keys.
fn remove_largest_key(&mut self, mut node: StateRefMut<'_, Node<M, K>, StateApi>) -> K
where
K: Ord + Serialize, {
while !node.is_leaf() {
// Node is not a leaf, so we move further down this subtree.
let child_index = node.children.len() - 1;
node = self.prepare_child_for_key_removal(node, child_index);
}
// The node is a leaf, meaning we simply remove it.
// This will not violate the minimum keys invariant, since a node
// ensures a child can spare a key before iteration.
node.keys.pop().unwrap_abort()
}
/// Internal function for taking the smallest key in a subtree.
///
/// Assumes:
/// - The provided node is not the root.
/// - The provided `node` contain more than minimum number of keys.
fn remove_smallest_key(&mut self, mut node: StateRefMut<'_, Node<M, K>, StateApi>) -> K
where
K: Ord + Serialize, {
while !node.is_leaf() {
// Node is not a leaf, so we move further down this subtree.
let child_index = 0;
node = self.prepare_child_for_key_removal(node, child_index);
}
// The node is a leaf, meaning we simply remove it.
// This will not violate the minimum keys invariant, since a node
// ensures a child can spare a key before iteration.
node.keys.remove(0)
}
/// Internal function for key rotation, preparing a node for deleting a key.
/// Returns the now prepared child at `index`.
/// Assumes:
/// - The provided `node` is not a leaf and has a child at `index`.
/// - The minimum degree `M` is at least 2 or more.
fn prepare_child_for_key_removal<'c>(
&mut self,
mut node: StateRefMut<Node<M, K>, StateApi>,
index: usize,
) -> StateRefMut<'c, Node<M, K>, StateApi>
where
K: Ord + Serialize, {
let mut child = self.get_node_mut(node.children[index]);
if !child.is_at_min() {
return child;
}
// The child is at minimum keys, so first attempt to take a key from either
// sibling, otherwise merge with one of them.
let has_smaller_sibling = 0 < index;
let has_larger_sibling = index < node.children.len() - 1;
let smaller_sibling = if has_smaller_sibling {
let mut smaller_sibling = self.get_node_mut(node.children[index - 1]);
if !smaller_sibling.is_at_min() {
// The smaller sibling can spare a key, so we replace the largest
// key from the sibling, put it in
// the parent and take a key from
// the parent.
let largest_key_sibling = smaller_sibling.keys.pop().unwrap_abort();
let swapped_node_key = mem::replace(&mut node.keys[index - 1], largest_key_sibling);
child.keys.insert(0, swapped_node_key);
if !child.is_leaf() {
child.children.insert(0, smaller_sibling.children.pop().unwrap_abort());
}
return child;
}
Some(smaller_sibling)
} else {
None
};
let larger_sibling = if has_larger_sibling {
let mut larger_sibling = self.get_node_mut(node.children[index + 1]);
if !larger_sibling.is_at_min() {
// The larger sibling can spare a key, so we replace the smallest
// key from the sibling, put it in
// the parent and take a key from
// the parent.
let first_key_sibling = larger_sibling.keys.remove(0);
let swapped_node_key = mem::replace(&mut node.keys[index], first_key_sibling);
child.keys.push(swapped_node_key);
if !child.is_leaf() {
child.children.push(larger_sibling.children.remove(0));
}
return child;
}
Some(larger_sibling)
} else {
None
};
if let Some(sibling) = larger_sibling {
self.merge(&mut node, index, &mut child, sibling);
child
} else if let Some(mut sibling) = smaller_sibling {
self.merge(&mut node, index - 1, &mut sibling, child);
sibling
} else {
// Unreachable code, since M must be 2 or larger (the minimum degree), a
// child node must have at least one sibling.
crate::trap();
}
}
/// Internal function for getting the highest key in a subtree.
/// Assumes the provided `node` is not a leaf and has a child at
/// `child_index`.
fn get_highest_key(&self, node: &Node<M, K>, child_index: usize) -> K
where
K: Ord + Serialize, {
let mut node = self.get_node(node.children[child_index]);
while !node.is_leaf() {
let child_node_id = node.children.last().unwrap_abort();
node = self.get_node(*child_node_id);
}
// This does not mutate the node in the end, just the representation in memory
// which is freed after the call.
node.keys.pop().unwrap_abort()
}
/// Internal function for getting the lowest key in a subtree.
/// Assumes the provided `node` is not a leaf and has a child at
/// `child_index`.
fn get_lowest_key(&self, node: &Node<M, K>, child_index: usize) -> K
where
K: Ord + Serialize, {
let mut node = self.get_node(node.children[child_index]);
while !node.is_leaf() {
let child_node_id = node.children.first().unwrap_abort();
node = self.get_node(*child_node_id);
}
node.keys.swap_remove(0)
}
/// Move key at `index` from the node to the lower child and then merges
/// this child with the content of its larger sibling, deleting the sibling.
///
/// Assumes:
/// - `parent_node` has children `child` at `index` and `larger_child` at
/// `index + 1`.
/// - Both children are at minimum number of keys (`M - 1`).
fn merge(
&mut self,
parent_node: &mut Node<M, K>,
index: usize,
child: &mut Node<M, K>,
mut larger_child: StateRefMut<Node<M, K>, StateApi>,
) where
K: Ord + Serialize, {
let parent_key = parent_node.keys.remove(index);
let larger_child_id = parent_node.children.remove(index + 1);
child.keys.push(parent_key);
child.keys.append(&mut larger_child.keys);
child.children.append(&mut larger_child.children);
self.delete_node(larger_child_id, larger_child);
}
/// Internal function for constructing a node. It will increment the next
/// node ID and create an entry in the smart contract key-value store.
fn create_node<'b>(
&mut self,
keys: Vec<K>,
children: Vec<NodeId>,
) -> (NodeId, StateRefMut<'b, Node<M, K>, StateApi>)
where
K: Serialize, {
let node_id = self.next_node_id.fetch_and_add();
let node = Node {
keys,
children,
};
let entry = self.state_api.create_entry(&node_id.as_key(&self.prefix)).unwrap_abort();
let mut ref_mut: StateRefMut<'_, Node<M, K>, StateApi> =
StateRefMut::new(entry, self.state_api.clone());
ref_mut.set(node);
(node_id, ref_mut)
}
/// Internal function for deleting a node, removing the entry in the smart
/// contract key-value store. Traps if no node was present.
fn delete_node(&mut self, node_id: NodeId, node: StateRefMut<Node<M, K>, StateApi>)
where
K: Serial, {
let key = node_id.as_key(&self.prefix);
node.drop_without_storing();
unsafe { prims::state_delete_entry(key.as_ptr(), key.len() as u32) };
}
/// Internal function for inserting into a subtree.
/// Assumes the given node is not full.
fn insert_non_full(&mut self, initial_node: StateRefMut<Node<M, K>, StateApi>, key: K) -> bool
where
K: Serialize + Ord, {
let mut node = initial_node;
loop {
let Err(insert_index) = node.keys.binary_search(&key) else {
// We find the key in this node, so we do nothing.
return false;
};
// The key is not in this node.
if node.is_leaf() {
// Since we can assume the node is not full and this is a leaf, we can just
// insert here.
node.keys.insert(insert_index, key);
return true;
}
// The node is not a leaf, so we want to insert in the relevant child node.
let child_id = unsafe { node.children.get_unchecked(insert_index) };
let mut child = self.get_node_mut(*child_id);
node = if !child.is_full() {
child
} else {
let larger_child = self.split_child(&mut node, insert_index, &mut child);
// Since the child is now split into two, we have to check which one to insert
// into.
let moved_up_key = &node.keys[insert_index];
match moved_up_key.cmp(&key) {
Ordering::Equal => return false,
Ordering::Less => larger_child,
Ordering::Greater => child,
}
};
}
}
/// Internal function for splitting the child node at a given index for a
/// given node. This will also mutate the given node adding a new key
/// and child after the provided child_index.
/// Returns the newly created node.
///
/// Assumes:
/// - Node is not a leaf and has `child` as child at `child_index`.
/// - `child` is at maximum keys (`2 * M - 1`).
fn split_child<'b>(
&mut self,
node: &mut Node<M, K>,
child_index: usize,
child: &mut Node<M, K>,
) -> StateRefMut<'b, Node<M, K>, StateApi>
where
K: Serialize + Ord, {
let split_index = Node::<M, K>::MINIMUM_KEY_LEN + 1;
let (new_larger_sibling_id, new_larger_sibling) = self.create_node(
child.keys.split_off(split_index),
if child.is_leaf() {
Vec::new()
} else {
child.children.split_off(split_index)
},
);
let key = child.keys.pop().unwrap_abort();
node.children.insert(child_index + 1, new_larger_sibling_id);
node.keys.insert(child_index, key);
new_larger_sibling
}
/// Internal function for looking up a node in the tree.
/// This assumes the node is present and traps if this is not the case.
fn get_node<Key>(&self, node_id: NodeId) -> Node<M, Key>
where
Key: Deserial, {
let key = node_id.as_key(&self.prefix);
let mut entry = self.state_api.lookup_entry(&key).unwrap_abort();
entry.get().unwrap_abort()
}
/// Internal function for looking up a node, providing mutable access.
/// This assumes the node is present and traps if this is not the case.
fn get_node_mut<'b>(&mut self, node_id: NodeId) -> StateRefMut<'b, Node<M, K>, StateApi>
where
K: Serial, {
let key = node_id.as_key(&self.prefix);
let entry = self.state_api.lookup_entry(&key).unwrap_abort();
StateRefMut::new(entry, self.state_api.clone())
}
}
/// An iterator over the entries of a [`StateBTreeSet`].
///
/// Ordered by `K`.
///
/// This `struct` is created by the [`iter`][StateBTreeSet::iter] method on
/// [`StateBTreeSet`]. See its documentation for more.
pub struct StateBTreeSetIter<'a, 'b, K, const M: usize> {
/// The number of elements left to iterate.
length: usize,
/// Reference to a node in the tree to load and iterate before the current
/// node.
next_node: Option<NodeId>,
/// Tracking the nodes depth first, which are currently being iterated.
depth_first_stack: Vec<(Node<M, KeyWrapper<K>>, usize)>,
/// Reference to the set, needed for looking up the nodes.
tree: &'a StateBTreeSet<K, M>,
/// Marker for tracking the lifetime of the key.
_marker_lifetime: PhantomData<&'b K>,
}
impl<'a, 'b, const M: usize, K> Iterator for StateBTreeSetIter<'a, 'b, K, M>
where
'a: 'b,
K: Deserial,
{
type Item = StateRef<'b, K>;
fn next(&mut self) -> Option<Self::Item> {
while let Some(id) = self.next_node.take() {
let node = self.tree.get_node(id);
if !node.is_leaf() {
self.next_node = Some(node.children[0]);
}
self.depth_first_stack.push((node, 0));
}
let (node, index) = self.depth_first_stack.last_mut()?;
let key = node.keys[*index].key.take().unwrap_abort();
*index += 1;
let no_more_keys = index == &node.keys.len();
if !node.is_leaf() {
let child_id = node.children[*index];
self.next_node = Some(child_id);
}
if no_more_keys {
// This was the last key in the node, so remove the node from the stack.
let _ = self.depth_first_stack.pop();
}
self.length -= 1;
Some(StateRef::new(key))
}
fn size_hint(&self) -> (usize, Option<usize>) { (self.length, Some(self.length)) }
}
/// An iterator over the entries of a [`StateBTreeMap`].
///
/// Ordered by `K`.
///
/// This `struct` is created by the [`iter`][StateBTreeMap::iter] method on
/// [`StateBTreeMap`]. See its documentation for more.
pub struct StateBTreeMapIter<'a, 'b, K, V, const M: usize> {
/// Iterator over the keys in the map.
key_iter: StateBTreeSetIter<'a, 'b, K, M>,
/// Reference to the map holding the values.
map: &'a StateMap<K, V, StateApi>,
}
impl<'a, 'b, const M: usize, K, V> Iterator for StateBTreeMapIter<'a, 'b, K, V, M>
where
'a: 'b,
K: Serialize,
V: Serial + DeserialWithState<StateApi> + 'b,
{
type Item = (StateRef<'b, K>, StateRef<'b, V>);
fn next(&mut self) -> Option<Self::Item> {
let next_key = self.key_iter.next()?;
let value = self.map.get(&next_key).unwrap_abort();
// Unwrap is safe, otherwise the map and the set have inconsistencies.
Some((next_key, value))
}
fn size_hint(&self) -> (usize, Option<usize>) { self.key_iter.size_hint() }
}
/// Identifier for a node in the tree. Used to construct the key, where this
/// node is stored in the smart contract key-value store.
#[derive(Debug, Copy, Clone, Serialize)]
#[repr(transparent)]
struct NodeId {
id: u64,
}
/// Byte size of the key used to store a BTree internal node in the smart
/// contract key-value store.
const BTREE_NODE_KEY_SIZE: usize = STATE_ITEM_PREFIX_SIZE + NodeId::SERIALIZED_BYTE_SIZE;
impl NodeId {
/// Byte size of `NodeId` when serialized.
const SERIALIZED_BYTE_SIZE: usize = 8;
/// Return a copy of the NodeId, then increments itself.
fn fetch_and_add(&mut self) -> Self {
let current = *self;
self.id += 1;
current
}
/// Construct the key for the node in the key-value store from the node ID.
fn as_key(&self, prefix: &StateItemPrefix) -> [u8; BTREE_NODE_KEY_SIZE] {
// Create an uninitialized array of `MaybeUninit`. The `assume_init` is
// safe because the type we are claiming to have initialized here is a
// bunch of `MaybeUninit`s, which do not require initialization.
let mut prefixed: [mem::MaybeUninit<u8>; BTREE_NODE_KEY_SIZE] =
unsafe { mem::MaybeUninit::uninit().assume_init() };
for (place, value) in prefixed.iter_mut().zip(prefix) {
place.write(*value);
}
let id_bytes = self.id.to_le_bytes();
for (place, value) in prefixed[STATE_ITEM_PREFIX_SIZE..].iter_mut().zip(id_bytes) {
place.write(value);
}
// Transmuting away the maybeuninit is safe since we have initialized all of
// them.
unsafe { mem::transmute(prefixed) }
}
}
/// Type representing a node in the [`StateBTreeMap`].
/// Each node is stored separately in the smart contract key-value store.
#[derive(Debug, Serialize)]
struct Node<const M: usize, K> {
/// List of sorted keys tracked by this node.
/// This list should never be empty and contain between `M - 1` and `2M
/// - 1` elements. The root node being the only exception to this.
keys: Vec<K>,
/// List of nodes which are children of this node in the tree.
///
/// This list is empty when this node is representing a leaf.
/// When not a leaf, it will contain exactly `keys.len() + 1` elements.
///
/// The elements are ordered such that for a key `keys[i]`:
/// - `children[i]` is a subtree containing strictly smaller keys.
/// - `children[i + 1]` is a subtree containing strictly larger keys.
children: Vec<NodeId>,
}
impl<const M: usize, K> Node<M, K> {
/// The max length of the child list.
const MAXIMUM_CHILD_LEN: usize = 2 * M;
/// The max length of the key list.
const MAXIMUM_KEY_LEN: usize = Self::MAXIMUM_CHILD_LEN - 1;
/// The min length of the child list, when the node is not a leaf node.
const MINIMUM_CHILD_LEN: usize = M;
/// The min length of the key list, except when the node is root.
const MINIMUM_KEY_LEN: usize = Self::MINIMUM_CHILD_LEN - 1;
/// Check if the node holds the maximum number of keys.
#[inline(always)]
fn is_full(&self) -> bool { self.keys.len() == Self::MAXIMUM_KEY_LEN }
/// Check if the node is representing a leaf in the tree.
#[inline(always)]
fn is_leaf(&self) -> bool { self.children.is_empty() }
/// Check if the node holds the minimum number of keys.
#[inline(always)]
fn is_at_min(&self) -> bool { self.keys.len() == Self::MINIMUM_KEY_LEN }
}
/// Wrapper implement the exact same deserial as K, but wraps it in an
/// option in memory. This is used to allow taking a key from a mutable
/// reference to a node, without cloning the key, during iteration of the
/// set.
#[repr(transparent)]
struct KeyWrapper<K> {
key: Option<K>,
}
impl<K: Deserial> Deserial for KeyWrapper<K> {
fn deserial<R: Read>(source: &mut R) -> ParseResult<Self> {
let key = K::deserial(source)?;
Ok(Self {
key: Some(key),
})
}
}
impl<const M: usize, K> Serial for StateBTreeSet<K, M> {
fn serial<W: Write>(&self, out: &mut W) -> Result<(), W::Err> {
self.prefix.serial(out)?;
self.root.serial(out)?;
self.len.serial(out)?;
self.next_node_id.serial(out)
}
}
impl<const M: usize, K> DeserialWithState<StateApi> for StateBTreeSet<K, M> {
fn deserial_with_state<R: Read>(state: &StateApi, source: &mut R) -> ParseResult<Self> {
let prefix = source.get()?;
let root = source.get()?;
let len = source.get()?;
let next_node_id = source.get()?;
Ok(Self {
_marker_key: Default::default(),
prefix,
state_api: state.clone(),
root,
len,
next_node_id,
})
}
}
impl<const M: usize, K, V> DeserialWithState<StateApi> for StateBTreeMap<K, V, M> {
fn deserial_with_state<R: Read>(state: &StateApi, source: &mut R) -> ParseResult<Self> {
let key_value = StateMap::deserial_with_state(state, source)?;
let key_order = StateBTreeSet::deserial_with_state(state, source)?;
Ok(Self {
key_value,
key_order,
})
}
}
impl<const M: usize, K, V> Deletable for StateBTreeMap<K, V, M>
where
K: Serialize,
V: Serial + DeserialWithState<StateApi> + Deletable,
{
fn delete(mut self) { self.clear(); }
}
/// This test module relies on the runtime providing host functions and can only
/// be run using `cargo concordium test`.
#[cfg(feature = "internal-wasm-test")]
mod wasm_test_btree {
use super::*;
use crate::{claim, claim_eq, concordium_test, StateApi, StateBuilder};
/// The invariants to check in a btree.
/// Should only be used while debugging and testing the btree itself.
#[derive(Debug)]
pub(crate) enum InvariantViolation {
/// The collection has length above 0, but no root.
NonZeroLenWithNoRoot,
/// The collection contain a root node, but this has no keys.
ZeroKeysInRoot,
/// Iterating the keys in the entire collection, is not in strictly
/// ascending order.
IterationOutOfOrder,
/// Leaf node found at different depths.
LeafAtDifferentDepth,
/// The keys in a node are not in strictly ascending order.
NodeKeysOutOfOrder,
/// The non-leaf node does not contain `keys.len() + 1` children.
MismatchingChildrenLenKeyLen,
/// The non-root node contains fewer keys than the minimum.
KeysLenBelowMin,
/// The non-root node contains more keys than the maximum.
KeysLenAboveMax,
/// The leaf node contains children nodes.
LeafWithChildren,
/// The non-root non-leaf node contains fewer children than the minimum.
ChildrenLenBelowMin,
/// The non-root non-leaf node contains more children than the maximum.
ChildrenLenAboveMax,
}
impl<K, const M: usize> StateBTreeSet<K, M> {
/// Check invariants, producing an error if any of them are
/// violated.
/// See [`InvariantViolation`] for the of list invariants being checked.
/// Should only be used while debugging and testing the btree itself.
fn check_invariants(&self) -> Result<(), InvariantViolation>
where
K: Serialize + Ord, {
use crate::ops::Deref;
let Some(root_node_id) = self.root else {
return if self.len == 0 {
Ok(())
} else {
Err(InvariantViolation::NonZeroLenWithNoRoot)
};
};
let root: Node<M, K> = self.get_node(root_node_id);
if root.keys.is_empty() {
return Err(InvariantViolation::ZeroKeysInRoot);
}
for i in 1..root.keys.len() {
if &root.keys[i - 1] >= &root.keys[i] {
return Err(InvariantViolation::NodeKeysOutOfOrder);
}
}
if root.keys.len() > Node::<M, K>::MAXIMUM_KEY_LEN {
return Err(InvariantViolation::KeysLenAboveMax);
}
if root.is_leaf() {
if !root.children.is_empty() {
return Err(InvariantViolation::LeafWithChildren);
}
} else {
if root.children.len() != root.keys.len() + 1 {
return Err(InvariantViolation::MismatchingChildrenLenKeyLen);
}
if root.children.len() > Node::<M, K>::MAXIMUM_CHILD_LEN {
return Err(InvariantViolation::ChildrenLenAboveMax);
}
}
let mut stack = vec![(0usize, root.children)];
let mut leaf_depth = None;
while let Some((node_level, mut nodes)) = stack.pop() {
while let Some(node_id) = nodes.pop() {
let node: Node<M, K> = self.get_node(node_id);
node.check_invariants()?;
if node.is_leaf() {
let depth = leaf_depth.get_or_insert(node_level);
if *depth != node_level {
return Err(InvariantViolation::LeafAtDifferentDepth);
}
} else {
stack.push((node_level + 1, node.children));
}
}
}
let mut prev = None;
for key in self.iter() {
if let Some(p) = prev.as_deref() {
if p > key.deref() {
return Err(InvariantViolation::IterationOutOfOrder);
}
}
prev = Some(key);
}
Ok(())
}
/// Construct a string for displaying the btree and debug information.
/// Should only be used while debugging and testing the btree itself.
pub(crate) fn debug(&self) -> String
where
K: Serialize + std::fmt::Debug + Ord, {
let Some(root_node_id) = self.root else {
return format!("no root");
};
let mut string = String::new();
let root: Node<M, K> = self.get_node(root_node_id);
string.push_str(format!("root: {:#?}", root).as_str());
let mut stack = root.children;
while let Some(node_id) = stack.pop() {
let node: Node<M, K> = self.get_node(node_id);
string.push_str(
format!("node {} {:?}: {:#?},\n", node_id.id, node.check_invariants(), node)
.as_str(),
);
stack.extend(node.children);
}
string
}
}
impl<const M: usize, K> Node<M, K> {
/// Check invariants of a non-root node in a btree, producing an error
/// if any of them are violated.
/// See [`InvariantViolation`] for the of list invariants being checked.
/// Should only be used while debugging and testing the btree itself.
pub(crate) fn check_invariants(&self) -> Result<(), InvariantViolation>
where
K: Ord, {
for i in 1..self.keys.len() {
if &self.keys[i - 1] >= &self.keys[i] {
return Err(InvariantViolation::NodeKeysOutOfOrder);
}
}
if self.keys.len() < Self::MINIMUM_KEY_LEN {
return Err(InvariantViolation::KeysLenBelowMin);
}
if self.keys.len() > Self::MAXIMUM_KEY_LEN {
return Err(InvariantViolation::KeysLenAboveMax);
}
if self.is_leaf() {
if !self.children.is_empty() {
return Err(InvariantViolation::LeafWithChildren);
}
} else {
if self.children.len() != self.keys.len() + 1 {
return Err(InvariantViolation::MismatchingChildrenLenKeyLen);
}
if self.children.len() < Self::MINIMUM_CHILD_LEN {
return Err(InvariantViolation::ChildrenLenBelowMin);
}
if self.children.len() > Self::MAXIMUM_CHILD_LEN {
return Err(InvariantViolation::ChildrenLenAboveMax);
}
}
Ok(())
}
}
/// Insert `2 * M` items such that the btree contains more than the root
/// node. Checking that every item is contained in the collection.
#[concordium_test]
fn test_btree_insert_asc_above_max_branching_degree() {
let mut state_builder = StateBuilder::open(StateApi::open());
const M: usize = 5;
let mut tree = state_builder.new_btree_set_degree::<M, _>();
let items = (2 * M) as u32;
for n in 0..items {
claim!(tree.insert(n));
}
for n in 0..items {
claim!(tree.contains(&n));
}
claim_eq!(tree.len(), items)
}
/// Insert items such that the btree must be at least height 3 to contain
/// all of them. With a minimum degree of 2, each node can contain up to
/// 3 items and have 4 children, meaning 16 items is needed.
/// Then checks that every item is contained in the collection.
#[concordium_test]
fn test_btree_insert_asc_height_3() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..16 {
claim!(tree.insert(n));
}
for n in 0..16 {
claim!(tree.contains(&n));
}
claim_eq!(tree.len(), 16);
claim!(!tree.contains(&17));
}
/// Insert items in a random order.
/// Then checks that every item is contained in the collection.
#[concordium_test]
fn test_btree_insert_random_order() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
tree.insert(0);
tree.insert(3);
tree.insert(2);
tree.insert(1);
tree.insert(5);
tree.insert(7);
tree.insert(6);
tree.insert(4);
for n in 0..=7 {
claim!(tree.contains(&n));
}
claim_eq!(tree.len(), 8)
}
/// Build a set and query `higher` on each key plus some keys outside of the
/// set.
#[concordium_test]
fn test_btree_higher() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
tree.insert(1);
tree.insert(2);
tree.insert(3);
tree.insert(4);
tree.insert(5);
tree.insert(7);
claim_eq!(tree.higher(&0).as_deref(), Some(&1));
claim_eq!(tree.higher(&1).as_deref(), Some(&2));
claim_eq!(tree.higher(&2).as_deref(), Some(&3));
claim_eq!(tree.higher(&3).as_deref(), Some(&4));
claim_eq!(tree.higher(&4).as_deref(), Some(&5));
claim_eq!(tree.higher(&5).as_deref(), Some(&7));
claim_eq!(tree.higher(&6).as_deref(), Some(&7));
claim_eq!(tree.higher(&7).as_deref(), None);
claim_eq!(tree.higher(&8).as_deref(), None);
}
/// Build a set and query `lower` on each key plus some keys outside of the
/// set.
#[concordium_test]
fn test_btree_lower() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
tree.insert(1);
tree.insert(2);
tree.insert(3);
tree.insert(4);
tree.insert(5);
tree.insert(7);
claim_eq!(tree.lower(&0).as_deref(), None);
claim_eq!(tree.lower(&1).as_deref(), None);
claim_eq!(tree.lower(&2).as_deref(), Some(&1));
claim_eq!(tree.lower(&3).as_deref(), Some(&2));
claim_eq!(tree.lower(&4).as_deref(), Some(&3));
claim_eq!(tree.lower(&5).as_deref(), Some(&4));
claim_eq!(tree.lower(&6).as_deref(), Some(&5));
claim_eq!(tree.lower(&7).as_deref(), Some(&5));
claim_eq!(tree.lower(&8).as_deref(), Some(&7));
}
/// Build a set and query `eq_or_higher` on each key plus some keys outside
/// of the set.
#[concordium_test]
fn test_btree_eq_or_higher() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
tree.insert(1);
tree.insert(2);
tree.insert(3);
tree.insert(4);
tree.insert(5);
tree.insert(7);
claim_eq!(tree.eq_or_higher(&0).as_deref(), Some(&1));
claim_eq!(tree.eq_or_higher(&1).as_deref(), Some(&1));
claim_eq!(tree.eq_or_higher(&2).as_deref(), Some(&2));
claim_eq!(tree.eq_or_higher(&3).as_deref(), Some(&3));
claim_eq!(tree.eq_or_higher(&4).as_deref(), Some(&4));
claim_eq!(tree.eq_or_higher(&5).as_deref(), Some(&5));
claim_eq!(tree.eq_or_higher(&6).as_deref(), Some(&7));
claim_eq!(tree.eq_or_higher(&7).as_deref(), Some(&7));
claim_eq!(tree.eq_or_higher(&8).as_deref(), None);
}
/// Build a set and query `eq_or_lower` on each key plus some keys outside
/// of the set.
#[concordium_test]
fn test_btree_eq_or_lower() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
tree.insert(1);
tree.insert(2);
tree.insert(3);
tree.insert(4);
tree.insert(5);
tree.insert(7);
claim_eq!(tree.eq_or_lower(&0).as_deref(), None);
claim_eq!(tree.eq_or_lower(&1).as_deref(), Some(&1));
claim_eq!(tree.eq_or_lower(&2).as_deref(), Some(&2));
claim_eq!(tree.eq_or_lower(&3).as_deref(), Some(&3));
claim_eq!(tree.eq_or_lower(&4).as_deref(), Some(&4));
claim_eq!(tree.eq_or_lower(&5).as_deref(), Some(&5));
claim_eq!(tree.eq_or_lower(&6).as_deref(), Some(&5));
claim_eq!(tree.eq_or_lower(&7).as_deref(), Some(&7));
claim_eq!(tree.eq_or_lower(&8).as_deref(), Some(&7));
}
/// Insert a large number of items.
/// Check the set contains each item.
/// Insert the same items again, checking the set is the same size
/// afterwards.
#[concordium_test]
fn test_btree_insert_a_lot_then_reinsert() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..500 {
claim!(tree.insert(n));
}
for n in (500..1000).into_iter().rev() {
claim!(tree.insert(n));
}
for n in 0..1000 {
claim!(tree.contains(&n))
}
claim_eq!(tree.len(), 1000);
for n in 0..1000 {
claim!(!tree.insert(n))
}
claim_eq!(tree.len(), 1000)
}
/// Remove from a btree with only the root node.
#[concordium_test]
fn test_btree_remove_from_one_node_tree() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..3 {
tree.insert(n);
}
claim!(tree.contains(&1));
claim!(tree.remove(&1));
claim!(tree.contains(&0));
claim!(!tree.contains(&1));
claim!(tree.contains(&2));
}
/// Removing from a the lower child node which is at minimum keys, causing a
/// merge.
///
/// - Builds a tree of the form: [[0], 1, [2]]
/// - Remove 0
/// - Expecting a tree of the form: [1, 2]
#[concordium_test]
fn test_btree_remove_only_key_lower_leaf_in_three_node() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..4 {
tree.insert(n);
}
tree.remove(&3);
claim!(tree.remove(&0));
claim!(!tree.contains(&0));
claim!(tree.contains(&1));
claim!(tree.contains(&2));
}
/// Removing from a the higher child node which is at minimum keys, causing
/// a merge.
///
/// - Builds a tree of the form: [[0], 1, [2]]
/// - Remove 2
/// - Expecting a tree of the form: [0, 1]
#[concordium_test]
fn test_btree_remove_only_key_higher_leaf_in_three_node() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in (0..4).into_iter().rev() {
tree.insert(n);
}
tree.remove(&3);
claim!(tree.contains(&2));
claim!(tree.remove(&2));
claim!(tree.contains(&0));
claim!(tree.contains(&1));
claim!(!tree.contains(&2));
}
/// Removing from a the higher child node which is at minimum keys, causing
/// it to move a key from its higher sibling.
///
/// - Builds a tree of the form: [[0, 1], 2, [3]]
/// - Remove 3
/// - Expecting a tree of the form: [[0], 1, [2]]
#[concordium_test]
fn test_btree_remove_from_higher_leaf_in_three_node_taking_from_sibling() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in (0..4).into_iter().rev() {
tree.insert(n);
}
claim!(tree.contains(&3));
claim!(tree.remove(&3));
claim!(!tree.contains(&3));
}
/// Removing from a the higher child node which is at minimum keys, causing
/// it to move a key from its lower sibling.
///
/// - Builds a tree of the form: [[0], 1, [2, 3]]
/// - Remove 0
/// - Expecting a tree of the form: [[1], 2, [3]]
#[concordium_test]
fn test_btree_remove_from_lower_leaf_in_three_node_taking_from_sibling() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..4 {
tree.insert(n);
}
claim!(tree.remove(&0));
claim!(!tree.contains(&0));
claim!(tree.contains(&1));
claim!(tree.contains(&2));
claim!(tree.contains(&3));
}
/// Removing from a the root node which is at minimum keys, likewise are the
/// children, causing a merge.
///
/// - Builds a tree of the form: [[0], 1, [2]]
/// - Remove 1
/// - Expecting a tree of the form: [0, 2]
#[concordium_test]
fn test_btree_remove_from_root_in_three_node_causing_merge() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..4 {
tree.insert(n);
}
tree.remove(&3);
claim!(tree.remove(&1));
claim!(tree.contains(&0));
claim!(!tree.contains(&1));
claim!(tree.contains(&2));
}
/// Removing from a the root node which is at minimum keys, taking a child
/// from its higher child.
///
/// - Builds a tree of the form: [[0], 1, [2, 3]]
/// - Remove 1
/// - Expecting a tree of the form: [[0], 2, [3]]
#[concordium_test]
fn test_btree_remove_from_root_in_three_node_taking_key_from_higher_child() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in 0..4 {
tree.insert(n);
}
claim!(tree.contains(&1));
claim!(tree.remove(&1));
claim!(!tree.contains(&1));
}
/// Removing from a the root node which is at minimum keys, taking a child
/// from its lower child.
///
/// - Builds a tree of the form: [[0, 1], 2, [3]]
/// - Remove 2
/// - Expecting a tree of the form: [[0], 1, [3]]
#[concordium_test]
fn test_btree_remove_from_root_in_three_node_taking_key_from_lower_child() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in (0..4).into_iter().rev() {
tree.insert(n);
}
claim!(tree.contains(&2));
claim!(tree.remove(&2));
claim!(!tree.contains(&2));
}
/// Test iteration of the set.
#[concordium_test]
fn test_btree_iter() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
let keys: Vec<u32> = (0..15).into_iter().collect();
for &k in &keys {
tree.insert(k);
}
let iter_keys: Vec<u32> = tree.iter().map(|k| k.clone()).collect();
claim_eq!(keys, iter_keys);
}
/// Testcase for duplicate keys in the set. Due to an edge case where the
/// key moved up as part of splitting a child node, is equal to the
/// inserted key.
///
/// - Builds a tree of the form: [[0, 1, 2], 3, [4]]
/// - Insert 1 (again) causing the [0, 1, 2] to split, moving 1 up to the
/// root.
/// - Expecting a tree of the form: [[0], 1, [2], 3, [4]]
#[concordium_test]
fn test_btree_insert_present_key() {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for n in [0, 3, 4, 1, 2].into_iter() {
tree.insert(n);
}
claim!(!tree.insert(1));
}
// The module is using `concordium_quickcheck` which is located in a deprecated
// module.
#[allow(deprecated)]
mod quickcheck {
use super::super::*;
use crate::{
self as concordium_std, concordium_quickcheck, concordium_test, fail, StateApi,
StateBuilder, StateError,
};
use ::quickcheck::{Arbitrary, Gen, TestResult};
/// Quickcheck inserting random items, check invariants on the tree and
/// query every item ensuring the tree contains it.
#[concordium_quickcheck]
fn quickcheck_btree_inserts(items: Vec<u32>) -> TestResult {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for k in items.clone() {
tree.insert(k);
}
if let Err(violation) = tree.check_invariants() {
return TestResult::error(format!("Invariant violated: {:?}", violation));
}
for k in items.iter() {
if !tree.contains(k) {
return TestResult::error(format!("Missing key: {}", k));
}
}
TestResult::passed()
}
/// Quickcheck inserting random items and then clear the entire tree
/// again. Use state api to ensure the btree nodes are no longer
/// stored in the state.
#[concordium_quickcheck]
fn quickcheck_btree_clear(items: Vec<u32>) -> TestResult {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for k in items.clone() {
tree.insert(k);
}
tree.clear();
for k in items.iter() {
if tree.contains(k) {
return TestResult::error(format!("Found {k} in a cleared btree"));
}
}
let state_api = StateApi::open();
match state_api.iterator(&tree.prefix) {
Ok(node_iter) => {
let nodes_in_state = node_iter.count();
TestResult::error(format!(
"Found {} nodes still stored in the state",
nodes_in_state
))
}
Err(StateError::SubtreeWithPrefixNotFound) => TestResult::passed(),
Err(err) => {
TestResult::error(format!("Failed to get iterator for btree nodes: {err:?}"))
}
}
}
/// Quickcheck inserting random items, then we call query the tree for
/// higher and lower of every item validating the outcome.
#[concordium_quickcheck(num_tests = 100)]
fn quickcheck_btree_iter(mut items: Vec<u32>) -> TestResult {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for k in items.clone() {
tree.insert(k);
}
if let Err(violation) = tree.check_invariants() {
return TestResult::error(format!("Invariant violated: {:?}", violation));
}
items.sort();
items.dedup();
for (value, expected) in tree.iter().zip(items.into_iter()) {
if *value != expected {
return TestResult::error(format!("Got {} but expected {expected}", *value));
}
}
TestResult::passed()
}
/// Quickcheck inserting random items, then we call query the tree for
/// higher and lower of every item validating the outcome.
#[concordium_quickcheck(num_tests = 100)]
fn quickcheck_btree_higher_lower(mut items: Vec<u32>) -> TestResult {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
for k in items.clone() {
tree.insert(k);
}
if let Err(violation) = tree.check_invariants() {
return TestResult::error(format!("Invariant violated: {:?}", violation));
}
items.sort();
items.dedup();
for window in items.windows(2) {
let l = &window[0];
let r = &window[1];
let l_higher = tree.higher(l);
if l_higher.as_deref() != Some(r) {
return TestResult::error(format!(
"higher({l}) gave {:?} instead of the expected Some({r})",
l_higher.as_deref()
));
}
let r_lower = tree.lower(r);
if r_lower.as_deref() != Some(l) {
return TestResult::error(format!(
"lower({r}) gave {:?} instead of the expected Some({l})",
r_lower.as_deref()
));
}
let space_between = r - l > 1;
if space_between {
let l_eq_or_higher = tree.eq_or_higher(&(l + 1));
if l_eq_or_higher.as_deref() != Some(r) {
return TestResult::error(format!(
"eq_or_higher({}) gave {:?} instead of the expected Some({r})",
l + 1,
l_higher.as_deref()
));
}
}
if space_between {
let r_eq_or_lower = tree.eq_or_lower(&(r - 1));
if r_eq_or_lower.as_deref() != Some(l) {
return TestResult::error(format!(
"eq_or_lower({}) gave {:?} instead of the expected Some({l})",
r - 1,
l_higher.as_deref()
));
}
}
}
if let Some(first) = items.first() {
let lower = tree.lower(first);
if lower.is_some() {
return TestResult::error(format!(
"lower({first}) gave {:?} instead of the expected None",
lower.as_deref()
));
}
}
if let Some(last) = items.last() {
let higher = tree.higher(last);
if higher.is_some() {
return TestResult::error(format!(
"higher({last}) gave {:?} instead of the expected None",
higher.as_deref()
));
}
}
TestResult::passed()
}
/// Quickcheck random mutations see `Mutations` and `run_mutations` for
/// the details.
#[concordium_quickcheck(num_tests = 500)]
fn quickcheck_btree_inserts_removes(mutations: Mutations<u32>) -> TestResult {
let mut state_builder = StateBuilder::open(StateApi::open());
let mut tree = state_builder.new_btree_set_degree::<2, _>();
if let Err(err) = run_mutations(&mut tree, &mutations.mutations) {
TestResult::error(format!("Error: {}, tree: {}", err, tree.debug()))
} else {
TestResult::passed()
}
}
/// Newtype wrapper for Vec to implement Arbitrary.
#[derive(Debug, Clone)]
struct Mutations<K> {
expected_keys: crate::collections::BTreeSet<K>,
mutations: Vec<(K, Operation)>,
}
/// The different mutating operations to generate for the btree.
#[derive(Debug, Clone, Copy)]
enum Operation {
/// Insert a new key in the set.
InsertKeyNotPresent,
/// Insert a key already in the set.
InsertKeyPresent,
/// Remove a key in the set.
RemoveKeyPresent,
/// Remove a key not already in the set.
RemoveKeyNotPresent,
}
/// Run a list of mutations on a btree, checking the return value and
/// tree invariants using `StateBTreeSet::check_invariants`
/// between each mutation, returning an error string if violated.
fn run_mutations<const M: usize>(
tree: &mut StateBTreeSet<u32, M>,
mutations: &[(u32, Operation)],
) -> Result<(), String> {
for (k, op) in mutations.into_iter() {
if let Err(violation) = tree.check_invariants() {
return Err(format!("Invariant violated: {:?}", violation));
}
match op {
Operation::InsertKeyPresent => {
if tree.insert(*k) {
return Err(format!("InsertKeyPresent was not present: {}", k));
}
}
Operation::InsertKeyNotPresent => {
if !tree.insert(*k) {
return Err(format!("InsertKeyNotPresent was present: {}", k));
}
}
Operation::RemoveKeyNotPresent => {
if tree.remove(k) {
return Err(format!("RemoveKeyNotPresent was present: {}", k));
}
}
Operation::RemoveKeyPresent => {
if !tree.remove(k) {
return Err(format!("RemoveKeyPresent was not present: {}", k));
}
}
}
}
Ok(())
}
impl Arbitrary for Operation {
fn arbitrary(g: &mut Gen) -> Self {
g.choose(&[
Self::InsertKeyNotPresent,
Self::InsertKeyPresent,
Self::RemoveKeyPresent,
Self::RemoveKeyNotPresent,
])
.unwrap()
.clone()
}
}
impl<K> Arbitrary for Mutations<K>
where
K: Arbitrary + Ord,
{
fn arbitrary(g: &mut Gen) -> Self {
// Tracking the keys expected in the set at the point of each mutation.
// This is used to ensure operations such as inserting and removing a key which
// is present are actually valid.
let mut inserted_keys: Vec<K> = Vec::new();
// The generated mutations to return.
let mut mutations = Vec::new();
while mutations.len() < g.size() {
let op: Operation = Operation::arbitrary(g);
match op {
Operation::InsertKeyPresent if inserted_keys.len() > 0 => {
let indexes: Vec<usize> =
(0..inserted_keys.len()).into_iter().collect();
let k_index = g.choose(&indexes).unwrap();
let k = &inserted_keys[*k_index];
mutations.push((k.clone(), op));
}
Operation::InsertKeyNotPresent => {
let k = K::arbitrary(g);
if let Err(index) = inserted_keys.binary_search(&k) {
inserted_keys.insert(index, k.clone());
mutations.push((k, op));
}
}
Operation::RemoveKeyPresent if inserted_keys.len() > 0 => {
let indexes: Vec<usize> =
(0..inserted_keys.len()).into_iter().collect();
let k_index = g.choose(&indexes).unwrap();
let k = inserted_keys.remove(*k_index);
mutations.push((k, op));
}
Operation::RemoveKeyNotPresent => {
let k = K::arbitrary(g);
if inserted_keys.binary_search(&k).is_err() {
mutations.push((k, op));
}
}
_ => {}
}
}
Self {
expected_keys: crate::collections::BTreeSet::from_iter(
inserted_keys.into_iter(),
),
mutations,
}
}
/// We attempt to produce several shrinked versions:
///
/// - Simply remove the last mutation from the list of mutations.
/// - Remove mutations, which are not adding or removing keys
/// (Remove non-present keys and inserting present keys), note
/// these might still mutate the internal structure.
/// - Iterate the mutations and when a key is removed, we traverse
/// back in the mutations and remove other mutations of the same
/// key back to when it was inserted.
fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
let pop = {
let mut clone = self.clone();
clone.mutations.pop();
clone
};
let mut v = vec![pop];
for (i, (k, op)) in self.mutations.iter().enumerate() {
match op {
Operation::InsertKeyPresent | Operation::RemoveKeyNotPresent => {
let mut clone = self.clone();
clone.mutations.remove(i);
v.push(clone);
}
Operation::RemoveKeyPresent => {
let mut clone = self.clone();
let mut prev = self.mutations[0..i].iter().enumerate().rev();
clone.mutations.remove(i);
clone.expected_keys.remove(k);
loop {
if let Some((j, (k2, op))) = prev.next() {
match op {
Operation::InsertKeyPresent if k == k2 => {
clone.mutations.remove(j);
}
Operation::InsertKeyNotPresent if k == k2 => {
clone.mutations.remove(j);
break;
}
_ => {}
}
} else {
fail!("No insertion found before")
}
}
v.push(clone);
}
_ => {}
}
}
Box::new(v.into_iter())
}
}
}
}