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use std::sync::atomic::Ordering;
use super::baildon::Baildon;
use super::baildon::Direction;
use super::node::Node;
use futures::stream;
use futures::Stream;
use futures::StreamExt;
use serde::de::DeserializeOwned;
use serde::Serialize;
impl<K, V> Baildon<K, V>
where
K: Clone + Ord + Serialize + DeserializeOwned + std::fmt::Debug + Send + Sync,
V: Clone + Serialize + DeserializeOwned + std::fmt::Debug + Send + Sync,
{
/// Return a stream of entries
pub async fn entries(&self, direction: Direction) -> impl Stream<Item = (K, V)> + '_ {
let mut streamer = self.stream_all_leaf_nodes(direction).await;
let index = 0;
let leaf_opt = streamer.next().await;
// Each node contains a number of values, we must read all the values from the current node
// before advancing. (i.e.: a loop within a loop)
Box::pin(stream::unfold(
(streamer, leaf_opt, index),
move |mut triplet| async move {
loop {
match &triplet.1 {
Some(leaf) => {
let pair_opt = if direction == Direction::Ascending {
leaf.pairs().nth(triplet.2)
} else {
leaf.pairs().rev().nth(triplet.2)
};
match pair_opt {
Some(pair) => {
triplet.2 += 1;
break Some(((pair.0.clone(), pair.1.clone()), triplet));
}
None => {
triplet.1 = triplet.0.next().await;
triplet.2 = 0;
continue;
}
}
}
None => break None,
};
}
},
))
}
/// Return a stream of keys
pub async fn keys(&self, direction: Direction) -> impl Stream<Item = K> + '_ {
let mut streamer = self.stream_all_leaf_nodes(direction).await;
let index = 0;
let leaf_opt = streamer.next().await;
// Each node contains a number of keys, we must read all the keys from the current node
// before advancing. (i.e.: a loop within a loop)
Box::pin(stream::unfold(
(streamer, leaf_opt, index),
move |mut triplet| async move {
loop {
match &triplet.1 {
Some(leaf) => {
let key_opt = if direction == Direction::Ascending {
leaf.keys().nth(triplet.2)
} else {
leaf.keys().rev().nth(triplet.2)
};
match key_opt {
Some(key) => {
triplet.2 += 1;
break Some(((*key).clone(), triplet));
}
None => {
triplet.1 = triplet.0.next().await;
triplet.2 = 0;
continue;
}
}
}
None => break None,
}
}
},
))
}
/// Return a stream of values
pub async fn values(&self, direction: Direction) -> impl Stream<Item = V> + '_ {
let mut streamer = self.stream_all_leaf_nodes(direction).await;
let index = 0;
let leaf_opt = streamer.next().await;
// Each node contains a number of values, we must read all the values from the current node
// before advancing. (i.e.: a loop within a loop)
Box::pin(stream::unfold(
(streamer, leaf_opt, index),
move |mut triplet| async move {
loop {
match &triplet.1 {
Some(leaf) => {
let value_opt = if direction == Direction::Ascending {
leaf.values().nth(triplet.2)
} else {
leaf.values().rev().nth(triplet.2)
};
match value_opt {
Some(value) => {
triplet.2 += 1;
break Some(((*value).clone(), triplet));
}
None => {
triplet.1 = triplet.0.next().await;
triplet.2 = 0;
continue;
}
}
}
None => break None,
};
}
},
))
}
pub(crate) async fn stream_all_nodes(
&self,
direction: Direction,
) -> impl Stream<Item = Node<K, V>> + '_ {
let seed = if direction == Direction::Ascending {
1
} else {
self.index.load(Ordering::SeqCst)
};
self.inner_stream_nodes(seed, direction).await
}
async fn inner_stream_nodes(
&self,
seed_idx: usize,
direction: Direction,
) -> impl Stream<Item = Node<K, V>> + '_ {
let node_count = self.index.load(Ordering::SeqCst);
Box::pin(stream::unfold(seed_idx, move |mut idx| async move {
let mut nodes_lock = self.nodes.lock().await;
match direction {
Direction::Descending => {
// Needed to protect header record
while idx > 0 {
match self.find_node_with_lock(&mut nodes_lock, idx).await {
Ok(node) => {
return Some((node, idx - 1));
}
Err(_e) => {
idx -= 1;
}
}
}
None
}
Direction::Ascending => {
// Needed to protect header record
while idx > 0 && idx < node_count {
match self.find_node_with_lock(&mut nodes_lock, idx).await {
Ok(node) => {
return Some((node, idx + 1));
}
Err(_e) => {
idx += 1;
}
}
}
None
}
}
}))
}
pub(crate) async fn stream_all_leaf_nodes(
&self,
direction: Direction,
) -> impl Stream<Item = Node<K, V>> + '_ {
let seed = if direction == Direction::Ascending {
self.first_leaf().await
} else {
self.last_leaf().await
};
self.inner_stream_leaf_nodes(seed, direction)
}
fn inner_stream_leaf_nodes(
&self,
seed: Node<K, V>,
direction: Direction,
) -> impl Stream<Item = Node<K, V>> + '_ {
Box::pin(stream::unfold(Some(seed), move |node_opt| async move {
match node_opt {
Some(node) => match self.neighbour(node.index(), direction).await {
Some(ns) => Some((node, Some(ns))),
None => Some((node, None)),
},
None => None,
}
}))
}
}
#[cfg(test)]
mod tests {
use super::*;
use futures::StreamExt;
#[test_log::test(tokio::test)]
async fn it_streams_leaf_nodes() {
// Create test tree
let tree = Baildon::<usize, usize>::try_new("streams_tree.db", 4)
.await
.expect("creates tree file");
let input = vec![
7, 8, 14, 20, 21, 27, 34, 42, 43, 47, 48, 52, 64, 72, 90, 91, 93, 94, 97,
];
for i in &input {
tree.insert(*i, *i).await.expect("insert worked");
}
// Test Ascending stream
let mut streamer = tree.stream_all_leaf_nodes(Direction::Ascending).await;
let mut slice_index = 0;
while let Some(node) = streamer.next().await {
let slice_len = node.len();
let a = &node.keys().cloned().collect::<Vec<usize>>()[..];
let b = &input[slice_index..slice_index + slice_len];
assert_eq!(a, b);
slice_index += slice_len;
}
// Test Descending stream
let mut streamer = tree.stream_all_leaf_nodes(Direction::Descending).await;
let mut slice_index = input.len();
while let Some(node) = streamer.next().await {
let slice_len = node.len();
let a = &node.keys().cloned().collect::<Vec<usize>>()[..];
let b = &input[slice_index - slice_len..slice_index];
assert_eq!(a, b);
slice_index -= slice_len;
}
// Delete test tree
std::fs::remove_file("streams_tree.db").expect("cleanup");
}
}