1use std::{fmt::Debug, ops::Add};
  2use sum_tree::{ContextLessSummary, Dimension, Edit, Item, KeyedItem, SumTree};
  3
  4pub trait Operation: Clone + Debug {
  5    fn lamport_timestamp(&self) -> clock::Lamport;
  6}
  7
  8#[derive(Clone, Debug)]
  9struct OperationItem<T>(T);
 10
 11#[derive(Clone, Debug)]
 12pub struct OperationQueue<T: Operation>(SumTree<OperationItem<T>>);
 13
 14#[derive(Clone, Copy, Debug, Default, Eq, Ord, PartialEq, PartialOrd)]
 15pub struct OperationKey(clock::Lamport);
 16
 17#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
 18pub struct OperationSummary {
 19    pub key: OperationKey,
 20    pub len: usize,
 21}
 22
 23impl OperationKey {
 24    pub fn new(timestamp: clock::Lamport) -> Self {
 25        Self(timestamp)
 26    }
 27}
 28
 29impl<T: Operation> Default for OperationQueue<T> {
 30    fn default() -> Self {
 31        OperationQueue::new()
 32    }
 33}
 34
 35impl<T: Operation> OperationQueue<T> {
 36    pub fn new() -> Self {
 37        OperationQueue(SumTree::default())
 38    }
 39
 40    pub fn len(&self) -> usize {
 41        self.0.summary().len
 42    }
 43
 44    pub fn is_empty(&self) -> bool {
 45        self.len() == 0
 46    }
 47
 48    pub fn insert(&mut self, mut ops: Vec<T>) {
 49        ops.sort_by_key(|op| op.lamport_timestamp());
 50        ops.dedup_by_key(|op| op.lamport_timestamp());
 51        self.0.edit(
 52            ops.into_iter()
 53                .map(|op| Edit::Insert(OperationItem(op)))
 54                .collect(),
 55            (),
 56        );
 57    }
 58
 59    pub fn drain(&mut self) -> Self {
 60        let clone = self.clone();
 61        self.0 = SumTree::default();
 62        clone
 63    }
 64
 65    pub fn iter(&self) -> impl Iterator<Item = &T> {
 66        self.0.iter().map(|i| &i.0)
 67    }
 68}
 69
 70impl ContextLessSummary for OperationSummary {
 71    fn zero() -> Self {
 72        Default::default()
 73    }
 74
 75    fn add_summary(&mut self, other: &Self) {
 76        assert!(self.key < other.key);
 77        self.key = other.key;
 78        self.len += other.len;
 79    }
 80}
 81
 82impl Add<&Self> for OperationSummary {
 83    type Output = Self;
 84
 85    fn add(self, other: &Self) -> Self {
 86        assert!(self.key < other.key);
 87        OperationSummary {
 88            key: other.key,
 89            len: self.len + other.len,
 90        }
 91    }
 92}
 93
 94impl Dimension<'_, OperationSummary> for OperationKey {
 95    fn zero(_cx: ()) -> Self {
 96        Default::default()
 97    }
 98
 99    fn add_summary(&mut self, summary: &OperationSummary, _: ()) {
100        assert!(*self <= summary.key);
101        *self = summary.key;
102    }
103}
104
105impl<T: Operation> Item for OperationItem<T> {
106    type Summary = OperationSummary;
107
108    fn summary(&self, _cx: ()) -> Self::Summary {
109        OperationSummary {
110            key: OperationKey::new(self.0.lamport_timestamp()),
111            len: 1,
112        }
113    }
114}
115
116impl<T: Operation> KeyedItem for OperationItem<T> {
117    type Key = OperationKey;
118
119    fn key(&self) -> Self::Key {
120        OperationKey::new(self.0.lamport_timestamp())
121    }
122}
123
124#[cfg(test)]
125mod tests {
126    use super::*;
127
128    #[test]
129    fn test_len() {
130        let mut clock = clock::Lamport::new(0);
131
132        let mut queue = OperationQueue::new();
133        assert_eq!(queue.len(), 0);
134
135        queue.insert(vec![
136            TestOperation(clock.tick()),
137            TestOperation(clock.tick()),
138        ]);
139        assert_eq!(queue.len(), 2);
140
141        queue.insert(vec![TestOperation(clock.tick())]);
142        assert_eq!(queue.len(), 3);
143
144        drop(queue.drain());
145        assert_eq!(queue.len(), 0);
146
147        queue.insert(vec![TestOperation(clock.tick())]);
148        assert_eq!(queue.len(), 1);
149    }
150
151    #[derive(Clone, Debug, Eq, PartialEq)]
152    struct TestOperation(clock::Lamport);
153
154    impl Operation for TestOperation {
155        fn lamport_timestamp(&self) -> clock::Lamport {
156            self.0
157        }
158    }
159}