pavan51 commented on code in PR #23827:
URL: https://github.com/apache/datafusion/pull/23827#discussion_r3643933874
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datafusion/functions-aggregate/src/min_max.rs:
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@@ -790,72 +790,55 @@ impl<T: Clone + PartialOrd> MovingMin<T> {
#[inline]
pub fn with_capacity(capacity: usize) -> Self {
Self {
- push_stack: Vec::with_capacity(capacity),
- pop_stack: Vec::with_capacity(capacity),
+ fifo: std::collections::VecDeque::with_capacity(capacity),
+ deque: std::collections::VecDeque::with_capacity(capacity),
}
}
/// Returns the minimum of the sliding window or `None` if the window is
/// empty.
#[inline]
pub fn min(&self) -> Option<&T> {
- match (self.push_stack.last(), self.pop_stack.last()) {
- (None, None) => None,
- (Some((_, min)), None) => Some(min),
- (None, Some((_, min))) => Some(min),
- (Some((_, a)), Some((_, b))) => Some(if a < b { a } else { b }),
- }
+ self.deque.front()
}
/// Pushes a new element into the sliding window.
#[inline]
pub fn push(&mut self, val: T) {
- self.push_stack.push(match self.push_stack.last() {
- Some((_, min)) => {
- if val > *min {
- (val, min.clone())
- } else {
- (val.clone(), val)
- }
- }
- None => (val.clone(), val),
- });
+ self.fifo.push_back(val.clone());
+ while self.deque.back().map_or(false, |back_val| *back_val > val) {
+ self.deque.pop_back();
+ }
+ self.deque.push_back(val);
}
/// Removes and returns the last value of the sliding window.
#[inline]
pub fn pop(&mut self) -> Option<T> {
Review Comment:
I have refactored the implementation to use this sequence number approach.
The fifo queue has been removed entirely, and pop() now returns (), which
significantly simplified the code.
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