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use ahash::AHashMap;
use smartstring::alias::String;
#[derive(Default)]
pub struct Counter {
counts: AHashMap<String, u64>,
top: AHashMap<String, u64>,
threshold: u64,
num: usize,
}
impl Counter {
pub fn new(num: Option<usize>) -> Self {
Self {
num: num.unwrap_or(0),
threshold: num.map(|_| 0).unwrap_or(u64::MAX),
..Default::default()
}
}
pub fn add(&mut self, key: &str, added: u64) {
let count = match self.counts.get_mut(key) {
Some(count) => {
*count += added;
*count
}
None => {
self.counts.insert(key.into(), added);
added
}
};
if count < self.threshold {
return;
}
if let Some(t) = self.top.get_mut(key) {
*t = count;
return;
}
self.top.insert(key.into(), count);
if self.top.len() < self.num * 2 {
return;
}
let mut top_values = self.top.values().collect::<Vec<_>>();
top_values.sort_unstable();
let threshold = *top_values[self.num as usize - 1];
self.threshold = threshold;
self.top.retain(|_, v| *v > threshold);
}
pub fn top(&self) -> Vec<KeyCount> {
let mut top = Vec::with_capacity(self.num);
for (key, &count) in &self.top {
top.push(KeyCount {
count,
key: key.clone(),
});
}
top.sort_unstable();
top.reverse();
if self.num > 0 {
top.truncate(self.num);
}
top
}
pub fn merge(mut self, r: Counter) -> Self {
for (key, count) in r.counts.iter() {
self.add(key, *count);
}
self
}
}
#[derive(PartialEq, PartialOrd, Eq, Ord)]
pub struct KeyCount {
pub count: u64,
pub key: String,
}