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use std::sync::Mutex;
use super::LoadBalancingStrategy;
pub struct RoundRobinSync<N> {
cluster: Vec<N>,
prev_idx: Mutex<usize>,
}
impl<N> RoundRobinSync<N> {
pub fn new() -> Self {
RoundRobinSync {
prev_idx: Mutex::new(0),
cluster: vec![],
}
}
}
impl<N> From<Vec<N>> for RoundRobinSync<N> {
fn from(cluster: Vec<N>) -> RoundRobinSync<N> {
RoundRobinSync {
prev_idx: Mutex::new(0),
cluster: cluster,
}
}
}
impl<N> LoadBalancingStrategy<N> for RoundRobinSync<N> {
fn init(&mut self, cluster: Vec<N>) {
self.cluster = cluster;
}
fn next(&self) -> Option<&N> {
let mut prev_idx = self.prev_idx.lock();
if let Ok(ref mut mtx) = prev_idx {
let next_idx = (**mtx + 1) % self.cluster.len();
**mtx = next_idx;
self.cluster.get(next_idx)
} else {
return None;
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn round_robin() {
let nodes = vec!["a", "b", "c"];
let nodes_c = nodes.clone();
let load_balancer = RoundRobinSync::from(nodes);
for i in 0..10 {
assert_eq!(&nodes_c[(i + 1) % 3], load_balancer.next().unwrap());
}
}
}