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use async_trait::async_trait;
use futures::{
channel::mpsc::{UnboundedReceiver, UnboundedSender},
FutureExt, SinkExt, StreamExt,
};
use std::hint;
pub enum Instruction {
Ok,
Clear,
}
pub struct ResponseWithInstruction<T> {
pub resp: T,
pub instruction: Instruction,
}
impl<T> From<T> for ResponseWithInstruction<T> {
fn from(val: T) -> Self {
Self {
resp: val,
instruction: Instruction::Ok,
}
}
}
#[async_trait]
pub trait StatelessPipeline: Send + Sync {
type Request;
type Response;
async fn process(&self, req: Self::Request) -> ResponseWithInstruction<Self::Response>;
}
pub struct PipelinePhase<T: StatelessPipeline> {
rx: UnboundedReceiver<T::Request>,
tx: UnboundedSender<T::Response>,
processor: Box<T>,
}
impl<T: StatelessPipeline> PipelinePhase<T> {
pub fn new(
rx: UnboundedReceiver<T::Request>,
tx: UnboundedSender<T::Response>,
processor: Box<T>,
) -> Self {
Self { rx, tx, processor }
}
pub fn exhaust_requests_non_blocking(&mut self) {
while self.rx.next().now_or_never().is_some() {
hint::spin_loop()
}
}
pub async fn start(mut self) {
while let Some(req) = self.rx.next().await {
let ResponseWithInstruction { resp, instruction } = self.processor.process(req).await;
match instruction {
Instruction::Ok => {}
Instruction::Clear => self.exhaust_requests_non_blocking(),
}
if self.tx.send(resp).await.is_err() {
break;
}
}
}
}