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use merfolk::{interfaces::Backend, Call, Reply}; use anyhow::Result; use thiserror::Error; use std::sync::Arc; use tokio::runtime::Runtime; use tokio::sync::{ mpsc, mpsc::{Receiver, Sender}, }; use log::trace; pub type InProcessChannel = (Call<String>, Sender<Result<Reply<String>>>); #[derive(Debug, Error)] pub enum Error { #[error("derializing failed: {0}")] Serialize(#[source] serde_json::Error), #[error("deserializing failed: {0}")] Deserialize(#[source] serde_json::Error), #[error("no receiver was registered by the init() function")] NoReceiver, #[error("no `to` channel was provided in init()")] NoCallerChannel, #[error("no `from` channel was provided in init()")] NoReceiverChannel, #[error("recv() from `rx` channel failed")] CallerRecv, #[error("send() to `to` channel failed: {0}")] CallerSend(#[from] tokio::sync::mpsc::error::SendError<InProcessChannel>), #[error("could not create runtime: {0}")] RuntimeCreation(#[from] std::io::Error), #[error("already started")] AlreadyStarted, #[error("not yet started")] NotStarted, } #[derive(derive_builder::Builder)] #[builder(pattern = "owned")] pub struct InProcess { #[allow(clippy::type_complexity)] #[builder(private, default = "None")] receiver: Option<Arc<dyn Fn(Call<String>) -> Result<Reply<String>> + Send + Sync>>, #[builder(private, default = "Runtime::new().map_err(Error::RuntimeCreation).map_err(|e| e.to_string())?")] runtime: Runtime, #[builder(private, default = "None")] handle: Option<tokio::task::JoinHandle<std::convert::Infallible>>, #[builder(setter(into, strip_option), default = "None")] to: Option<Sender<InProcessChannel>>, #[builder(setter(into, strip_option, name = "from_setter"), private, default = "None")] from: Option<Arc<tokio::sync::Mutex<Receiver<InProcessChannel>>>>, } impl InProcessBuilder { pub fn from(self, value: Receiver<InProcessChannel>) -> Self { self.from_setter(Arc::new(tokio::sync::Mutex::new(value))) } } impl InProcess { pub fn builder() -> InProcessBuilder { InProcessBuilder::default() } } impl InProcess { pub fn start(&mut self) -> Result<()> { trace!("start InProcess"); if self.handle.is_some() { return Err(Error::AlreadyStarted.into()); } let from = self.from.as_ref().ok_or(Error::NoReceiverChannel)?.clone(); let receiver = self.receiver.as_ref().ok_or(Error::NoReceiver)?.clone(); self.handle = Some(self.runtime.spawn(async move { loop { let (call, tx) = from.lock().await.recv().await.unwrap(); let reply = receiver(Call { procedure: call.procedure, payload: call.payload, }); tx.send(reply).await.unwrap(); } })); Ok(()) } pub fn stop(&mut self) -> Result<()> { trace!("stop InProcess"); match &self.handle { None => Err(Error::NotStarted.into()), Some(handle) => { handle.abort(); Ok(()) } } } } impl Backend for InProcess { type Intermediate = String; fn register<T>(&mut self, receiver: T) -> Result<()> where T: Fn(Call<Self::Intermediate>) -> Result<Reply<Self::Intermediate>> + Send + Sync + 'static, { trace!("register receiver"); self.receiver = Some(Arc::new(move |call: Call<String>| receiver(call))); self.start().ok(); Ok(()) } fn call(&mut self, call: Call<Self::Intermediate>) -> Result<Reply<Self::Intermediate>> { trace!("receive call"); self.runtime.block_on(async { #[allow(clippy::type_complexity)] let (tx, mut rx): (Sender<Result<Reply<String>>>, Receiver<Result<Reply<String>>>) = mpsc::channel(1); self .to .as_ref() .ok_or(Error::NoCallerChannel)? .send(( Call { procedure: call.procedure.clone(), payload: call.payload.clone(), }, tx, )) .await .map_err(Error::CallerSend)?; rx.recv().await.ok_or(Error::CallerRecv)? }) } fn serialize<T: serde::Serialize>(from: &T) -> Result<String> { trace!("serialize from"); serde_json::to_string(from).map_err(|e| Error::Serialize(e).into()) } fn deserialize<'b, T>(from: &'b Self::Intermediate) -> Result<T> where T: for<'de> serde::Deserialize<'de>, { trace!("deserialize from"); serde_json::from_str(&from).map_err(|e| Error::Deserialize(e).into()) } } impl Drop for InProcess { fn drop(&mut self) { self.stop().unwrap() } }