feat: implement asynchronous channel support with tokio integration

Cargo.toml

@@ -18,20 +18,24 @@ thiserror = "2.0"
 flume = { version = "0.12", optional = true }
 crossbeam-channel = { version = "0.5", optional = true }
 arc-swap = "1.7.1"
+tokio = { version = "1.48", features = ["sync", "macros", "rt-multi-thread"], optional = true }
+async-trait = { version = "0.1", optional = true }
 
 [features]
 default = ["all"]
 
 sync = []
-async = []
+async = ["dep:async-trait"]
 
 sync-std = ["sync"]
 sync-flume = ["sync", "dep:flume"]
 sync-crossbeam = ["sync", "dep:crossbeam-channel"]
+async-tokio = ["async", "dep:tokio"]
 
 all-sync = ["sync-std", "sync-flume", "sync-crossbeam"]
+all-async = ["async-tokio"]
 
-all = ["all-sync"]
+all = ["all-sync", "all-async"]
 
 [lib]
 

rust-toolchain.toml

@@ -1,3 +0,0 @@
-[toolchain]
-channel = "stable"
-profile = "default"

src/async_channel.rs

@@ -0,0 +1,196 @@
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, Mutex};
+
+use crate::asynchronous::traits::{AsyncChannelReceiver, AsyncChannelSender};
+use crate::error::Error;
+use crate::types::{ChannelState, Request, Response, ValueSource};
+
+/// The consumer side of the channel that requests values asynchronously.
+pub struct AsyncSucker<T, ST, SR>
+where
+    ST: AsyncChannelSender<Request>,
+    SR: AsyncChannelReceiver<Response<T>>,
+{
+    request_tx: ST,
+    response_rx: SR,
+    closed: AtomicBool,
+    _phantom: std::marker::PhantomData<T>,
+}
+
+impl<T, ST, SR> AsyncSucker<T, ST, SR>
+where
+    ST: AsyncChannelSender<Request>,
+    SR: AsyncChannelReceiver<Response<T>>,
+{
+    pub(crate) fn new(request_tx: ST, response_rx: SR) -> Self {
+        Self {
+            request_tx,
+            response_rx,
+            closed: AtomicBool::new(false),
+            _phantom: std::marker::PhantomData,
+        }
+    }
+}
+
+/// The producer side of the channel that provides values asynchronously.
+pub struct AsyncSourcer<T, SR, ST>
+where
+    SR: AsyncChannelReceiver<Request>,
+    ST: AsyncChannelSender<Response<T>>,
+{
+    request_rx: SR,
+    response_tx: ST,
+    state: ChannelState<T>,
+    _phantom: std::marker::PhantomData<T>,
+}
+
+impl<T, SR, ST> AsyncSourcer<T, SR, ST>
+where
+    SR: AsyncChannelReceiver<Request>,
+    ST: AsyncChannelSender<Response<T>>,
+{
+    pub(crate) fn new(request_rx: SR, response_tx: ST, state: ChannelState<T>) -> Self {
+        Self {
+            request_rx,
+            response_tx,
+            state,
+            _phantom: std::marker::PhantomData,
+        }
+    }
+}
+
+impl<T, SR, ST> AsyncSourcer<T, SR, ST>
+where
+    T: Send + 'static,
+    SR: AsyncChannelReceiver<Request>,
+    ST: AsyncChannelSender<Response<T>>,
+{
+    pub fn set_static(&self, val: T) -> Result<(), Error>
+    where
+        T: Clone,
+    {
+        self.state.swap(Arc::new(ValueSource::Static {
+            val,
+            clone: T::clone,
+        }));
+        Ok(())
+    }
+
+    pub fn set<F>(&self, closure: F) -> Result<(), Error>
+    where
+        F: Fn() -> T + Send + Sync + 'static,
+    {
+        self.state
+            .swap(Arc::new(ValueSource::Dynamic(Box::new(closure))));
+        Ok(())
+    }
+
+    pub fn set_mut<F>(&self, closure: F) -> Result<(), Error>
+    where
+        F: FnMut() -> T + Send + Sync + 'static,
+    {
+        self.state
+            .swap(Arc::new(ValueSource::DynamicMut(Mutex::new(Box::new(
+                closure,
+            )))));
+        Ok(())
+    }
+
+    pub fn close(&self) -> Result<(), Error> {
+        self.state.swap(Arc::new(ValueSource::Cleared));
+        Ok(())
+    }
+
+    pub async fn run(self) -> Result<(), Error> {
+        loop {
+            match self.request_rx.recv().await {
+                Ok(Request::GetValue) => {
+                    let response = self.handle_get_value()?;
+                    if self.response_tx.send(response).await.is_err() {
+                        break;
+                    }
+                }
+                Ok(Request::Close) => {
+                    self.close()?;
+                    break;
+                }
+                Err(_) => break,
+            }
+        }
+        Ok(())
+    }
+
+    fn handle_get_value(&self) -> Result<Response<T>, Error> {
+        let state = self.state.load();
+
+        match &**state {
+            ValueSource::Static { val, clone } => {
+                let value = self.execute_closure_safely(&mut || clone(val));
+                match value {
+                    Ok(v) => Ok(Response::Value(v)),
+                    Err(_) => Ok(Response::NoSource),
+                }
+            }
+            ValueSource::Dynamic(closure) => {
+                let value = self.execute_closure_safely(&mut || closure());
+                match value {
+                    Ok(v) => Ok(Response::Value(v)),
+                    Err(_) => Ok(Response::NoSource),
+                }
+            }
+            ValueSource::DynamicMut(closure) => {
+                let mut closure = closure.lock().unwrap();
+                let value = self.execute_closure_safely(&mut *closure);
+                match value {
+                    Ok(v) => Ok(Response::Value(v)),
+                    Err(_) => Ok(Response::NoSource),
+                }
+            }
+            ValueSource::None => Ok(Response::NoSource),
+            ValueSource::Cleared => Ok(Response::Closed),
+        }
+    }
+
+    fn execute_closure_safely(
+        &self,
+        closure: &mut dyn FnMut() -> T,
+    ) -> Result<T, Box<dyn std::any::Any + Send>> {
+        std::panic::catch_unwind(std::panic::AssertUnwindSafe(closure))
+    }
+}
+
+impl<T, ST, SR> AsyncSucker<T, ST, SR>
+where
+    ST: AsyncChannelSender<Request>,
+    SR: AsyncChannelReceiver<Response<T>>,
+{
+    pub async fn get(&self) -> Result<T, Error> {
+        if self.closed.load(Ordering::Acquire) {
+            return Err(Error::ChannelClosed);
+        }
+
+        self.request_tx
+            .send(Request::GetValue)
+            .await
+            .map_err(|_| Error::ProducerDisconnected)?;
+
+        match self.response_rx.recv().await {
+            Ok(Response::Value(value)) => Ok(value),
+            Ok(Response::NoSource) => Err(Error::NoSource),
+            Ok(Response::Closed) => Err(Error::ChannelClosed),
+            Err(_) => Err(Error::ProducerDisconnected),
+        }
+    }
+
+    pub async fn is_closed(&self) -> bool {
+        self.request_tx.send(Request::GetValue).await.is_err()
+    }
+
+    pub async fn close(&self) -> Result<(), Error> {
+        self.closed.store(true, Ordering::Release);
+        self.request_tx
+            .send(Request::Close)
+            .await
+            .map_err(|_| Error::ProducerDisconnected)
+    }
+}

src/asynchronous/mod.rs

@@ -0,0 +1,7 @@
+pub mod traits;
+
+#[cfg(feature = "async-tokio")]
+pub mod tokio;
+
+#[cfg(feature = "async-tokio")]
+pub use tokio::TokioSuck;

src/asynchronous/tokio.rs

@@ -0,0 +1,113 @@
+use std::sync::Arc;
+
+use arc_swap::ArcSwap;
+use async_trait::async_trait;
+use tokio::sync::{Mutex, mpsc};
+
+use crate::asynchronous::traits::{
+    AsyncChannelReceiver, AsyncChannelSender, AsyncChannelType, ChannelError,
+};
+use crate::types;
+
+type TokioSucker<T> =
+    crate::AsyncSucker<T, TokioSender<types::Request>, TokioReceiver<types::Response<T>>>;
+type TokioSourcer<T> =
+    crate::AsyncSourcer<T, TokioReceiver<types::Request>, TokioSender<types::Response<T>>>;
+
+pub struct TokioSender<T>(mpsc::UnboundedSender<T>);
+pub struct TokioReceiver<T>(Mutex<mpsc::UnboundedReceiver<T>>);
+
+#[async_trait]
+impl<T: Send + 'static> AsyncChannelSender<T> for TokioSender<T> {
+    async fn send(&self, msg: T) -> Result<(), ChannelError> {
+        self.0
+            .send(msg)
+            .map_err(|_| ChannelError::ProducerDisconnected)
+    }
+}
+
+#[async_trait]
+impl<T: Send + 'static> AsyncChannelReceiver<T> for TokioReceiver<T> {
+    async fn recv(&self) -> Result<T, ChannelError> {
+        let mut receiver = self.0.lock().await;
+        receiver
+            .recv()
+            .await
+            .ok_or(ChannelError::ProducerDisconnected)
+    }
+}
+
+pub struct TokioChannel;
+
+impl AsyncChannelType for TokioChannel {
+    type Sender<T: Send + 'static> = TokioSender<T>;
+    type Receiver<T: Send + 'static> = TokioReceiver<T>;
+
+    fn create_request_channel() -> (Self::Sender<types::Request>, Self::Receiver<types::Request>) {
+        let (tx, rx) = mpsc::unbounded_channel();
+        (TokioSender(tx), TokioReceiver(Mutex::new(rx)))
+    }
+
+    fn create_response_channel<T: Send + 'static>() -> (
+        Self::Sender<types::Response<T>>,
+        Self::Receiver<types::Response<T>>,
+    ) {
+        let (tx, rx) = mpsc::unbounded_channel();
+        (TokioSender(tx), TokioReceiver(Mutex::new(rx)))
+    }
+}
+
+pub struct TokioSuck<T> {
+    _phantom: std::marker::PhantomData<T>,
+}
+
+impl<T> TokioSuck<T> {
+    pub fn pair() -> (TokioSucker<T>, TokioSourcer<T>)
+    where
+        T: Clone + Send + 'static,
+    {
+        let (request_tx, request_rx) = TokioChannel::create_request_channel();
+        let (response_tx, response_rx) = TokioChannel::create_response_channel::<T>();
+        let state = ArcSwap::new(Arc::new(crate::types::ValueSource::None));
+
+        let sucker = crate::AsyncSucker::new(request_tx, response_rx);
+        let sourcer = crate::AsyncSourcer::new(request_rx, response_tx, state);
+
+        (sucker, sourcer)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::Error;
+
+    #[tokio::test]
+    async fn test_pre_computed_value() {
+        let (sucker, sourcer) = TokioSuck::<i32>::pair();
+
+        let producer = tokio::spawn(async move {
+            sourcer.set_static(42).unwrap();
+            sourcer.run().await.unwrap();
+        });
+
+        let value = sucker.get().await.unwrap();
+        assert_eq!(value, 42);
+        sucker.close().await.unwrap();
+        producer.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_no_source_error() {
+        let (sucker, sourcer) = TokioSuck::<i32>::pair();
+
+        let producer = tokio::spawn(async move {
+            sourcer.run().await.unwrap();
+        });
+
+        let result = sucker.get().await;
+        assert!(matches!(result, Err(Error::NoSource)));
+        sucker.close().await.unwrap();
+        producer.await.unwrap();
+    }
+}

src/asynchronous/traits.rs

@@ -0,0 +1,27 @@
+use async_trait::async_trait;
+
+pub use crate::error::Error as ChannelError;
+
+#[async_trait]
+pub trait AsyncChannelSender<T>: Send + Sync {
+    async fn send(&self, msg: T) -> Result<(), ChannelError>;
+}
+
+#[async_trait]
+pub trait AsyncChannelReceiver<T>: Send + Sync {
+    async fn recv(&self) -> Result<T, ChannelError>;
+}
+
+pub trait AsyncChannelType {
+    type Sender<T: Send + 'static>: AsyncChannelSender<T>;
+    type Receiver<T: Send + 'static>: AsyncChannelReceiver<T>;
+
+    fn create_request_channel() -> (
+        Self::Sender<crate::types::Request>,
+        Self::Receiver<crate::types::Request>,
+    );
+    fn create_response_channel<T: Send + 'static>() -> (
+        Self::Sender<crate::types::Response<T>>,
+        Self::Receiver<crate::types::Response<T>>,
+    );
+}

src/channel.rs

@@ -2,7 +2,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
 
 use crate::error::Error;
-use crate::sync::traits::{ChannelReceiver, ChannelSender};
+use crate::traits::{ChannelReceiver, ChannelSender};
 use crate::types::{ChannelState, Request, Response, ValueSource};
 
 /// The consumer side of the channel that requests values

src/lib.rs

@@ -1,12 +1,19 @@
 #![doc = include_str!("../README.md")]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 
+#[cfg(feature = "async")]
+pub mod async_channel;
 pub mod channel;
 pub mod error;
+pub mod traits;
 
+#[cfg(feature = "async")]
+pub mod asynchronous;
 #[cfg(feature = "sync")]
 pub mod sync;
 pub mod types;
 
+#[cfg(feature = "async")]
+pub use async_channel::{AsyncSourcer, AsyncSucker};
 pub use channel::{Sourcer, Sucker};
 pub use error::Error;

src/sync/crossbeam.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 #[cfg(feature = "sync-crossbeam")]
-use crate::sync::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
+use crate::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
 use crate::types;
 use arc_swap::ArcSwap;
 use crossbeam_channel;

src/sync/flume.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 #[cfg(feature = "sync-flume")]
-use crate::sync::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
+use crate::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
 use crate::types;
 use arc_swap::ArcSwap;
 use flume;

src/sync/std.rs

@@ -1,6 +1,6 @@
 use arc_swap::ArcSwap;
 
-use crate::sync::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
+use crate::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
 use crate::types;
 use std::sync::Arc;
 #[cfg(feature = "sync-std")]
@@ -77,7 +77,7 @@ impl<T> StdSuck<T> {
 mod tests {
     use super::*;
     use crate::Error;
-    use crate::sync::traits::ChannelType;
+    use crate::traits::ChannelType;
     use std::thread;
 
     #[derive(Debug)]

src/sync/traits.rs

@@ -1,23 +1 @@
-pub use crate::error::Error as ChannelError;
-
-pub trait ChannelSender<T> {
-    fn send(&self, msg: T) -> Result<(), ChannelError>;
-}
-
-pub trait ChannelReceiver<T> {
-    fn recv(&self) -> Result<T, ChannelError>;
-}
-
-pub trait ChannelType {
-    type Sender<T>: ChannelSender<T>;
-    type Receiver<T>: ChannelReceiver<T>;
-
-    fn create_request_channel() -> (
-        Self::Sender<crate::types::Request>,
-        Self::Receiver<crate::types::Request>,
-    );
-    fn create_response_channel<T>() -> (
-        Self::Sender<crate::types::Response<T>>,
-        Self::Receiver<crate::types::Response<T>>,
-    );
-}
+pub use crate::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};

src/traits.rs

@@ -0,0 +1,23 @@
+pub use crate::error::Error as ChannelError;
+
+pub trait ChannelSender<T> {
+    fn send(&self, msg: T) -> Result<(), ChannelError>;
+}
+
+pub trait ChannelReceiver<T> {
+    fn recv(&self) -> Result<T, ChannelError>;
+}
+
+pub trait ChannelType {
+    type Sender<T>: ChannelSender<T>;
+    type Receiver<T>: ChannelReceiver<T>;
+
+    fn create_request_channel() -> (
+        Self::Sender<crate::types::Request>,
+        Self::Receiver<crate::types::Request>,
+    );
+    fn create_response_channel<T>() -> (
+        Self::Sender<crate::types::Response<T>>,
+        Self::Receiver<crate::types::Response<T>>,
+    );
+}