feat: add multiple channel providers

Each provider is enabled via a feature flag.
The currently implemented providers are:
- std::mpsc
- flume
- crossbeam_channel

src/sync/std.rs

@@ -0,0 +1,220 @@
+use crate::sync::traits::{ChannelError, ChannelReceiver, ChannelSender, ChannelType};
+use crate::types;
+#[cfg(feature = "sync-std")]
+use std::sync::mpsc;
+
+type StdSucker<T> = crate::Sucker<T, StdSender<types::Request>, StdReceiver<types::Response<T>>>;
+type StdSourcer<T> = crate::Sourcer<T, StdReceiver<types::Request>, StdSender<types::Response<T>>>;
+
+/// Internal sender type for std backend
+pub struct StdSender<T>(mpsc::Sender<T>);
+/// Internal receiver type for std backend
+pub struct StdReceiver<T>(mpsc::Receiver<T>);
+
+impl<T> ChannelSender<T> for StdSender<T> {
+    fn send(&self, msg: T) -> Result<(), ChannelError> {
+        self.0
+            .send(msg)
+            .map_err(|_| ChannelError::ProducerDisconnected)
+    }
+}
+
+impl<T> ChannelReceiver<T> for StdReceiver<T> {
+    fn recv(&self) -> Result<T, ChannelError> {
+        self.0
+            .recv()
+            .map_err(|_| ChannelError::ProducerDisconnected)
+    }
+}
+
+/// Internal channel type for std backend
+pub struct StdChannel;
+
+impl ChannelType for StdChannel {
+    type Sender<T> = StdSender<T>;
+    type Receiver<T> = StdReceiver<T>;
+
+    fn create_request_channel() -> (Self::Sender<types::Request>, Self::Receiver<types::Request>) {
+        let (tx, rx) = mpsc::channel();
+        (StdSender(tx), StdReceiver(rx))
+    }
+
+    fn create_response_channel<T>() -> (
+        Self::Sender<types::Response<T>>,
+        Self::Receiver<types::Response<T>>,
+    ) {
+        let (tx, rx) = mpsc::channel();
+        (StdSender(tx), StdReceiver(rx))
+    }
+}
+
+pub struct StdSuck<T> {
+    _phantom: std::marker::PhantomData<T>,
+}
+
+impl<T> StdSuck<T> {
+    pub fn pair() -> (StdSucker<T>, StdSourcer<T>)
+    where
+        T: Clone + Send + 'static,
+    {
+        let (request_tx, request_rx) = StdChannel::create_request_channel();
+        let (response_tx, response_rx) = StdChannel::create_response_channel::<T>();
+
+        let state = std::sync::Arc::new(std::sync::Mutex::new(crate::types::ChannelState {
+            source: crate::types::ValueSource::None,
+            closed: false,
+        }));
+
+        let sucker = crate::Sucker {
+            request_tx,
+            response_rx,
+            closed: std::sync::Mutex::new(false),
+            _phantom: std::marker::PhantomData,
+        };
+
+        let sourcer = crate::Sourcer {
+            request_rx,
+            response_tx,
+            state: std::sync::Arc::clone(&state),
+            _phantom: std::marker::PhantomData,
+        };
+
+        (sucker, sourcer)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::Error;
+    use std::thread;
+
+    #[test]
+    fn test_pre_computed_value() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        // Start producer
+        let producer_handle = thread::spawn(move || {
+            sourcer.set_static(42).unwrap();
+            sourcer.run().unwrap();
+        });
+
+        // Ensure consumer gets the value
+        let value = sucker.get().unwrap();
+        assert_eq!(value, 42);
+
+        // Close consumer
+        sucker.close().unwrap();
+
+        producer_handle.join().unwrap();
+    }
+
+    #[test]
+    fn test_closure_value() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        // Start producer
+        let producer_handle = std::thread::spawn(move || {
+            let counter = std::sync::Arc::new(std::sync::Mutex::new(0));
+            let counter_clone = std::sync::Arc::clone(&counter);
+            sourcer
+                .set(move || {
+                    let mut count = counter_clone.lock().unwrap();
+                    *count += 1;
+                    *count
+                })
+                .unwrap();
+            sourcer.run().unwrap();
+        });
+
+        // Ensure consumer gets the value
+        let value1 = sucker.get().unwrap();
+        assert_eq!(value1, 1);
+
+        // Ensure consumer gets the next value
+        let value2 = sucker.get().unwrap();
+        assert_eq!(value2, 2);
+
+        // Close consumer
+        sucker.close().unwrap();
+
+        producer_handle.join().unwrap();
+    }
+
+    #[test]
+    fn test_no_source_error() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        // Start producer
+        let producer_handle = thread::spawn(move || {
+            sourcer.run().unwrap();
+        });
+
+        // Consumer should get NoSource error
+        let result = sucker.get();
+        assert!(matches!(result, Err(Error::NoSource)));
+
+        // Close consumer
+        sucker.close().unwrap();
+
+        producer_handle.join().unwrap();
+    }
+
+    #[test]
+    fn test_channel_closed_error() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        // Start producer
+        let producer_handle = thread::spawn(move || {
+            sourcer.set_static(42).unwrap();
+            sourcer.run().unwrap();
+        });
+
+        // Close consumer
+        sucker.close().unwrap();
+
+        let result = sucker.get();
+        assert!(matches!(result, Err(Error::ChannelClosed)));
+
+        producer_handle.join().unwrap();
+    }
+
+    #[test]
+    fn test_producer_disconnection_error() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        // Start producer
+        let producer_handle = thread::spawn(move || {
+            sourcer.set_static(42).unwrap();
+            // Simulate crash
+            panic!("Producer crashed!");
+        });
+
+        let result = sucker.get();
+        assert!(matches!(result, Err(Error::ProducerDisconnected)));
+
+        let _ = producer_handle.join();
+    }
+
+    #[test]
+    fn test_is_closed() {
+        let (sucker, sourcer) = StdSuck::<i32>::pair();
+
+        assert!(!sucker.is_closed());
+
+        // Start producer
+        let producer_handle = thread::spawn(move || {
+            sourcer.set_static(42).unwrap();
+            sourcer.run().unwrap();
+        });
+
+        // Get one value
+        let _ = sucker.get().unwrap();
+        assert!(!sucker.is_closed());
+
+        // Close and check
+        sucker.close().unwrap();
+
+        producer_handle.join().unwrap();
+    }
+}