Change emit to return an async value

Signed-off-by: trivernis <trivernis@protonmail.com>

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "vented"
 description = "Event driven encrypted tcp communicaton"
-version = "0.8.1"
+version = "0.9.0"
 authors = ["trivernis <trivernis@protonmail.com>"]
 edition = "2018"
 readme = "README.md"

src/server/data.rs

@@ -1,5 +1,6 @@
 use crate::crypto::CryptoStream;
 use crate::event_handler::EventHandler;
+use crate::result::VentedError;
 use crate::WaitGroup;
 use crypto_box::SecretKey;
 use executors::crossbeam_workstealing_pool;
@@ -28,43 +29,88 @@ pub(crate) struct ServerConnectionContext {
     pub known_nodes: Arc<Mutex<HashMap<String, Node>>>,
     pub event_handler: Arc<Mutex<EventHandler>>,
     pub connections: Arc<Mutex<HashMap<String, CryptoStream>>>,
-    pub forwarded_connections: Arc<Mutex<HashMap<(String, String), AsyncValue<CryptoStream>>>>,
+    pub forwarded_connections: Arc<Mutex<HashMap<(String, String), AsyncValue<CryptoStream, ()>>>>,
     pub pool: crossbeam_workstealing_pool::ThreadPool<DynParker>,
+    pub redirect_handles: Arc<Mutex<HashMap<[u8; 16], AsyncValue<(), VentedError>>>>,
 }
 
-#[derive(Clone)]
+pub struct AsyncValue<T, E> {
-pub struct AsyncValue<T> {
     value: Arc<Mutex<Option<T>>>,
+    error: Arc<Mutex<Option<E>>>,
     wg: Option<WaitGroup>,
 }
 
-impl<T> AsyncValue<T> {
+impl<V, E> AsyncValue<V, E>
+where
+    E: std::fmt::Display,
+{
     /// Creates the future with no value
     pub fn new() -> Self {
         Self {
             value: Arc::new(Mutex::new(None)),
+            error: Arc::new(Mutex::new(None)),
             wg: Some(WaitGroup::new()),
         }
     }
 
+    /// Creates a new AsyncValue with an already resolved value
+    pub fn with_value(value: V) -> Self {
+        Self {
+            value: Arc::new(Mutex::new(Some(value))),
+            error: Arc::new(Mutex::new(None)),
+            wg: None,
+        }
+    }
+
+    pub fn with_error(error: E) -> Self {
+        Self {
+            value: Arc::new(Mutex::new(None)),
+            error: Arc::new(Mutex::new(Some(error))),
+            wg: None,
+        }
+    }
+
     /// Sets the value of the future consuming the wait group
-    pub fn set_value(&mut self, value: T) {
+    pub fn resolve(&mut self, value: V) {
         self.value.lock().replace(value);
         mem::take(&mut self.wg);
     }
 
+    /// Sets an error for the value
+    pub fn reject(&mut self, error: E) {
+        self.error.lock().replace(error);
+        mem::take(&mut self.wg);
+    }
+
+    pub fn result(&mut self, result: Result<V, E>) {
+        match result {
+            Ok(v) => self.resolve(v),
+            Err(e) => self.reject(e),
+        }
+    }
+
+    pub fn block_unwrap(&mut self) -> V {
+        match self.get_value() {
+            Ok(v) => v,
+            Err(e) => panic!("Unwrap on Err value: {}", e),
+        }
+    }
+
     /// Returns the value of the future after it has been set.
     /// This call blocks
-    #[allow(dead_code)]
+    pub fn get_value(&mut self) -> Result<V, E> {
-    pub fn get_value(&mut self) -> T {
         if let Some(wg) = mem::take(&mut self.wg) {
             wg.wait();
         }
-        self.value.lock().take().unwrap()
+        if let Some(err) = self.error.lock().take() {
+            Err(err)
+        } else {
+            Ok(self.value.lock().take().unwrap())
+        }
     }
 
     /// Returns the value of the future only blocking for the given timeout
-    pub fn get_value_with_timeout(&mut self, timeout: Duration) -> Option<T> {
+    pub fn get_value_with_timeout(&mut self, timeout: Duration) -> Option<Result<V, E>> {
         let start = Instant::now();
 
         while self.value.lock().is_none() {
@@ -73,6 +119,22 @@ impl<T> AsyncValue<T> {
                 break;
             }
         }
-        self.value.lock().take()
+        if let Some(err) = self.error.lock().take() {
+            Some(Err(err))
+        } else if let Some(value) = self.value.lock().take() {
+            Some(Ok(value))
+        } else {
+            None
+        }
+    }
+}
+
+impl<T, E> Clone for AsyncValue<T, E> {
+    fn clone(&self) -> Self {
+        Self {
+            value: Arc::clone(&self.value),
+            error: Arc::clone(&self.error),
+            wg: self.wg.clone(),
+        }
     }
 }

src/server/mod.rs

@@ -31,7 +31,7 @@ pub mod server_events;
 
 pub(crate) const CRATE_VERSION: &str = env!("CARGO_PKG_VERSION");
 
-type ForwardFutureVector = Arc<Mutex<HashMap<(String, String), AsyncValue<CryptoStream>>>>;
+type ForwardFutureVector = Arc<Mutex<HashMap<(String, String), AsyncValue<CryptoStream, ()>>>>;
 type CryptoStreamMap = Arc<Mutex<HashMap<String, CryptoStream>>>;
 
 /// The vented server that provides parallel handling of connections
@@ -64,7 +64,7 @@ type CryptoStreamMap = Arc<Mutex<HashMap<String, CryptoStream>>>;
 ///    
 ///    None    // the return value is the response event Option<Event>
 /// });
-/// assert!(server.emit("B".to_string(), Event::new("ping".to_string())).is_err()) // this won't work without a known node B
+/// assert!(server.emit("B".to_string(), Event::new("ping".to_string())).get_value().is_err()) // this won't work without a known node B
 /// ```
 pub struct VentedServer {
     connections: CryptoStreamMap,
@@ -74,7 +74,7 @@ pub struct VentedServer {
     event_handler: Arc<Mutex<EventHandler>>,
     global_secret_key: SecretKey,
     node_id: String,
-    redirect_handles: Arc<Mutex<HashMap<[u8; 16], AsyncValue<bool>>>>,
+    redirect_handles: Arc<Mutex<HashMap<[u8; 16], AsyncValue<(), VentedError>>>>,
 }
 
 impl VentedServer {
@@ -122,22 +122,34 @@ impl VentedServer {
     /// Emits an event to the specified Node
     /// The actual writing is done in a separate thread from the thread pool.
     /// With the returned wait group one can wait for the event to be written.
-    pub fn emit(&self, node_id: String, event: Event) -> VentedResult<()> {
+    pub fn emit(&self, node_id: String, event: Event) -> AsyncValue<(), VentedError> {
-        if let Ok(stream) = self.get_connection(&node_id) {
+        let future = AsyncValue::new();
+
+        self.pool.execute({
+            let mut future = AsyncValue::clone(&future);
+            let context = self.get_server_context();
+            move || {
+
+                if let Ok(stream) = Self::get_connection(context.clone(), &node_id) {
                     if let Err(e) = stream.send(event) {
                         log::error!("Failed to send event: {}", e);
-                self.connections.lock().remove(stream.receiver_node());
+                        context.connections.lock().remove(stream.receiver_node());
 
-                return Err(e);
+                        future.reject(e);
+                    } else {
+                        future.resolve(());
                     }
                 } else {
                     log::trace!(
                         "Trying to redirect the event to a different node to be sent to target node..."
                     );
-            self.send_event_redirected(node_id, event)?;
+                    let result = Self::send_event_redirected(context.clone(), node_id, event);
+                    future.result(result);
+                }
             }
+        });
 
-        Ok(())
+        future
     }
 
     /// Adds a handler for the given event.
@@ -195,12 +207,17 @@ impl VentedServer {
             event_handler: Arc::clone(&self.event_handler),
             pool: self.pool.clone(),
             forwarded_connections: Arc::clone(&self.forwarded_connections),
+            redirect_handles: Arc::clone(&self.redirect_handles),
         }
     }
 
     /// Tries to send an event redirected by emitting a redirect event to all public nodes
-    fn send_event_redirected(&self, target: String, event: Event) -> VentedResult<()> {
+    fn send_event_redirected(
-        let public_nodes = self
+        context: ServerConnectionContext,
+        target: String,
+        event: Event,
+    ) -> VentedResult<()> {
+        let public_nodes = context
             .known_nodes
             .lock()
             .values()
@@ -209,29 +226,28 @@ impl VentedServer {
             .collect::<Vec<Node>>();
         for node in public_nodes {
             let payload = RedirectPayload::new(
-                self.node_id.clone(),
+                context.node_id.clone(),
                 node.id.clone(),
                 target.clone(),
                 event.clone().as_bytes(),
             );
             let mut future = AsyncValue::new();
-            self.redirect_handles
+            context
+                .redirect_handles
                 .lock()
                 .insert(payload.id, AsyncValue::clone(&future));
 
-            if let Ok(stream) = self.get_connection(&node.id) {
+            if let Ok(stream) = Self::get_connection(context.clone(), &node.id) {
                 if let Err(e) = stream.send(Event::with_payload(REDIRECT_EVENT, &payload)) {
                     log::error!("Failed to send event: {}", e);
-                    self.connections.lock().remove(stream.receiver_node());
+                    context.connections.lock().remove(stream.receiver_node());
                 }
             }
 
-            if let Some(value) = future.get_value_with_timeout(Duration::from_secs(1)) {
+            if let Some(Ok(_)) = future.get_value_with_timeout(Duration::from_secs(1)) {
-                if value {
                 return Ok(());
             }
         }
-        }
 
         Err(VentedError::UnreachableNode(target))
     }
@@ -286,34 +302,35 @@ impl VentedServer {
     /// Takes three attempts to retrieve a connection for the given node.
     /// First it tries to use the already established connection stored in the shared connections vector.
     /// If that fails it tries to establish a new connection to the node by using the known address
-    fn get_connection(&self, target: &String) -> VentedResult<CryptoStream> {
+    fn get_connection(
+        context: ServerConnectionContext,
+        target: &String,
+    ) -> VentedResult<CryptoStream> {
         log::trace!("Trying to connect to {}", target);
-        if let Some(stream) = self.connections.lock().get(target) {
+
+        if let Some(stream) = context.connections.lock().get(target) {
             log::trace!("Reusing existing connection.");
+
             return Ok(CryptoStream::clone(stream));
         }
 
-        let target_node = {
+        let target_node = context
-            self.known_nodes
+            .known_nodes
             .lock()
             .get(target)
             .cloned()
-                .ok_or(VentedError::UnknownNode(target.clone()))?
+            .ok_or(VentedError::UnknownNode(target.clone()))?;
-        };
+
         if let Some(address) = target_node.address {
             log::trace!("Connecting to known address");
-            match self.connect(address) {
-                Ok(stream) => {
-                    return Ok(stream);
-                }
-                Err(e) => log::error!("Failed to connect to node '{}': {}", target, e),
-            }
-        }
 
+            Self::connect(context, address)
+        } else {
             log::trace!("All direct connection attempts to {} failed", target);
 
             Err(VentedError::UnreachableNode(target.clone()))
         }
+    }
 
     /// Establishes a crypto stream for the given stream
     fn get_crypto_stream(
@@ -337,17 +354,20 @@ impl VentedServer {
     }
 
     /// Connects to the given address as a tcp client
-    fn connect(&self, address: String) -> VentedResult<CryptoStream> {
+    fn connect(
+        mut context: ServerConnectionContext,
+        address: String,
+    ) -> VentedResult<CryptoStream> {
         let stream = TcpStream::connect(address)?;
-        let mut context = self.get_server_context();
         context.is_server = false;
 
         let connections = Arc::clone(&context.connections);
-        let stream = Self::get_crypto_stream(context.clone(), stream)?;
+        let pool = context.pool.clone();
+        let event_handler = Arc::clone(&context.event_handler);
+        let stream = Self::get_crypto_stream(context, stream)?;
 
-        self.pool.execute({
+        pool.execute({
             let stream = CryptoStream::clone(&stream);
-            let event_handler = Arc::clone(&self.event_handler);
 
             move || {
                 event_handler.lock().handle_event(Event::new(READY_EVENT));

src/server/server_events.rs

@@ -1,4 +1,5 @@
 use crate::event::Event;
+use crate::result::VentedError;
 use crate::server::data::Node;
 use crate::server::VentedServer;
 use executors::Executor;
@@ -103,7 +104,7 @@ impl VentedServer {
             move |event| {
                 let payload = event.get_payload::<RedirectResponsePayload>().ok()?;
                 let mut future = redirect_handles.lock().remove(&payload.id)?;
-                future.set_value(true);
+                future.resolve(());
 
                 None
             }
@@ -113,7 +114,7 @@ impl VentedServer {
             move |event| {
                 let payload = event.get_payload::<RedirectResponsePayload>().ok()?;
                 let mut future = redirect_handles.lock().remove(&payload.id)?;
-                future.set_value(false);
+                future.reject(VentedError::Rejected);
 
                 None
             }

tests/test_communication.rs

@@ -91,21 +91,21 @@ fn test_server_communication() {
     });
     server_b
         .emit("A".to_string(), Event::new(NODE_LIST_REQUEST_EVENT))
-        .unwrap();
+        .block_unwrap();
     server_c
         .emit("A".to_string(), Event::new("ping".to_string()))
-        .unwrap();
+        .block_unwrap();
     for _ in 0..9 {
         server_b
             .emit("A".to_string(), Event::new("ping".to_string()))
-            .unwrap();
+            .block_unwrap();
     }
     server_a
         .emit("B".to_string(), Event::new("pong".to_string()))
-        .unwrap();
+        .block_unwrap();
     server_b
         .emit("C".to_string(), Event::new("ping".to_string()))
-        .unwrap();
+        .block_unwrap();
 
     // wait one second to make sure the servers were able to process the events
     for _ in 0..100 {