Better Messenger recv-related docs and names

apps/magpie/src/protocol.rs

@@ -172,7 +172,11 @@ impl<T: Write, I, O: Serialize> Messenger<T, I, O> {
 }
 
 impl<T: Read, I: DeserializeOwned, O> Messenger<T, I, O> {
-    /// Receives all pending messages and queues them for [recv].
+    /// Synchronously receives all pending messages and queues them for [recv].
+    ///
+    /// This function only works if the transport is in non-blocking mode.
+    /// Otherwise, this may block while waiting for more data, even if the
+    /// data it receives does not add up to a full message.
     pub fn flush_recv(&mut self) -> std::io::Result<()> {
         let mut buf = [0u8; 1024];
 
@@ -199,7 +203,10 @@ impl<T: Read, I: DeserializeOwned, O> Messenger<T, I, O> {
     }
 
     /// Tries to receive a single input packet.
-    pub fn recv(&mut self) -> Option<I> {
+    ///
+    /// For messages to be received here, [flush_recv] must be called to
+    /// continuously read pending data from the transport.
+    pub fn try_recv(&mut self) -> Option<I> {
         self.queue.recv()
     }
 }
@@ -211,16 +218,16 @@ mod async_messages {
     use std::marker::Unpin;
 
     impl<T: AsyncReadExt + Unpin, I: DeserializeOwned, O: Serialize> Messenger<T, I, O> {
-        pub async fn recv_async(&mut self) -> std::io::Result<I> {
+        pub async fn recv(&mut self) -> std::io::Result<I> {
             let mut buf = [0u8; 1024];
 
             loop {
-                let num = self.transport.read(&mut buf).await?;
-                self.queue.on_data(&buf[..num]);
-
                 if let Some(msg) = self.queue.recv() {
                     return Ok(msg);
                 }
+
+                let num = self.transport.read(&mut buf).await?;
+                self.queue.on_data(&buf[..num])?;
             }
         }
     }

apps/magpie/src/service/ipc.rs

@@ -94,7 +94,7 @@ impl Client {
             eprintln!("flush_recv() error: {:?}", err);
         }
 
-        while let Some(msg) = self.messenger.recv() {
+        while let Some(msg) = self.messenger.try_recv() {
             println!("Client #{}: {:?}", self.token.0, msg);
             match msg {
                 MagpieServerMsg::CreatePanel(CreatePanel {