prs10: improve serial handling

src/sources/prs10.rs

@@ -1,11 +1,14 @@
 use std::any::type_name;
 use std::str::FromStr;
 use std::sync::Arc;
+use std::time::Duration;
 
 use async_trait::async_trait;
 use bitflags::bitflags;
 use itertools::Itertools;
-use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader, ReadHalf, WriteHalf};
+use tokio::io::{
+    AsyncBufReadExt, AsyncReadExt, AsyncWriteExt, BufReader, BufWriter, ReadHalf, WriteHalf,
+};
 use tokio::select;
 use tokio::sync::OnceCell;
 use tokio::time::{interval, timeout};
@@ -116,6 +119,7 @@ bitflags! {
         const EFC_LOW = (1<<3);
         const CAL_VOLTAGE_HIGH = (1<<4);
         const CAL_VOLTAGE_LOW = (1<<5);
+        const _ = !0;
     }
 }
 
@@ -322,7 +326,7 @@ pub struct Prs10Monitor {
     name: String,
     config: Prs10Config,
     rx: ReadHalf<SerialStream>,
-    tx: WriteHalf<SerialStream>,
+    tx: BufWriter<WriteHalf<SerialStream>>,
     info: OnceCell<Prs10Info>,
 }
 
@@ -333,8 +337,9 @@ impl Prs10Monitor {
 
     #[instrument(level = "debug", skip_all, fields(cmd = String::from_utf8_lossy(cmd).to_string()))]
     pub async fn cmd_response(&mut self, cmd: &[u8]) -> Result<Vec<u8>, std::io::Error> {
-        self.tx.write_all(cmd).await.unwrap();
-        self.tx.write_u8(b'\r').await.unwrap();
+        self.tx.write_all(cmd).await?;
+        self.tx.write_u8(b'\r').await?;
+        self.tx.flush().await?;
         let mut reader = BufReader::new(&mut self.rx);
         let mut buf = Vec::new();
         let read = timeout(self.config.timeout, reader.read_until(b'\r', &mut buf)).await??;
@@ -485,6 +490,20 @@ impl Prs10Monitor {
             }),
         }))
     }
+
+    async fn reset_rx_state(&mut self) -> Result<(), Box<dyn std::error::Error>> {
+        // flush any pending input and potential responses from the receiver side
+        self.tx.write_u8(b'\r').await?;
+        self.tx.flush().await?;
+        let mut discard = vec![];
+        loop {
+            match timeout(Duration::from_millis(100), self.rx.read_buf(&mut discard)).await {
+                Ok(_) => discard.clear(),
+                Err(_) => break,
+            }
+        }
+        Ok(())
+    }
 }
 
 #[async_trait]
@@ -516,8 +535,9 @@ impl ChimemonSource for Prs10Monitor {
             port.name().unwrap(),
             port.baud_rate().unwrap()
         );
-        let (rx, tx) = tokio::io::split(port);
 
+        let (rx, tx) = tokio::io::split(port);
+        let tx = BufWriter::new(tx);
         Self {
             name: name.to_owned(),
             config,