fix: Query online, remove loop retry (#9326)

Signed-off-by: fufesou <linlong1266@gmail.com>

src/flutter.rs

@@ -2057,18 +2057,18 @@ pub mod sessions {
 pub(super) mod async_tasks {
     use hbb_common::{
         bail,
-        tokio::{
-            self, select,
-            sync::mpsc::{unbounded_channel, UnboundedSender},
-        },
+        tokio::{self, select},
         ResultType,
     };
     use std::{
         collections::HashMap,
-        sync::{Arc, Mutex},
+        sync::{
+            mpsc::{sync_channel, SyncSender},
+            Arc, Mutex,
+        },
     };
 
-    type TxQueryOnlines = UnboundedSender<Vec<String>>;
+    type TxQueryOnlines = SyncSender<Vec<String>>;
     lazy_static::lazy_static! {
         static ref TX_QUERY_ONLINES: Arc<Mutex<Option<TxQueryOnlines>>> = Default::default();
     }
@@ -2085,20 +2085,18 @@ pub(super) mod async_tasks {
 
     #[tokio::main(flavor = "current_thread")]
     async fn start_flutter_async_runner_() {
-        let (tx_onlines, mut rx_onlines) = unbounded_channel::<Vec<String>>();
+        // Only one task is allowed to run at the same time.
+        let (tx_onlines, rx_onlines) = sync_channel::<Vec<String>>(1);
         TX_QUERY_ONLINES.lock().unwrap().replace(tx_onlines);
 
         loop {
-            select! {
-                ids = rx_onlines.recv() => {
-                    match ids {
-                        Some(_ids) => {
-                            crate::client::peer_online::query_online_states(_ids, handle_query_onlines).await
-                        }
-                        None => {
-                            break;
-                        }
-                    }
+            match rx_onlines.recv() {
+                Ok(ids) => {
+                    crate::client::peer_online::query_online_states(ids, handle_query_onlines).await
+                }
+                _ => {
+                    // unreachable!
+                    break;
                 }
             }
         }
@@ -2106,7 +2104,8 @@ pub(super) mod async_tasks {
 
     pub fn query_onlines(ids: Vec<String>) -> ResultType<()> {
         if let Some(tx) = TX_QUERY_ONLINES.lock().unwrap().as_ref() {
-            let _ = tx.send(ids)?;
+            // Ignore if the channel is full.
+            let _ = tx.try_send(ids)?;
         } else {
             bail!("No tx_query_onlines");
         }