From: Greg Burri <greg.burri@gmail.com>
Date: Sat, 21 Oct 2023 19:43:04 +0000 (+0200)
Subject: Retry when a 'WouldBlock' error
X-Git-Url: https://git.euphorik.ch/?a=commitdiff_plain;h=ab7d0d4d2ed7680e777d71217d65d9e9b340349d;p=stakingWatchdogWatchdog.git

Retry when a 'WouldBlock' error
is given by socket recv function
---

diff --git a/src/main.rs b/src/main.rs
index c7791a0..c854c74 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -111,37 +111,45 @@ enum PingError {
 }
 
 fn ping(socket: &UdpSocket, rng: &mut ThreadRng) -> std::result::Result<Duration, PingError> {
-    let number: u64 = rng.gen();
-    let mut buffer = number.to_le_bytes();
-
-    let now = time::Instant::now();
-    match socket.send(&buffer) {
-        Ok(_size_sent) => {
-            buffer.fill(0);
-            match socket.recv(&mut buffer) {
-                Ok(size_received) => {
-                    if size_received == 8 {
-                        let number_received = u64::from_le_bytes(buffer);
-                        if number_received != number {
+    loop {
+        let number: u64 = rng.gen();
+        let mut buffer = number.to_le_bytes();
+        let now = time::Instant::now();
+        match socket.send(&buffer) {
+            Ok(_size_sent) => {
+                buffer.fill(0);
+                match socket.recv(&mut buffer) {
+                    Ok(size_received) => {
+                        if size_received == 8 {
+                            let number_received = u64::from_le_bytes(buffer);
+                            if number_received == number {
+                                return Ok(time::Instant::now() - now);
+                            } else {
+                                return Err(PingError::WrongMessageReceived(format!(
+                                    "Message number receceived ({}) is not equal to the one sent ({})",
+                                    number_received, number
+                                )));
+                            }
+                        } else {
                             return Err(PingError::WrongMessageReceived(format!(
-                                "Message number receceived ({}) is not equal to the one sent ({})",
-                                number_received, number
+                                "Size of packet must be 8, received size: {}",
+                                size_received
                             )));
                         }
-                    } else {
-                        return Err(PingError::WrongMessageReceived(format!(
-                            "Size of packet must be 8, received size: {}",
-                            size_received
-                        )));
                     }
+                    // FIXME.
+                    // Test the kind because sometime 'recv' returns
+                    // '(Os { code: 11, kind: WouldBlock, message: "Resource temporarily unavailable" }'.
+                    // Try again in this case.
+                    Err(error) if error.kind() == std::io::ErrorKind::WouldBlock => {
+                        println!("WouldBlock error: {}", error)
+                    }
+                    Err(error) => return Err(PingError::SocketReceiveError(error)),
                 }
-                Err(error) => return Err(PingError::SocketReceiveError(error)),
             }
+            Err(error) => return Err(PingError::SocketSendError(error)),
         }
-        Err(error) => return Err(PingError::SocketSendError(error)),
     }
-
-    Ok(time::Instant::now() - now)
 }
 
 fn send_email(title: &str, body: &str, login: &str, pass: &str) -> Result<()> {