From 72ff5ab9bb09b879dc0994906cf096ad0097e235 Mon Sep 17 00:00:00 2001
From: Albert Esteve <aesteve@redhat.com>
Date: Tue, 23 Jan 2024 17:02:19 +0100
Subject: [PATCH] Allow a single retry with wrong msg_type

Getters may fail as the VehicleService sends
messages periodically, and the expected message
with the value may not be the first one to be received.

To fix it, allow one retry. One should be enough
in most cases. The downside of this is that the
unexpected message is discarded. Therefore,
getters shall be used with care.

Alternatively, we could have getters that
discharge the responsibility of processing
the response to users.

Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
 src/lib.rs | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index d5f160e..c118c19 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -329,8 +329,7 @@ impl Vhal {
 
     pub fn get_gear_selection(&self) -> Result<c::VehicleGear> {
         self.get_property(VehicleProperty::GEAR_SELECTION, 0)?;
-        let resp = self.recv_cmd()?;
-        resp.is_valid(VehicleHalProto::MsgType::GET_PROPERTY_RESP)?;
+        let resp = self.recv_retry()?;
 
         Ok(c::VehicleGear::try_from(resp.expect_i32()?)
             .map_err(|_| VhalError::ReceiveMessageValueError)?)
@@ -343,8 +342,8 @@ impl Vhal {
 
     pub fn get_vehicle_speed(&self) -> Result<f32> {
         self.get_property(VehicleProperty::PERF_VEHICLE_SPEED, 0)?;
-        let resp = self.recv_cmd()?;
-        resp.is_valid(VehicleHalProto::MsgType::GET_PROPERTY_RESP)?;
+        let resp = self.recv_retry()?;
+
         resp.expect_f32()
     }
 
@@ -355,8 +354,8 @@ impl Vhal {
 
     pub fn get_vehicle_display_speed(&self) -> Result<f32> {
         self.get_property(VehicleProperty::PERF_VEHICLE_SPEED_DISPLAY, 0)?;
-        let resp = self.recv_cmd()?;
-        resp.is_valid(VehicleHalProto::MsgType::GET_PROPERTY_RESP)?;
+        let resp = self.recv_retry()?;
+
         resp.expect_f32()
     }
 
@@ -427,6 +426,17 @@ impl Vhal {
 
         Ok(msg)
     }
+
+    fn recv_retry(&self) -> Result<EmulatorMessage> {
+        let mut resp = self.recv_cmd()?;
+        if resp.is_valid(VehicleHalProto::MsgType::GET_PROPERTY_RESP).is_err() {
+            // Allow a single retry.
+            resp = self.recv_cmd()?;
+            resp.is_valid(VehicleHalProto::MsgType::GET_PROPERTY_RESP)?;
+        }
+
+        Ok(resp)
+    }
 }
 
 #[cfg(test)]