fix: use just one socket, not two sockets as Nikola suggested

i(alexander) wasn't sure if it can work well bidirectionally,
but it seems it's ok

Author: alehander92

src/db-backend/src/rr_dispatcher.rs

@@ -26,8 +26,7 @@ pub struct CtRRWorker {
     pub ct_rr_worker_exe: PathBuf,
     pub rr_trace_folder: PathBuf,
     process: Option<Child>,
-    sending_stream: Option<UnixStream>,
-    receiving_stream: Option<UnixStream>,
+    stream: Option<UnixStream>,
 }
 
 #[derive(Default)]
@@ -44,8 +43,7 @@ impl CtRRWorker {
             ct_rr_worker_exe: PathBuf::from(ct_rr_worker_exe),
             rr_trace_folder: PathBuf::from(rr_trace_folder),
             process: None,
-            sending_stream: None,
-            receiving_stream: None,
+            stream: None,
         }
     }
 
@@ -78,29 +76,11 @@ impl CtRRWorker {
 
         let run_id = std::process::id() as usize;
 
-        // sending socket:
-        let sending_socket_path = ct_rr_worker_socket_path("backend", &self.name, run_id)?;
-        info!(
-            "try to connect to worker with sending socket in {}",
-            sending_socket_path.display()
-        );
-        loop {
-            if let Ok(sending_stream) = UnixStream::connect(&sending_socket_path) {
-                self.sending_stream = Some(sending_stream);
-                break;
-            }
-            thread::sleep(Duration::from_millis(1));
-            // TODO: handle different kinds of errors
-        }
-        // receiving socket:
-        let receiving_socket_path = ct_rr_worker_socket_path("worker", &self.name, run_id)?;
-        info!(
-            "try to connect to worker with receiving socket in {}",
-            receiving_socket_path.display()
-        );
+        let socket_path = ct_rr_worker_socket_path("", &self.name, run_id)?;
+        info!("try to connect to worker with socket in {}", socket_path.display());
         loop {
-            if let Ok(receiving_stream) = UnixStream::connect(&receiving_socket_path) {
-                self.receiving_stream = Some(receiving_stream);
+            if let Ok(stream) = UnixStream::connect(&socket_path) {
+                self.stream = Some(stream);
                 break;
             }
             thread::sleep(Duration::from_millis(1));
@@ -115,16 +95,16 @@ impl CtRRWorker {
         let raw_json = serde_json::to_string(&query)?;
 
         info!("send to worker {raw_json}\n");
-        self.sending_stream
+        self.stream
             .as_mut()
             .expect("valid sending stream")
             .write(&format!("{raw_json}\n").into_bytes())?;
 
         let mut res = "".to_string();
         info!("wait to read");
 
-        let mut reader = BufReader::new(self.receiving_stream.as_mut().expect("valid receiving stream"));
-        reader.read_line(&mut res)?;
+        let mut reader = BufReader::new(self.stream.as_mut().expect("valid receiving stream"));
+        reader.read_line(&mut res)?; // TODO: more robust reading/read all
 
         res = String::from(res.trim()); // trim newlines/whitespace!