extract frontend crate (#186)

lan-mouse-ipc/src/connect.rs

@@ -0,0 +1,89 @@
+use crate::{ConnectionError, FrontendEvent, FrontendRequest, IpcError};
+use std::{
+    cmp::min,
+    io::{self, prelude::*, BufReader, LineWriter, Lines},
+    thread,
+    time::Duration,
+};
+
+#[cfg(unix)]
+use std::os::unix::net::UnixStream;
+
+#[cfg(windows)]
+use std::net::TcpStream;
+
+pub struct FrontendEventReader {
+    #[cfg(unix)]
+    lines: Lines<BufReader<UnixStream>>,
+    #[cfg(windows)]
+    lines: Lines<BufReader<TcpStream>>,
+}
+
+pub struct FrontendRequestWriter {
+    #[cfg(unix)]
+    line_writer: LineWriter<UnixStream>,
+    #[cfg(windows)]
+    line_writer: LineWriter<TcpStream>,
+}
+
+impl FrontendEventReader {
+    pub fn next_event(&mut self) -> Option<Result<FrontendEvent, IpcError>> {
+        match self.lines.next()? {
+            Err(e) => Some(Err(e.into())),
+            Ok(l) => Some(serde_json::from_str(l.as_str()).map_err(|e| e.into())),
+        }
+    }
+}
+
+impl FrontendRequestWriter {
+    pub fn request(&mut self, request: FrontendRequest) -> Result<(), io::Error> {
+        let mut json = serde_json::to_string(&request).unwrap();
+        log::debug!("requesting: {json}");
+        json.push('\n');
+        self.line_writer.write_all(json.as_bytes())?;
+        Ok(())
+    }
+}
+
+pub fn connect() -> Result<(FrontendEventReader, FrontendRequestWriter), ConnectionError> {
+    let rx = wait_for_service()?;
+    let tx = rx.try_clone()?;
+    let buf_reader = BufReader::new(rx);
+    let lines = buf_reader.lines();
+    let line_writer = LineWriter::new(tx);
+    let reader = FrontendEventReader { lines };
+    let writer = FrontendRequestWriter { line_writer };
+    Ok((reader, writer))
+}
+
+/// wait for the lan-mouse socket to come online
+#[cfg(unix)]
+fn wait_for_service() -> Result<UnixStream, ConnectionError> {
+    let socket_path = crate::default_socket_path()?;
+    let mut duration = Duration::from_millis(10);
+    loop {
+        if let Ok(stream) = UnixStream::connect(&socket_path) {
+            break Ok(stream);
+        }
+        // a signaling mechanism or inotify could be used to
+        // improve this
+        thread::sleep(exponential_back_off(&mut duration));
+    }
+}
+
+#[cfg(windows)]
+fn wait_for_service() -> Result<TcpStream, ConnectionError> {
+    let mut duration = Duration::from_millis(10);
+    loop {
+        if let Ok(stream) = TcpStream::connect("127.0.0.1:5252") {
+            break Ok(stream);
+        }
+        thread::sleep(exponential_back_off(&mut duration));
+    }
+}
+
+fn exponential_back_off(duration: &mut Duration) -> Duration {
+    let new = duration.saturating_mul(2);
+    *duration = min(new, Duration::from_secs(1));
+    *duration
+}