i think mio would still be good here

Cargo.lock

@@ -485,9 +485,11 @@ dependencies = [
  "humantime",
  "lazy_static",
  "log",
+ "mio",
  "num_enum",
  "satrs",
  "satrs-mib",
+ "socket2",
  "strum",
  "thiserror",
  "toml",

Cargo.toml

@@ -16,6 +16,8 @@ strum = { version = "0.26", features = ["derive"] }
 thiserror = "1"
 derive-new = "0.6"
 num_enum = "0.7"
+mio = "0.8"
+socket2 = "0.5"
 
 [dependencies.satrs]
 version = "0.2.0-rc.3"

pytmtc/common.py

@@ -7,6 +7,7 @@ import struct
 
 EXPERIMENT_ID = 278
 EXPERIMENT_APID = 1024 + EXPERIMENT_ID
+TCP_SERVER_PORT = 4096
 
 
 class EventSeverity(enum.IntEnum):

pytmtc/main.py

@@ -18,7 +18,7 @@ from spacepackets.ccsds.time import CdsShortTimestamp
 from tmtccmd import TcHandlerBase, ProcedureParamsWrapper
 from tmtccmd.core.base import BackendRequest
 from tmtccmd.pus import VerificationWrapper
-from tmtccmd.tmtc import CcsdsTmHandler, GenericApidHandlerBase, TelemetryListT
+from tmtccmd.tmtc import CcsdsTmHandler, GenericApidHandlerBase
 from tmtccmd.com import ComInterface
 from tmtccmd.config import (
     CmdTreeNode,
@@ -44,13 +44,12 @@ from tmtccmd.tmtc import (
     QueueWrapper,
 )
 from spacepackets.seqcount import FileSeqCountProvider, PusFileSeqCountProvider
+from tcp_server import TcpServer
 from tmtccmd.util.obj_id import ObjectIdDictT
-from collections import deque
-import socket
 
 
 import pus_tc
-from common import EXPERIMENT_APID, EventU32
+from common import EXPERIMENT_APID, EventU32, TCP_SERVER_PORT
 
 _LOGGER = logging.getLogger()
 
@@ -68,6 +67,10 @@ class SatRsConfigHook(HookBase):
         assert self.cfg_path is not None
         packet_id_list = []
         packet_id_list.append(PacketId(PacketType.TM, True, EXPERIMENT_APID))
+        if com_if_key == "tcp_server":
+            tcp_server = TcpServer(TCP_SERVER_PORT)
+            return tcp_server
+        else:
             cfg = create_com_interface_cfg_default(
                 com_if_key=com_if_key,
                 json_cfg_path=self.cfg_path,

pytmtc/tcp_server.py

@@ -1,4 +1,6 @@
 from typing import Any, Optional
+import select
+import time
 import socket
 import logging
 from threading import Thread, Event, Lock
@@ -16,6 +18,7 @@ class TcpServer(ComInterface):
         self.port = port
         self._max_num_packets_in_tc_queue = 500
         self._max_num_packets_in_tm_queue = 500
+        self._default_timeout_secs = 0.5
         self._server_addr = ("localhost", self.port)
         self._tc_packet_queue = deque()
         self._tm_packet_queue = deque()
@@ -23,8 +26,11 @@ class TcpServer(ComInterface):
         self._tm_lock = Lock()
         self._kill_signal = Event()
         self._server_socket: Optional[socket.socket] = None
-        self._server_thread = Thread(target=TcpServer._server_task, daemon=True)
+        self._server_thread = Thread(target=self._server_task, daemon=True)
         self._connected = False
+        self._conn_start = None
+        self._writing_done = False
+        self._reading_done = False
 
     @property
     def connected(self) -> bool:
@@ -47,31 +53,44 @@ class TcpServer(ComInterface):
         """
         if self.connected:
             return
-        self.server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        # We need to check the kill signal periodically to allow closing the server.
-        self.server_socket.settimeout(0.5)
-        self.server_socket.bind(self._server_addr)
         self._connected = True
         self._server_thread.start()
 
     def _server_task(self):
-        assert self._server_socket is not None
+        self._server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        while True and not self._kill_signal.is_set():
+        self._server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        # We need to check the kill signal periodically to allow closing the server.
+        self._server_socket.settimeout(self._default_timeout_secs)
+        self._server_socket.bind(self._server_addr)
         self._server_socket.listen()
+        while True and not self._kill_signal.is_set():
+            try:
                 (conn_socket, conn_addr) = self._server_socket.accept()
-            _LOGGER.info("TCP client {} connected", conn_addr)
+                self.conn_start = time.time()
                 while True:
-                bytes_recvd = conn_socket.recv(4096)
+                    self._handle_connection(conn_socket, conn_addr)
-                if len(bytes_recvd) > 0:
+                    if (
-                    print(f"Received bytes from TCP client: {bytes_recvd.decode()}")
+                        self._reading_done and self._writing_done
-                    with self._tm_lock:
+                    ) or time.time() - self.conn_start > 0.5:
-                        self._tm_packet_queue.append(bytes_recvd)
+                        print("reading and writing done")
-                elif len(bytes_recvd) == 0:
                         break
-                else:
+            except TimeoutError:
-                    print("error receiving data from TCP client")
+                print("timeout error")
+                continue
 
+    def _handle_connection(self, conn_socket: socket.socket, conn_addr: Any):
+        _LOGGER.info(f"TCP client {conn_addr} connected")
+        (readable, writable, _) = select.select(
+            [conn_socket],
+            [conn_socket],
+            [],
+            0.1,
+        )
+
+        # TODO: Why is the stupid conn socket never readable?
+        print(f"Writable: {writable}")
+        print(f"Readable: {readable}")
+        if writable and writable[0]:
             queue_len = 0
             with self._tc_lock:
                 queue_len = len(self._tc_packet_queue)
@@ -79,8 +98,23 @@ class TcpServer(ComInterface):
                 next_packet = bytes()
                 with self._tc_lock:
                     next_packet = self._tc_packet_queue.popleft()
+                if len(next_packet) > 0:
                     conn_socket.sendall(next_packet)
                 queue_len -= 1
+            self._writing_done = True
+        if readable and readable[0]:
+            print("reading shit")
+            while True:
+                bytes_recvd = conn_socket.recv(4096)
+                if len(bytes_recvd) > 0:
+                    print(f"Received bytes from TCP client: {bytes_recvd.decode()}")
+                    with self._tm_lock:
+                        self._tm_packet_queue.append(bytes_recvd)
+                elif len(bytes_recvd) == 0:
+                    self._reading_done = True
+                    break
+                else:
+                    print("error receiving data from TCP client")
 
     def is_open(self) -> bool:
         """Can be used to check whether the communication interface is open. This is useful if
@@ -103,7 +137,6 @@ class TcpServer(ComInterface):
         :raises SendError: Sending failed for some reason.
         """
         with self._tc_lock:
-            # Deque is thread-safe according to the documentation.. so this should be fine.
             if len(self._tc_packet_queue) >= self._max_num_packets_in_tc_queue:
                 # Remove oldest packet
                 self._tc_packet_queue.popleft()

src/interface/tcp_spp_client.rs

@@ -1,25 +1,20 @@
 use std::io::{self, Read, Write};
 use std::net::{IpAddr, Ipv4Addr, SocketAddr};
 use std::sync::mpsc;
-use std::time::Duration;
 
-use ops_sat_rs::config::SPP_CLIENT_WIRETAPPING_RX;
+use mio::net::TcpStream;
+use mio::{Events, Interest, Poll, Token};
+use ops_sat_rs::config::tasks::STOP_CHECK_FREQUENCY;
+use ops_sat_rs::config::{SPP_CLIENT_WIRETAPPING_RX, TCP_SPP_SERVER_PORT};
 use satrs::encoding::ccsds::parse_buffer_for_ccsds_space_packets;
 use satrs::queue::GenericSendError;
 use satrs::spacepackets::PacketId;
 use satrs::tmtc::PacketAsVec;
 use satrs::ComponentId;
-use std::net::TcpStream;
 use thiserror::Error;
 
 use super::{SimpleSpValidator, TcpComponent};
 
-#[derive(Debug)]
-pub enum ConnectionResult {
-    Connected(TcpStream),
-    Timeout,
-}
-
 #[derive(Debug, Error)]
 pub enum ClientError {
     #[error("send error: {0}")]
@@ -30,6 +25,10 @@ pub enum ClientError {
 
 pub struct TcpSppClient {
     id: ComponentId,
+    poll: Poll,
+    events: Events,
+    // Optional to allow periodic reconnection attempts on the TCP server.
+    client: TcpStream,
     read_buf: [u8; 4096],
     tm_tcp_client_rx: mpsc::Receiver<PacketAsVec>,
     server_addr: SocketAddr,
@@ -45,9 +44,20 @@ impl TcpSppClient {
         valid_ids: &'static [PacketId],
         port: u16,
     ) -> io::Result<Self> {
+        let poll = Poll::new()?;
+        let events = Events::with_capacity(128);
         let server_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), port);
+        let mut client = TcpStream::connect(server_addr)?;
+        poll.registry().register(
+            &mut client,
+            Token(0),
+            Interest::READABLE | Interest::WRITABLE,
+        )?;
         Ok(Self {
             id,
+            poll,
+            events,
+            client,
             read_buf: [0; 4096],
             server_addr,
             tm_tcp_client_rx,
@@ -56,59 +66,65 @@ impl TcpSppClient {
         })
     }
 
-    pub fn attempt_connection(
+    pub fn periodic_operation(&mut self) -> Result<(), ClientError> {
-        &mut self,
+        // if self.client.is_some() {
-        timeout: Duration,
+        return self.perform_regular_operation();
-    ) -> Result<ConnectionResult, ClientError> {
+        /*
-        match TcpStream::connect_timeout(&self.server_addr, timeout) {
+        } else {
-            Ok(client) => Ok(ConnectionResult::Connected(client)),
+            log::info!("attempting reconnect");
-            Err(e) => {
+            let client_result = self.attempt_connection();
-                if e.kind() == io::ErrorKind::WouldBlock || e.kind() == io::ErrorKind::TimedOut {
+            match client_result {
-                    return Ok(ConnectionResult::Timeout);
+                Ok(_) => {
+                    self.perform_regular_operation()?;
                 }
-                Err(e.into())
+                Err(ref e) => {
+                    log::warn!(
+                        "connection to TCP server {} failed: {}",
+                        self.server_addr,
+                        e
+                    );
                 }
             }
         }
-
+        */
-    pub fn operation(&mut self, timeout: Duration) {
-        match self.attempt_connection(timeout) {
-            Ok(result) => {
-                if let ConnectionResult::Connected(mut client) = result {
-                    if let Err(e) = self.handle_client_operation(&mut client) {
-                        log::error!("error handling TCP client operation: {}", e)
-                    }
-                    drop(client);
-                    std::thread::sleep(timeout);
-                }
-            }
-            Err(e) => {
-                log::error!("TCP client error: {}", e);
-            }
-        }
-    }
-
-    pub fn handle_client_operation(&mut self, client: &mut TcpStream) -> Result<(), ClientError> {
-        self.write_to_server(client)?;
-        client.shutdown(std::net::Shutdown::Write)?;
-        self.read_from_server(client)?;
         Ok(())
     }
 
-    pub fn read_from_server(&mut self, client: &mut TcpStream) -> Result<(), ClientError> {
+    pub fn perform_regular_operation(&mut self) -> Result<(), ClientError> {
-        match client.read(&mut self.read_buf) {
+        self.poll
-            Ok(0) => (),
+            .poll(&mut self.events, Some(STOP_CHECK_FREQUENCY))?;
+        let events: Vec<mio::event::Event> = self.events.iter().cloned().collect();
+        for event in events {
+            if event.token() == Token(0) {
+                if event.is_readable() {
+                    log::info!("readable event");
+                    self.check_conn_status()?;
+                    self.read_from_server()?;
+                }
+                if event.is_writable() {
+                    log::info!("writable event");
+                    self.check_conn_status()?;
+                    self.write_to_server()?;
+                }
+            }
+        }
+        Ok(())
+    }
+
+    pub fn read_from_server(&mut self) -> Result<(), ClientError> {
+        match self.client.read(&mut self.read_buf) {
+            Ok(0) => (), // return Err(io::Error::from(io::ErrorKind::BrokenPipe).into()),
             Ok(read_bytes) => self.handle_read_bytstream(read_bytes)?,
             Err(e) => return Err(e.into()),
         }
         Ok(())
     }
 
-    pub fn write_to_server(&mut self, client: &mut TcpStream) -> io::Result<()> {
+    pub fn write_to_server(&mut self) -> io::Result<()> {
         loop {
             match self.tm_tcp_client_rx.try_recv() {
                 Ok(tm) => {
-                    client.write_all(&tm.packet)?;
+                    self.client.write_all(&tm.packet)?;
                 }
                 Err(e) => match e {
                     mpsc::TryRecvError::Empty => break,
@@ -122,6 +138,18 @@ impl TcpSppClient {
         Ok(())
     }
 
+    pub fn check_conn_status(&mut self) -> io::Result<bool> {
+        match self.client.peer_addr() {
+            Ok(_) => Ok(true),
+            Err(e) => {
+                if e.kind() == io::ErrorKind::NotConnected {
+                    return Ok(false);
+                }
+                Err(e)
+            }
+        }
+    }
+
     pub fn handle_read_bytstream(&mut self, read_bytes: usize) -> Result<(), ClientError> {
         let mut dummy = 0;
         if SPP_CLIENT_WIRETAPPING_RX {

src/main.rs

@@ -232,7 +232,10 @@ fn main() {
         .spawn(move || {
             info!("Running TCP SPP client");
             loop {
-                tcp_spp_client.operation(STOP_CHECK_FREQUENCY);
+                let result = tcp_spp_client.periodic_operation();
+                if let Err(e) = result {
+                    log::error!("TCP SPP client error: {}", e);
+                }
                 if tcp_client_stop_signal.load(std::sync::atomic::Ordering::Relaxed) {
                     break;
                 }