Add initial modbus plugin

Cargo.toml

@@ -3,11 +3,13 @@ members = [
   "crates/msr",
   "crates/msr-core",
   "crates/msr-legacy",
-  "crates/msr-plugin"
+  "crates/msr-plugin",
+  "crates/msr-plugin-fieldbus-modbus"
 ]
 
 [patch.crates-io]
 msr = { path = "crates/msr" }
 msr-core = { path = "crates/msr-core" }
 msr-legacy = { path = "crates/msr-legacy" }
 msr-plugin = { path = "crates/msr-plugin" }
+msr-plugin-fieldbus-modbus = { path = "crates/msr-plugin-fieldbus-modbus" }

crates/msr-core/Cargo.toml

@@ -14,7 +14,7 @@ thiserror = "1"
 anyhow = { version = "1", optional = true }
 bs58 = { version = "0.4", optional = true }
 csv = { version = "1", optional = true }
-serde = { version = "1", optional = true }
+serde = { version = "1", optional = true, features = ["derive"] }
 serde_json = { version = "1", optional = true }
 uuid = { version = "0.8", optional = true }
 

crates/msr-plugin-fieldbus-modbus/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "msr-plugin-fieldbus-modbus"
+version = "0.0.0"
+edition = "2018"
+
+[dependencies]
+log = "0.4"
+msr-core = { path = "../msr-core" }
+msr-plugin = { path = "../msr-plugin" }
+thiserror = "1"
+tokio = { version = "1", default_features = false, features = ["sync", "macros"] }
+tokio-modbus = "0.5"

crates/msr-plugin-fieldbus-modbus/src/api.rs

@@ -0,0 +1,17 @@
+use std::net::SocketAddr;
+
+#[derive(Debug)]
+pub enum Message {
+    Connect(ConnCfg),
+    Shutdown,
+}
+
+#[derive(Debug)]
+pub enum ConnCfg {
+    Tcp(SocketAddr),
+}
+
+#[derive(Debug, Clone)]
+pub enum Event {
+    ConnectionError(String),
+}

crates/msr-plugin-fieldbus-modbus/src/internal.rs

@@ -0,0 +1,69 @@
+use crate::api::{ConnCfg, Event, Message};
+use msr_plugin::MessageLoop;
+use tokio::sync::{broadcast, mpsc};
+
+#[derive(Default)]
+pub struct Context {
+    conn: Connection,
+}
+
+enum Connection {
+    Disconnected,
+    Connecting,
+    Connected(tokio_modbus::client::Context),
+}
+
+impl Default for Connection {
+    fn default() -> Self {
+        Self::Disconnected
+    }
+}
+
+pub fn create_message_loop(
+    event_tx: broadcast::Sender<Event>,
+) -> (MessageLoop, mpsc::UnboundedSender<Message>) {
+    let mut ctx = Context::default();
+    let (message_tx, mut message_rx) = mpsc::unbounded_channel();
+    let message_loop = async move {
+        log::debug!("Entering modbus plugin message loop");
+        loop {
+            tokio::select! {
+                next_msg = message_rx.recv() => {
+                    if let Some(msg) = next_msg {
+                    log::debug!("Received message: {:?}", msg);
+                    match msg {
+                        Message::Connect(cfg) => {
+                            match cfg {
+                              ConnCfg::Tcp(addr) => {
+                                ctx.conn = Connection::Connecting;
+                                // TODO send event
+                                match tokio_modbus::client::tcp::connect(addr).await {
+                                  Ok(mb_ctx) => {
+                                    ctx.conn = Connection::Connected(mb_ctx);
+                                    // TODO send event
+                                  }
+                                  Err(err) => {
+                                    let ev = Event::ConnectionError(err.to_string());
+                                    if let Err(ev) = event_tx.send(ev) {
+                                      log::debug!("No subscribers, dropping event: {:?}", ev);
+                                    }
+                                  }
+                                }
+                              }
+                            }
+                        }
+                        Message::Shutdown => {
+                          break;
+                        }
+                    }
+                } else {
+                    log::debug!("All message senders have been dropped");
+                    break;
+                }
+                }
+            }
+        }
+        log::debug!("Exiting modbus plugin message loop");
+    };
+    (Box::pin(message_loop), message_tx)
+}

crates/msr-plugin-fieldbus-modbus/src/lib.rs

@@ -0,0 +1,44 @@
+use msr_plugin::MessageLoop;
+use thiserror::Error;
+use tokio::sync::{broadcast, mpsc};
+
+mod api;
+mod internal;
+
+pub use api::*;
+
+pub struct Plugin {
+    message_loop: MessageLoop,
+    message_tx: mpsc::UnboundedSender<Message>,
+    broadcast_tx: broadcast::Sender<Event>,
+}
+
+#[derive(Debug, Error)]
+pub enum SetupError {}
+
+impl Plugin {
+    pub fn setup() -> Result<Self, SetupError> {
+        let (broadcast_tx, _) = broadcast::channel(100);
+        let event_tx = broadcast_tx.clone();
+        let (message_loop, message_tx) = internal::create_message_loop(event_tx);
+        Ok(Self {
+            message_tx,
+            message_loop,
+            broadcast_tx,
+        })
+    }
+}
+
+impl msr_plugin::Plugin for Plugin {
+    type Message = Message;
+    type Event = Event;
+    fn message_sender(&self) -> mpsc::UnboundedSender<Self::Message> {
+        self.message_tx.clone()
+    }
+    fn subscribe_events(&self) -> broadcast::Receiver<Self::Event> {
+        self.broadcast_tx.subscribe()
+    }
+    fn run(self) -> MessageLoop {
+        self.message_loop
+    }
+}