devises a strategy for signals

kordophoned/include/net.buzzert.kordophonecd.Server.xml

@@ -4,6 +4,8 @@
     <interface name="net.buzzert.kordophone.Repository">
         <method name="GetVersion">
             <arg type="s" name="version" direction="out" />
+            <annotation name="org.freedesktop.DBus.DocString" 
+                        value="Returns the version of the client daemon."/>
         </method>
 
         <method name="GetConversations">
@@ -21,7 +23,14 @@
         </method>
 
         <method name="SyncAllConversations">
+            <annotation name="org.freedesktop.DBus.DocString" 
+                        value="Initiates a background sync of all conversations with the server."/>
         </method>
+
+        <signal name="ConversationsUpdated">
+            <annotation name="org.freedesktop.DBus.DocString" 
+                        value="Emitted when the list of conversations is updated."/>
+        </signal>
     </interface>
 
     <interface name="net.buzzert.kordophone.Settings">

kordophoned/src/daemon/mod.rs

@@ -4,6 +4,9 @@ use settings::Settings;
 pub mod events;
 use events::*;
 
+pub mod signals;
+use signals::*;
+
 use anyhow::Result;
 use directories::ProjectDirs;
 use std::error::Error;
@@ -57,6 +60,10 @@ mod target {
 pub struct Daemon {
     pub event_sender: Sender<Event>,
     event_receiver: Receiver<Event>,
+
+    signal_receiver: Option<Receiver<Signal>>,
+    signal_sender: Sender<Signal>,
+
     version: String,
     database: Arc<Mutex<Database>>,
     runtime: tokio::runtime::Runtime,
@@ -73,7 +80,7 @@ impl Daemon {
 
         // Create event channels
         let (event_sender, event_receiver) = tokio::sync::mpsc::channel(100);
-
+        let (signal_sender, signal_receiver) = tokio::sync::mpsc::channel(100);
         // Create background task runtime 
         let runtime = tokio::runtime::Builder::new_multi_thread()
             .enable_all()
@@ -82,7 +89,15 @@ impl Daemon {
 
         let database_impl = Database::new(&database_path.to_string_lossy())?;
         let database = Arc::new(Mutex::new(database_impl));
-        Ok(Self { version: "0.1.0".to_string(), database, event_receiver, event_sender, runtime })
+        Ok(Self { 
+            version: "0.1.0".to_string(), 
+            database, 
+            event_receiver, 
+            event_sender, 
+            signal_receiver: Some(signal_receiver),
+            signal_sender, 
+            runtime 
+        })
     }
 
     pub async fn run(&mut self) {
@@ -99,8 +114,9 @@ impl Daemon {
 
             Event::SyncAllConversations(reply) => {
                 let db_clone = self.database.clone();
+                let signal_sender = self.signal_sender.clone();
                 self.runtime.spawn(async move {
-                    let result = Self::sync_all_conversations_impl(db_clone).await;
+                    let result = Self::sync_all_conversations_impl(db_clone, signal_sender).await;
                     if let Err(e) = result {
                         log::error!("Error handling sync event: {}", e);
                     }
@@ -136,11 +152,16 @@ impl Daemon {
         }
     }
 
+    /// Panics if the signal receiver has already been taken. 
+    pub fn obtain_signal_receiver(&mut self) -> Receiver<Signal> { 
+        self.signal_receiver.take().unwrap()
+    }
+
     async fn get_conversations(&mut self) -> Vec<Conversation> {
         self.database.lock().await.with_repository(|r| r.all_conversations().unwrap()).await
     }
 
-    async fn sync_all_conversations_impl(mut database: Arc<Mutex<Database>>) -> Result<()> {
+    async fn sync_all_conversations_impl(mut database: Arc<Mutex<Database>>, signal_sender: Sender<Signal>) -> Result<()> {
         log::info!(target: target::SYNC, "Starting conversation sync");
 
         let mut client = Self::get_client_impl(database.clone()).await?;
@@ -171,6 +192,9 @@ impl Daemon {
             database.with_repository(|r| r.insert_messages(&conversation_id, db_messages)).await?;
         }
 
+        // Send conversations updated signal.
+        signal_sender.send(Signal::ConversationsUpdated).await?;
+
         log::info!(target: target::SYNC, "Synchronized {} conversations", num_conversations);
         Ok(())
     }    

kordophoned/src/daemon/signals.rs

@@ -0,0 +1,4 @@
+#[derive(Debug, Clone)]
+pub enum Signal {
+    ConversationsUpdated,
+}

kordophoned/src/dbus/mod.rs

@@ -8,4 +8,8 @@ pub mod interface {
     pub const OBJECT_PATH: &str = "/net/buzzert/kordophonecd/daemon";
 
     include!(concat!(env!("OUT_DIR"), "/kordophone-server.rs"));
+
+    pub mod signals {
+        pub use crate::interface::NetBuzzertKordophoneRepositoryConversationsUpdated as ConversationsUpdated;
+    }
 }

kordophoned/src/dbus/server_impl.rs

@@ -9,6 +9,7 @@ use crate::daemon::{
     DaemonResult,
     events::{Event, Reply},
     settings::Settings,
+    signals::Signal,
 };
 
 use crate::dbus::interface::NetBuzzertKordophoneRepository as DbusRepository;

kordophoned/src/main.rs

@@ -4,10 +4,9 @@ mod daemon;
 use std::future;
 use log::LevelFilter;
 
-use std::sync::Arc;
-use tokio::sync::Mutex;
-
 use daemon::Daemon;
+use daemon::signals::Signal;
+
 use dbus::endpoint::Endpoint as DbusEndpoint;
 use dbus::interface;
 use dbus::server_impl::ServerImpl;
@@ -35,7 +34,7 @@ async fn main() {
     let server = ServerImpl::new(daemon.event_sender.clone());
 
     // Register DBus interfaces with endpoint
-    let endpoint = DbusEndpoint::new(server.clone());
+    let endpoint = DbusEndpoint::new(server);
     endpoint.register(
         interface::NAME,
         interface::OBJECT_PATH,
@@ -47,6 +46,24 @@ async fn main() {
         }
     ).await;
 
+    let mut signal_receiver = daemon.obtain_signal_receiver();
+    tokio::spawn(async move {
+        use dbus::interface::signals as DbusSignals;
+
+        while let Some(signal) = signal_receiver.recv().await {
+            match signal {
+                Signal::ConversationsUpdated => {
+                    log::info!("Sending signal: ConversationsUpdated");
+                    endpoint.send_signal(interface::OBJECT_PATH, DbusSignals::ConversationsUpdated{})
+                        .unwrap_or_else(|_| {
+                            log::error!("Failed to send signal");
+                            0
+                        });
+                }
+            }
+        }
+    });
+
     daemon.run().await;
 
     future::pending::<()>().await;