feat: enable use of tokio-console with diagnostics.tracing setting

View real-time tokio diagnostics by setting the configuration option
"diagnostics.tracing" to true.

src/config.rs

@@ -64,6 +64,12 @@ pub struct Authorization {
     pub pubkey_whitelist: Option<Vec<String>>, // If present, only allow these pubkeys to publish events
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[allow(unused)]
+pub struct Diagnostics {
+    pub tracing: bool, // enables tokio console-subscriber
+}
+
 #[derive(Serialize, Deserialize, PartialEq, Debug, Clone, Copy)]
 #[serde(rename_all = "lowercase")]
 pub enum VerifiedUsersMode {
@@ -122,6 +128,7 @@ impl VerifiedUsers {
 #[allow(unused)]
 pub struct Settings {
     pub info: Info,
+    pub diagnostics: Diagnostics,
     pub database: Database,
     pub network: Network,
     pub limits: Limits,
@@ -181,6 +188,7 @@ impl Default for Settings {
                 pubkey: None,
                 contact: None,
             },
+            diagnostics: Diagnostics { tracing: false },
             database: Database {
                 data_directory: ".".to_owned(),
                 in_memory: false,

src/main.rs

@@ -8,6 +8,8 @@ use std::sync::mpsc as syncmpsc;
 use std::sync::mpsc::{Receiver as MpscReceiver, Sender as MpscSender};
 use std::thread;
 
+use console_subscriber::ConsoleLayer;
+
 /// Return a requested DB name from command line arguments.
 fn db_from_args(args: Vec<String>) -> Option<String> {
     if args.len() == 3 && args.get(1) == Some(&"--db".to_owned()) {
@@ -28,6 +30,12 @@ fn main() -> Result<(), Error> {
     // configure settings from config.toml
     // replace default settings with those read from config.toml
     let mut settings = config::Settings::new();
+
+    if settings.diagnostics.tracing {
+        // enable tracing with tokio-console
+        ConsoleLayer::builder().with_default_env().init();
+    }
+
     // update with database location
     if let Some(db) = db_dir {
         settings.database.data_directory = db;

src/server.rs

@@ -282,6 +282,9 @@ pub fn start_server(settings: Settings, shutdown_rx: MpscReceiver<()>) -> Result
         });
         // listen for ctrl-c interruupts
         let ctrl_c_shutdown = invoke_shutdown.clone();
+        // listener for webserver shutdown
+        let webserver_shutdown_listen = invoke_shutdown.subscribe();
+
         tokio::spawn(async move {
             tokio::signal::ctrl_c().await.unwrap();
             info!("shutting down due to SIGINT (main)");
@@ -321,11 +324,10 @@ pub fn start_server(settings: Settings, shutdown_rx: MpscReceiver<()>) -> Result
                 }))
             }
         });
-        let shutdown_listen = invoke_shutdown.subscribe();
         let server = Server::bind(&socket_addr)
             .serve(make_svc)
-            .with_graceful_shutdown(ctrl_c_or_signal(shutdown_listen));
-        // run hyper
+            .with_graceful_shutdown(ctrl_c_or_signal(webserver_shutdown_listen));
+        // run hyper in this thread.  This is why the thread does not return.
         if let Err(e) = server.await {
             eprintln!("server error: {}", e);
         }