Add a global channel for new event advertisement (stores event offsets)

src/globals.rs

@@ -3,6 +3,7 @@ use crate::store::Store;
 use hyper::server::conn::Http;
 use lazy_static::lazy_static;
 use std::sync::OnceLock;
+use tokio::sync::broadcast::Sender;
 use tokio::sync::RwLock;
 
 pub struct Globals {
@@ -10,6 +11,12 @@ pub struct Globals {
     pub store: OnceLock<Store>,
     pub http_server: Http,
     pub rid: OnceLock<String>,
+
+    /// This is a broadcast channel where new incoming events are advertised by their offset.
+    /// Every handler needs to listen to it and check if the incoming event matches any
+    /// subscribed fitlers for their client, and if so, send the event to their client under
+    /// that subscription.
+    pub new_events: Sender<usize>,
 }
 
 lazy_static! {
@@ -18,11 +25,14 @@ lazy_static! {
         http_server.http1_only(true);
         http_server.http1_keep_alive(true);
 
+        let (sender, _) = tokio::sync::broadcast::channel(512);
+
         Globals {
             config: RwLock::new(FriendlyConfig::default().into_config().unwrap()),
             store: OnceLock::new(),
             http_server,
             rid: OnceLock::new(),
+            new_events: sender,
         }
     };
 }