p2p: Major refactoring of the handshake protocol

Introduce a new protocol InitProtocol which can be used as the core protocol
for initializing a connection with a peer.
Move the handshake logic from the PeerPool module to the protocols directory and
build a handshake protocol that implements InitProtocol trait.

2 files changed, 47 insertions, 14 deletions

diff --git a/core/src/error.rs b/core/src/error.rs
index 2b8f641..754feb5 100644
--- a/core/src/error.rs
+++ b/core/src/error.rs
@@ -16,6 +16,9 @@ pub enum Error {
     #[error("Path Not Found Error: {0}")]
     PathNotFound(&'static str),
 
+    #[error("Event Emit Error: {0}")]
+    EventEmitError(String),
+
     #[cfg(feature = "crypto")]
     #[error(transparent)]
     Ed25519(#[from] ed25519_dalek::ed25519::Error),
diff --git a/core/src/event.rs b/core/src/event.rs
index a4e356b..709dbd9 100644
--- a/core/src/event.rs
+++ b/core/src/event.rs
@@ -10,7 +10,7 @@ use chrono::{DateTime, Utc};
 use futures_util::stream::{FuturesUnordered, StreamExt};
 use log::{debug, error};
 
-use crate::{async_runtime::lock::Mutex, util::random_32, Result};
+use crate::{async_runtime::lock::Mutex, util::random_32, Error, Result};
 
 const CHANNEL_BUFFER_SIZE: usize = 1000;
 
@@ -111,13 +111,17 @@ where
     ///
     /// The event must implement the [`EventValueTopic`] trait to indicate the
     /// topic of the event. Otherwise, you can use `emit_by_topic()`.
-    pub async fn emit<E: EventValueTopic<Topic = T> + Clone>(&self, value: &E) {
+    pub async fn emit<E: EventValueTopic<Topic = T> + Clone>(&self, value: &E) -> Result<()> {
         let topic = E::topic();
-        self.emit_by_topic(&topic, value).await;
+        self.emit_by_topic(&topic, value).await
     }
 
     /// Emits an event to the listeners.
-    pub async fn emit_by_topic<E: EventValueAny + EventValue + Clone>(&self, topic: &T, value: &E) {
+    pub async fn emit_by_topic<E: EventValueAny + EventValue + Clone>(
+        &self,
+        topic: &T,
+        value: &E,
+    ) -> Result<()> {
         let value: Arc<dyn EventValueAny> = Arc::new(value.clone());
         let event = Event::new(value);
 
@@ -128,7 +132,10 @@ where
                 "Failed to emit an event to a non-existent topic {:?}",
                 topic
             );
-            return;
+            return Err(Error::EventEmitError(format!(
+                "Emit an event to a non-existent topic {:?}",
+                topic,
+            )));
         }
 
         let event_ids = topics.get_mut(topic).unwrap();
@@ -136,7 +143,10 @@ where
 
         if !event_ids.contains_key(&event_id) {
             debug!("Failed to emit an event: unknown event id {:?}", event_id);
-            return;
+            return Err(Error::EventEmitError(format!(
+                "Emit an event: unknown event id {}",
+                event_id,
+            )));
         }
 
         let mut results = FuturesUnordered::new();
@@ -159,6 +169,8 @@ where
         for listener_id in failed_listeners.iter() {
             listeners.remove(listener_id);
         }
+
+        Ok(())
     }
 
     /// Registers a new event listener for the given topic.
@@ -166,10 +178,10 @@ where
         self: &Arc<Self>,
         topic: &T,
     ) -> EventListener<T, E> {
-        let chan = async_channel::bounded(self.listener_buffer_size);
-
         let topics = &mut self.listeners.lock().await;
 
+        let chan = async_channel::bounded(self.listener_buffer_size);
+
         if !topics.contains_key(topic) {
             topics.insert(topic.clone(), HashMap::new());
         }
@@ -197,6 +209,16 @@ where
         listener
     }
 
+    /// Remove all topics and event listeners  
+    pub async fn clear(self: &Arc<Self>) {
+        self.listeners.lock().await.clear();
+    }
+
+    /// Unregisters all event listeners for the given topic.
+    pub async fn unregister_topic(self: &Arc<Self>, topic: &T) {
+        self.listeners.lock().await.remove(topic);
+    }
+
     /// Removes the event listener attached to the given topic.
     async fn remove(&self, topic: &T, event_id: &str, listener_id: &EventListenerID) {
         let topics = &mut self.listeners.lock().await;
@@ -419,10 +441,12 @@ mod tests {
 
             event_sys
                 .emit_by_topic(&Topic::TopicA, &A { a_value: 3 })
-                .await;
+                .await
+                .expect("Emit event");
             event_sys
                 .emit_by_topic(&Topic::TopicB, &B { b_value: 5 })
-                .await;
+                .await
+                .expect("Emit event");
 
             let msg = a_listener.recv().await.unwrap();
             assert_eq!(msg, A { a_value: 3 });
@@ -434,13 +458,17 @@ mod tests {
             let c_listener = event_sys.register::<C>(&Topic::TopicC).await;
             let d_listener = event_sys.register::<C>(&Topic::TopicD).await;
 
-            event_sys.emit(&C { c_value: 10 }).await;
+            event_sys
+                .emit(&C { c_value: 10 })
+                .await
+                .expect("Emit event");
             let msg = c_listener.recv().await.unwrap();
             assert_eq!(msg, C { c_value: 10 });
 
             event_sys
                 .emit_by_topic(&Topic::TopicD, &C { c_value: 10 })
-                .await;
+                .await
+                .expect("Emit event");
             let msg = d_listener.recv().await.unwrap();
             assert_eq!(msg, C { c_value: 10 });
 
@@ -450,14 +478,16 @@ mod tests {
 
             event_sys
                 .emit_by_topic(&Topic::TopicE, &E { e_value: 5 })
-                .await;
+                .await
+                .expect("Emit event");
 
             let msg = e_listener.recv().await.unwrap();
             assert_eq!(msg, E { e_value: 5 });
 
             event_sys
                 .emit_by_topic(&Topic::TopicE, &F { f_value: 5 })
-                .await;
+                .await
+                .expect("Emit event");
 
             let msg = f_listener.recv().await.unwrap();
             assert_eq!(msg, F { f_value: 5 });