Add event handler

Signed-off-by: trivernis <trivernis@protonmail.com>

Cargo.toml

@@ -10,4 +10,5 @@ edition = "2018"
 rmp = "0.8.9"
 rmp-serde = "0.14.4"
 serde = {version = "1.0.117", features = ["serde_derive"]}
-byteorder = "1.3.4"
+byteorder = "1.3.4"
+parking_lot = "0.11.0"

src/event_handler/mod.rs

@@ -0,0 +1,49 @@
+use crate::event::Event;
+use serde::de::DeserializeOwned;
+use serde::Serialize;
+use std::collections::HashMap;
+
+#[cfg(test)]
+mod tests;
+
+/// A handler for events
+pub struct EventHandler<T> {
+    event_handlers: HashMap<String, Vec<Box<dyn Fn(&Event<T>)>>>,
+}
+
+impl<T> EventHandler<T>
+where
+    T: Serialize + DeserializeOwned,
+{
+    /// Creates a new vented event_handler
+    pub fn new() -> Self {
+        Self {
+            event_handlers: HashMap::new(),
+        }
+    }
+
+    /// Adds a handler for the given event
+    pub fn on<F: 'static>(&mut self, event_name: &str, handler: F)
+    where
+        F: Fn(&Event<T>),
+    {
+        match self.event_handlers.get_mut(event_name) {
+            Some(handlers) => handlers.push(Box::new(handler)),
+            None => {
+                self.event_handlers
+                    .insert(event_name.to_string(), vec![Box::new(handler)]);
+            }
+        }
+    }
+
+    /// Handles a single event
+    pub fn handle_event(&mut self, event: Event<T>) -> bool {
+        if let Some(handlers) = self.event_handlers.get(&event.name) {
+            handlers.iter().for_each(|handler| handler(&event));
+
+            true
+        } else {
+            false
+        }
+    }
+}

src/event_handler/tests.rs

@@ -0,0 +1,28 @@
+use crate::event::Event;
+use crate::event_handler::EventHandler;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+#[test]
+fn it_handles_events() {
+    let mut handler = EventHandler::new();
+    let call_count = Arc::new(AtomicUsize::new(0));
+    {
+        let call_count = Arc::clone(&call_count);
+        handler.on("test", move |_event| {
+            call_count.fetch_add(1, Ordering::Relaxed);
+        });
+    }
+    {
+        let call_count = Arc::clone(&call_count);
+        handler.on("test2", move |_event| {
+            call_count.fetch_add(1, Ordering::Relaxed);
+        })
+    }
+
+    handler.handle_event(Event::new("test".to_string()));
+    handler.handle_event(Event::new("test".to_string()));
+    handler.handle_event(Event::new("test2".to_string()));
+
+    assert_eq!(call_count.load(Ordering::Relaxed), 3)
+}

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod event;
-pub mod result;
+pub mod event_handler;
+pub mod result;