WIP: Epiphany Refactor (#85)

server/src/message_queue.rs

@@ -0,0 +1,76 @@
+use std::collections::HashMap;
+use std::sync::{mpsc, RwLock, Mutex};
+
+use id::{Id, get_id};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "type")]
+pub enum Message {
+    InstanceChanged {
+        id: Id,
+    },
+}
+
+pub struct MessageQueue {
+   messages: RwLock<Vec<Message>>,
+   message_listeners: Mutex<HashMap<Id, mpsc::Sender<()>>>,
+}
+
+impl MessageQueue {
+    pub fn new() -> MessageQueue {
+        MessageQueue {
+            messages: RwLock::new(Vec::new()),
+            message_listeners: Mutex::new(HashMap::new()),
+        }
+    }
+
+    pub fn push_messages(&self, new_messages: &[Message]) {
+        let message_listeners = self.message_listeners.lock().unwrap();
+
+        {
+            let mut messages = self.messages.write().unwrap();
+            messages.extend_from_slice(new_messages);
+        }
+
+        {
+            for listener in message_listeners.values() {
+                listener.send(()).unwrap();
+            }
+        }
+    }
+
+    pub fn subscribe(&self, sender: mpsc::Sender<()>) -> Id {
+        let id = get_id();
+
+        {
+            let mut message_listeners = self.message_listeners.lock().unwrap();
+            message_listeners.insert(id, sender);
+        }
+
+        id
+    }
+
+    pub fn unsubscribe(&self, id: Id) {
+        {
+            let mut message_listeners = self.message_listeners.lock().unwrap();
+            message_listeners.remove(&id);
+        }
+    }
+
+    pub fn get_message_cursor(&self) -> u32 {
+        self.messages.read().unwrap().len() as u32
+    }
+
+    pub fn get_messages_since(&self, cursor: u32) -> (u32, Vec<Message>) {
+        let messages = self.messages.read().unwrap();
+
+        let current_cursor = messages.len() as u32;
+
+        // Cursor is out of bounds or there are no new messages
+        if cursor >= current_cursor {
+            return (current_cursor, Vec::new());
+        }
+
+        (current_cursor, messages[(cursor as usize)..].to_vec())
+    }
+}