feat(grpc): Add basic grpc example

src/grpc.rs

@@ -0,0 +1,37 @@
+use std::error::Error;
+use std::net::{SocketAddr, TcpListener};
+
+use tonic::async_trait;
+
+use self::client::GRPCClient;
+use self::server::GRPCServer;
+
+mod client;
+mod server;
+
+pub mod hello_world {
+    tonic::include_proto!("helloworld");
+}
+
+#[async_trait]
+pub trait Connection {
+    async fn connect(&self) -> Result<(), Box<dyn Error>>;
+}
+
+fn is_socket_in_use(addr: String) -> bool {
+    let socket: SocketAddr = addr.parse().expect("Failed to create socket");
+    match TcpListener::bind(socket) {
+        Ok(_) => true,
+        Err(_) => false,
+    }
+}
+
+pub fn run() -> Result<Box<dyn Connection>, Box<dyn Error>> {
+    let addr = "[::1]:50051";
+
+    if is_socket_in_use(addr.to_string()) {
+        Ok(Box::new(GRPCServer::new(addr.to_string())))
+    } else {
+        Ok(Box::new(GRPCClient::new(addr.to_string())))
+    }
+}