Chapter.10 미션 추가

- Mission B: Busy-waiting non-blocking server

Co-authored-by: famo1245 <kandallee38@gmail.com>

chapter10/README.md

@@ -99,3 +99,105 @@ Wrong number of pizzas, please try again
 12
 Thank you for ordering 12 pizzas!
 ```
+
+# Mission B: Busy-waiting non-blocking server
+### Description
+Implement the Python code below in Java
+
+### Python Code
+```python
+#!/usr/bin/env python3.9
+
+"""Busy-waiting non-blocking server implementation"""
+
+import typing as T
+from socket import socket, create_server
+
+# the maximum amount of data to be received at once
+BUFFER_SIZE = 1024
+ADDRESS = ("127.0.0.1", 12345)   # address and port of the host machine
+
+
+class Server:
+    clients: T.Set[socket] = set()
+
+    def __init__(self) -> None:
+        try:
+            print(f"Starting up at: {ADDRESS}")
+            self.server_socket = create_server(ADDRESS)
+            # set socket to non-blocking mode
+            self.server_socket.setblocking(False)
+        except OSError:
+            self.server_socket.close()
+            print("\nServer stopped.")
+
+    def accept(self) -> None:
+        try:
+            conn, address = self.server_socket.accept()
+            print(f"Connected to {address}")
+            # making this connection non-blocking
+            conn.setblocking(False)
+            self.clients.add(conn)
+        except BlockingIOError:
+            # [Errno 35] Resource temporarily unavailable
+            # indicates that "accept" returned without results
+            pass
+
+    def serve(self, conn: socket) -> None:
+        """Serve the incoming connection by sending and receiving data."""
+        try:
+            while True:
+                data = conn.recv(BUFFER_SIZE)
+                if not data:
+                    break
+                try:
+                    order = int(data.decode())
+                    response = f"Thank you for ordering {order} pizzas!\n"
+                except ValueError:
+                    response = "Wrong number of pizzas, please try again\n"
+                print(f"Sending message to {conn.getpeername()}")
+                # send a response
+                conn.send(response.encode())
+        except BlockingIOError:
+            # recv/send returns without data
+            pass
+
+    def start(self) -> None:
+        """Start the server by continuously accepting and serving incoming
+        connections."""
+        print("Server listening for incoming connections")
+        try:
+            while True:
+                self.accept()
+                for conn in self.clients.copy():
+                    self.serve(conn)
+        finally:
+            self.server_socket.close()
+            print("\nServer stopped.")
+
+
+if __name__ == "__main__":
+    server = Server()
+    server.start()
+```
+
+### Sample Output
+#### Server
+```
+Starting up at: ('127.0.0.1', 12345)
+Server listening for incoming connections
+Connected to ('127.0.0.1', 57283)
+Sending message to ('127.0.0.1', 57283)
+Sending message to ('127.0.0.1', 57283)
+Sending message to ('127.0.0.1', 57283)
+```
+### Terminal
+```
+nc 127.0.0.1 12345
+a
+Wrong number of pizzas, please try again
+123
+Thank you for ordering 123 pizzas!
+11
+Thank you for ordering 11 pizzas!
+```