Fix "Address already in use" error on flet run hot reload

sdk/python/packages/flet/src/flet/async_local_socket_connection.py

@@ -7,7 +7,7 @@
 import tempfile
 import threading
 from pathlib import Path
-from typing import List
+from typing import List, Optional
 
 from flet.utils import get_free_tcp_port, is_windows
 from flet_core.local_connection import LocalConnection
@@ -27,18 +27,19 @@ class AsyncLocalSocketConnection(LocalConnection):
     def __init__(
         self,
         port: int = 0,
+        uds_path: Optional[str] = None,
         on_event=None,
         on_session_created=None,
     ):
         super().__init__()
         self.__send_queue = asyncio.Queue(1)
         self.__port = port
+        self.__uds_path = uds_path
         self.__on_event = on_event
         self.__on_session_created = on_session_created
 
     async def connect(self):
         self.__connected = False
-        self.__uds_path = None
         if is_windows() or self.__port > 0:
             # TCP
             host = "localhost"
@@ -49,9 +50,10 @@ async def connect(self):
             self.__server = asyncio.create_task(server.serve_forever())
         else:
             # UDS
-            self.__uds_path = str(
-                Path(tempfile.gettempdir()).joinpath(random_string(10))
-            )
+            if not self.__uds_path:
+                self.__uds_path = str(
+                    Path(tempfile.gettempdir()).joinpath(random_string(10))
+                )
             self.page_url = self.__uds_path
             logging.info(f"Starting up UDS server on {self.__uds_path}")
             server = await asyncio.start_unix_server(
@@ -65,8 +67,8 @@ async def handle_connection(
         if not self.__connected:
             self.__connected = True
             logging.debug("Connected new TCP client")
-            asyncio.create_task(self.__receive_loop(reader))
-            asyncio.create_task(self.__send_loop(writer))
+            self.__receive_loop_task = asyncio.create_task(self.__receive_loop(reader))
+            self.__send_loop_task = asyncio.create_task(self.__send_loop(writer))
 
     async def __receive_loop(self, reader: asyncio.StreamReader):
         while True:
@@ -156,6 +158,10 @@ async def __send(self, message: ClientMessage):
     async def close(self):
         logging.debug("Closing connection...")
         # close socket
+        if self.__receive_loop_task:
+            self.__receive_loop_task.cancel()
+        if self.__send_loop_task:
+            self.__send_loop_task.cancel()
         if self.__server:
             self.__server.cancel()
 

sdk/python/packages/flet/src/flet/cli/commands/run.py

@@ -1,14 +1,17 @@
 import argparse
 import os
+import signal
 import subprocess
 import sys
+import tempfile
 import threading
 import time
 from pathlib import Path
 
 from flet.cli.commands.base import BaseCommand
 from flet.flet import close_flet_view, open_flet_view
-from flet.utils import get_free_tcp_port, open_in_browser
+from flet.utils import get_free_tcp_port, is_windows, open_in_browser
+from flet_core.utils import random_string
 from watchdog.events import FileSystemEventHandler
 from watchdog.observers import Observer
 
@@ -82,9 +85,13 @@ def handle(self, options: argparse.Namespace) -> None:
         script_dir = os.path.dirname(script_path)
 
         port = options.port
-        if options.port is None:
+        if port is None and is_windows():
             port = get_free_tcp_port()
 
+        uds_path = None
+        if port is None and not is_windows():
+            uds_path = str(Path(tempfile.gettempdir()).joinpath(random_string(10)))
+
         assets_dir = options.assets_dir
         if assets_dir and not Path(assets_dir).is_absolute():
             assets_dir = str(
@@ -95,6 +102,7 @@ def handle(self, options: argparse.Namespace) -> None:
             [sys.executable, "-u", script_path],
             None if options.directory or options.recursive else script_path,
             port,
+            uds_path,
             options.web,
             options.hidden,
             assets_dir,
@@ -117,11 +125,14 @@ def handle(self, options: argparse.Namespace) -> None:
 
 
 class Handler(FileSystemEventHandler):
-    def __init__(self, args, script_path, port, web, hidden, assets_dir) -> None:
+    def __init__(
+        self, args, script_path, port, uds_path, web, hidden, assets_dir
+    ) -> None:
         super().__init__()
         self.args = args
         self.script_path = script_path
         self.port = port
+        self.uds_path = uds_path
         self.web = web
         self.hidden = hidden
         self.assets_dir = assets_dir
@@ -140,6 +151,8 @@ def start_process(self):
             p_env["FLET_FORCE_WEB_VIEW"] = "true"
         if self.port is not None:
             p_env["FLET_SERVER_PORT"] = str(self.port)
+        if self.uds_path is not None:
+            p_env["FLET_SERVER_UDS_PATH"] = self.uds_path
         p_env["FLET_DISPLAY_URL_PREFIX"] = self.page_url_prefix
 
         p_env["PYTHONIOENCODING"] = "utf-8"
@@ -187,12 +200,11 @@ def open_flet_view_and_wait(self):
             self.page_url, self.assets_dir, self.hidden
         )
         self.fvp.wait()
-        self.p.kill()
+        self.p.send_signal(signal.SIGTERM)
         self.terminate.set()
 
     def restart_program(self):
         self.is_running = False
-        self.p.kill()
+        self.p.send_signal(signal.SIGTERM)
         self.p.wait()
-        time.sleep(0.5)
         self.start_process()

sdk/python/packages/flet/src/flet/flet.py

@@ -205,7 +205,7 @@ async def app_async(
 
     def exit_gracefully(signum, frame):
         logging.debug("Gracefully terminating Flet app...")
-        terminate.set()
+        asyncio.get_running_loop().call_soon_threadsafe(terminate.set)
 
     signal.signal(signal.SIGINT, exit_gracefully)
     signal.signal(signal.SIGTERM, exit_gracefully)
@@ -270,6 +270,8 @@ def __connect_internal_sync(
     if env_port is not None and env_port:
         port = int(env_port)
 
+    uds_path = os.getenv("FLET_SERVER_UDS_PATH")
+
     is_desktop = view == FLET_APP or view == FLET_APP_HIDDEN
     if server is None and not is_desktop:
         server = __start_flet_server(
@@ -308,6 +310,7 @@ def on_session_created(conn, session_data):
     if is_desktop:
         conn = SyncLocalSocketConnection(
             port,
+            uds_path,
             on_event=on_event,
             on_session_created=on_session_created,
         )
@@ -342,6 +345,8 @@ async def __connect_internal_async(
     if env_port is not None and env_port:
         port = int(env_port)
 
+    uds_path = os.getenv("FLET_SERVER_UDS_PATH")
+
     is_desktop = view == FLET_APP or view == FLET_APP_HIDDEN
     if server is None and not is_desktop:
         server = __start_flet_server(
@@ -382,6 +387,7 @@ async def on_session_created(session_data):
     if is_desktop:
         conn = AsyncLocalSocketConnection(
             port,
+            uds_path,
             on_event=on_event,
             on_session_created=on_session_created,
         )

sdk/python/packages/flet/src/flet/sync_local_socket_connection.py

@@ -6,7 +6,7 @@
 import tempfile
 import threading
 from pathlib import Path
-from typing import List
+from typing import List, Optional
 
 from flet.utils import get_free_tcp_port, is_windows
 from flet_core.local_connection import LocalConnection
@@ -26,29 +26,32 @@ class SyncLocalSocketConnection(LocalConnection):
     def __init__(
         self,
         port: int = 0,
+        uds_path: Optional[str] = None,
         on_event=None,
         on_session_created=None,
     ):
         super().__init__()
         self.__port = port
+        self.__uds_path = uds_path
         self.__on_event = on_event
         self.__on_session_created = on_session_created
 
     def connect(self):
-        self.__uds_path = None
         if is_windows() or self.__port > 0:
             # TCP
             port = self.__port if self.__port > 0 else get_free_tcp_port()
             self.page_url = f"tcp://localhost:{port}"
             server_address = ("localhost", port)
             self.__sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.__sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
             logging.info(f"Starting up TCP server on {server_address}")
             self.__sock.bind(server_address)
         else:
             # UDS
-            self.__uds_path = str(
-                Path(tempfile.gettempdir()).joinpath(random_string(10))
-            )
+            if not self.__uds_path:
+                self.__uds_path = str(
+                    Path(tempfile.gettempdir()).joinpath(random_string(10))
+                )
             self.page_url = self.__uds_path
             self.__sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
             logging.info(f"Starting up UDS server on {self.__uds_path}")
@@ -173,7 +176,10 @@ def __recvall(self, sock, n):
         # Helper function to recv n bytes or return None if EOF is hit
         data = bytearray()
         while len(data) < n:
-            packet = sock.recv(n - len(data))
+            try:
+                packet = sock.recv(n - len(data))
+            except:
+                return None
             # print("packet received:", len(packet))
             if not packet:
                 return None