Dashboard: use Popen() on Windows (#5110)

esphome/dashboard/dashboard.py

@@ -25,6 +25,7 @@ import tornado.ioloop
 import tornado.iostream
 import tornado.netutil
 import tornado.process
+import tornado.queues
 import tornado.web
 import tornado.websocket
 import yaml
@@ -202,7 +203,11 @@ class EsphomeCommandWebSocket(tornado.websocket.WebSocketHandler):
     def __init__(self, application, request, **kwargs):
         super().__init__(application, request, **kwargs)
         self._proc = None
+        self._queue = None
         self._is_closed = False
+        # Windows doesn't support non-blocking pipes,
+        # use Popen() with a reading thread instead
+        self._use_popen = os.name == "nt"
 
     @authenticated
     def on_message(self, message):
@@ -224,13 +229,28 @@ class EsphomeCommandWebSocket(tornado.websocket.WebSocketHandler):
             return
         command = self.build_command(json_message)
         _LOGGER.info("Running command '%s'", " ".join(shlex_quote(x) for x in command))
-        self._proc = tornado.process.Subprocess(
-            command,
-            stdout=tornado.process.Subprocess.STREAM,
-            stderr=subprocess.STDOUT,
-            stdin=tornado.process.Subprocess.STREAM,
-        )
-        self._proc.set_exit_callback(self._proc_on_exit)
+
+        if self._use_popen:
+            self._queue = tornado.queues.Queue()
+            # pylint: disable=consider-using-with
+            self._proc = subprocess.Popen(
+                command,
+                stdin=subprocess.PIPE,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT,
+            )
+            stdout_thread = threading.Thread(target=self._stdout_thread)
+            stdout_thread.daemon = True
+            stdout_thread.start()
+        else:
+            self._proc = tornado.process.Subprocess(
+                command,
+                stdout=tornado.process.Subprocess.STREAM,
+                stderr=subprocess.STDOUT,
+                stdin=tornado.process.Subprocess.STREAM,
+            )
+            self._proc.set_exit_callback(self._proc_on_exit)
+
         tornado.ioloop.IOLoop.current().spawn_callback(self._redirect_stdout)
 
     @property
@@ -252,7 +272,13 @@ class EsphomeCommandWebSocket(tornado.websocket.WebSocketHandler):
 
         while True:
             try:
-                data = yield self._proc.stdout.read_until_regex(reg)
+                if self._use_popen:
+                    data = yield self._queue.get()
+                    if data is None:
+                        self._proc_on_exit(self._proc.poll())
+                        break
+                else:
+                    data = yield self._proc.stdout.read_until_regex(reg)
             except tornado.iostream.StreamClosedError:
                 break
             data = codecs.decode(data, "utf8", "replace")
@@ -260,6 +286,19 @@ class EsphomeCommandWebSocket(tornado.websocket.WebSocketHandler):
             _LOGGER.debug("> stdout: %s", data)
             self.write_message({"event": "line", "data": data})
 
+    def _stdout_thread(self):
+        if not self._use_popen:
+            return
+        while True:
+            data = self._proc.stdout.readline()
+            if data:
+                data = data.replace(b"\r", b"")
+                self._queue.put_nowait(data)
+            if self._proc.poll() is not None:
+                break
+        self._proc.wait(1.0)
+        self._queue.put_nowait(None)
+
     def _proc_on_exit(self, returncode):
         if not self._is_closed:
             # Check if the proc was not forcibly closed
@@ -270,7 +309,10 @@ class EsphomeCommandWebSocket(tornado.websocket.WebSocketHandler):
         # Check if proc exists (if 'start' has been run)
         if self.is_process_active:
             _LOGGER.debug("Terminating process")
-            self._proc.proc.terminate()
+            if self._use_popen:
+                self._proc.terminate()
+            else:
+                self._proc.proc.terminate()
         # Shutdown proc on WS close
         self._is_closed = True