A couple of serial port improvements

mu/logic.py

@@ -662,6 +662,7 @@ class DeviceList(QtCore.QAbstractListModel):
     def __init__(self, modes, parent=None):
         super().__init__(parent)
         self.modes = modes
+        self.force_check = False
         self._devices = list()
 
     def __iter__(self):
@@ -713,6 +714,7 @@ def add_device(self, new_device):
         # Insert
         self.beginInsertRows(parent, position, position)
         self._devices.insert(position, new_device)
+        self.force_check = True
         self.endInsertRows()
 
     def remove_device(self, device):
@@ -723,6 +725,7 @@ def remove_device(self, device):
         position = self._devices.index(device)
         self.beginRemoveRows(parent, position, position)
         self._devices.remove(device)
+        self.force_check = True
         self.endRemoveRows()
 
     def check_usb(self):
@@ -735,13 +738,21 @@ def check_usb(self):
         devices = []
         device_types = set()
         # Detect connected devices.
+        changed = False
         for mode_name, mode in self.modes.items():
+            if hasattr(mode, "check_devices"):
+                if not mode.check_devices():
+                    continue
             if hasattr(mode, "find_devices"):
                 # The mode can detect attached devices.
                 detected = mode.find_devices(with_logging=False)
+                changed = True
                 if detected:
                     device_types.add(mode_name)
                     devices.extend(detected)
+        if not changed and not self.force_check:
+            return
+
         # Remove no-longer connected devices.
         for device in self:
             if device not in devices:
@@ -776,6 +787,7 @@ def check_usb(self):
                         device.manufacturer,
                     )
                 )
+        self.force_check = False
 
 
 class Editor(QObject):

mu/modes/base.py

@@ -45,6 +45,38 @@
 MODULE_NAMES.add("builtins")
 
 
+class SerialPorts:
+    def __init__(self):
+        self.current_ports = []
+        self.current_sequence = 0
+        self.current_time = -1
+
+    def ports(self, force=False):
+        new_time = time.monotonic()
+        if force or new_time - self.current_time > 0.5:
+            self.current_time = new_time
+            available_ports = QSerialPortInfo.availablePorts()
+            if len(self.current_ports) != len(available_ports):
+                self.current_ports = available_ports
+                self.current_sequence += 1
+            else:
+                for i in range(len(available_ports)):
+                    old = self.current_ports[i]
+                    new = available_ports[i]
+                    if (
+                        old.portName() != new.portName()
+                        or old.description() != new.description()
+                        or old.serialNumber() != new.serialNumber()
+                    ):
+                        self.current_ports = available_ports
+                        self.current_sequence += 1
+                        break
+        return (self.current_ports, self.current_sequence)
+
+
+serial_ports = SerialPorts()
+
+
 class REPLConnection(QObject):
     serial = None
     data_received = pyqtSignal(bytes)
@@ -74,6 +106,13 @@ def baudrate(self):
         else:
             return None
 
+    @baudrate.setter
+    def baudrate(self, value):
+        if value != self._baudrate:
+            self._baudrate = value
+            if self.serial:
+                self.serial.setBaudRate(value)
+
     def open(self):
         """
         Open the serial link
@@ -379,6 +418,8 @@ class MicroPythonMode(BaseMode):
     connection = None
     baudrate = 115200
     builtins = ["const"]
+    current_devices = []
+    current_sequence = None
 
     def compatible_board(self, port):
         """
@@ -410,13 +451,24 @@ def compatible_board(self, port):
                 )
         return None
 
-    def find_devices(self, with_logging=True):
+    def check_devices(self):
+        """
+        Quickly check to see if the set of devices has
+        changed, return True if changed else False
+        """
+        (_, new_sequence) = serial_ports.ports()
+        return new_sequence != self.current_sequence
+
+    def find_devices(self, with_logging=True, force=False):
         """
         Returns the port and serial number, and name for the first
         MicroPython-ish device found connected to the host computer.
         If no device is found, returns the tuple (None, None, None).
         """
-        available_ports = QSerialPortInfo.availablePorts()
+        (available_ports, new_sequence) = serial_ports.ports(force)
+        if new_sequence == self.current_sequence:
+            return self.current_devices
+        self.current_sequence = new_sequence
         devices = []
         for port in available_ports:
             device = self.compatible_board(port)
@@ -448,6 +500,7 @@ def find_devices(self, with_logging=True):
                     for p in available_ports
                 ]
             )
+        self.current_devices = devices
         return devices
 
     def port_path(self, port_name):

mu/modes/snek.py

@@ -60,19 +60,18 @@ def set_ready(self):
             return
         self.ready = True
         if self.flowcontrol:
-            for self._baudrate in snek_bauds:
-                logger.info("Try baudrate %d" % self._baudrate)
-                self.serial.setBaudRate(self._baudrate)
-                self.serial.write(b"\x14\n")
+            for baudrate in snek_bauds:
+                logger.info("Try baudrate %d" % baudrate)
+                self.baudrate = baudrate
+                self.serial.write(b"\x14")
                 self.serial.waitForReadyRead(250)
                 if self.got_dc4:
                     logger.info("Autobaud response detected")
                     break
                 logger.info("No autobaud response")
             else:
-                self._baudrate = snek_bauds[0]
-                logger.info("Using default baudrate %d" % self._baudrate)
-                self.serial.setBaudRate(self._baudrate)
+                logger.info("Using default baudrate %d" % snek_bauds[0])
+                self.baudrate = snek_bauds[0]
         self.write(self.pending)
         self.pending = b""
 

tests/modes/test_base.py

@@ -287,7 +287,7 @@ def test_micropython_mode_find_device():
         ), mock.patch("mu.modes.base.os", mock_os), mock.patch(
             "mu.modes.base.sys", mock_sys
         ):
-            assert mm.find_devices() == [device]
+            assert mm.find_devices(force=True) == [device]
 
 
 def test_micropython_mode_find_device_no_ports():
@@ -300,7 +300,7 @@ def test_micropython_mode_find_device_no_ports():
     with mock.patch(
         "mu.modes.base.QSerialPortInfo.availablePorts", return_value=[]
     ):
-        assert mm.find_devices() == []
+        assert mm.find_devices(force=True) == []
 
 
 def test_micropython_mode_find_device_but_no_device():
@@ -318,7 +318,7 @@ def test_micropython_mode_find_device_but_no_device():
         "mu.modes.base.QSerialPortInfo.availablePorts",
         return_value=[mock_port],
     ):
-        assert mm.find_devices() == []
+        assert mm.find_devices(force=True) == []
 
 
 def test_micropython_mode_find_device_darwin_remove_extraneous_devices():
@@ -356,7 +356,7 @@ def test_micropython_mode_find_device_darwin_remove_extraneous_devices():
         "mu.modes.base.QSerialPortInfo.availablePorts",
         return_value=[mock_port, mock_port2],
     ):
-        assert mm.find_devices() == [device]
+        assert mm.find_devices(force=True) == [device]
 
 
 def test_micropython_mode_port_path_posix():