Changed slcan serial read routine to be faster and to manage the buffer more carefully (#2028)

* Changed slcan serial read routine to be faster and to manage the buffer more cauciously

* As per merge request suggestion

Co-authored-by: zariiii9003 <52598363+zariiii9003@users.noreply.github.com>

* as per merge request suggestion

Co-authored-by: zariiii9003 <52598363+zariiii9003@users.noreply.github.com>

* Simplified slcan serial reading

* Added news fragment

---------

Co-authored-by: Aaron Fulton <aaron@webtolife.software>
Co-authored-by: zariiii9003 <52598363+zariiii9003@users.noreply.github.com>

Author: 3 people

can/interfaces/slcan.py

@@ -218,17 +218,13 @@ def _read(self, timeout: float | None) -> str | None:
             while True:
                 # Due to accessing `serialPortOrig.in_waiting` too often will reduce the performance.
                 # We read the `serialPortOrig.in_waiting` only once here.
-                in_waiting = self.serialPortOrig.in_waiting
-                for _ in range(max(1, in_waiting)):
-                    new_byte = self.serialPortOrig.read(1)
-                    if new_byte:
-                        self._buffer.extend(new_byte)
-                    else:
-                        break
-
-                    if new_byte in (self._ERROR, self._OK):
-                        string = self._buffer.decode()
-                        self._buffer.clear()
+                size = self.serialPortOrig.in_waiting or 1
+                self._buffer.extend(self.serialPortOrig.read(size))
+
+                for i, byte in enumerate(self._buffer):
+                    if byte in (self._OK[0], self._ERROR[0]):
+                        string = self._buffer[: i + 1].decode()
+                        del self._buffer[: i + 1]
                         return string
 
                 if _timeout.expired():

doc/changelog.d/2028.changed.md

@@ -0,0 +1 @@
+Improved performance in slcan interface