Improve read_byte retry mechanism #8

comfospot40/parser.py

@@ -5,6 +5,7 @@
 import copy
 from datetime import datetime
 from serial import SerialException
+import asyncio
 
 
 class Parser:
@@ -19,12 +20,17 @@ def __init__(self, serial, packetlog=None, state=State()):
     def get_state(self):
         return self._state
 
-    async def read_byte(self):
+    async def read_byte(self, retries=5):
         while True:
             try:
                 return await self._ser.read(1)
             except SerialException as e:
-                logging.warn("Failed to read serial", e)
+                logging.warning("Failed to read serial: {}".format(e))
+                if retries > 0:
+                    await asyncio.sleep(0.1 * retries)
+                    retries -= 1
+                else:
+                    raise e
 
     async def search_length(self, data):
         logging.info("z")

tests/parser_test.py

@@ -0,0 +1,55 @@
+import asyncio
+import unittest
+import comfospot40
+import logging
+from serial import SerialException
+
+
+class TestStateLoad(unittest.IsolatedAsyncioTestCase):
+    async def test_read_byte_ok(self):
+        class TestSerial:
+            async def read(self, _):
+                return b"A"
+
+        s = TestSerial()
+        p = comfospot40.Parser(s)
+        self.assertEqual(b"A", await p.read_byte())
+
+    async def test_read_byte_error(self):
+        logging.disable(logging.CRITICAL)
+
+        class TestSerial:
+            async def read(self, _):
+                raise SerialException("something")
+                return b"A"
+
+        s = TestSerial()
+        p = comfospot40.Parser(s)
+        with self.assertRaises(SerialException):
+            await p.read_byte(0)
+
+    async def test_read_byte_retry(self):
+        logging.disable(logging.CRITICAL)
+
+        class TestSerial:
+            async def read(self, _):
+                raise SerialException("something")
+                return b"A"
+
+        s = TestSerial()
+        p = comfospot40.Parser(s)
+        with self.assertRaises(SerialException):
+            await asyncio.wait_for(p.read_byte(0), timeout=1)
+
+    async def test_read_byte_retry_timeout(self):
+        logging.disable(logging.CRITICAL)
+
+        class TestSerial:
+            async def read(self, _):
+                raise SerialException("something")
+                return b"A"
+
+        s = TestSerial()
+        p = comfospot40.Parser(s)
+        with self.assertRaises(asyncio.exceptions.TimeoutError):
+            await asyncio.wait_for(p.read_byte(2), timeout=0.1)