python/qemu: Cleanup changes to ConsoleSocket

The changes to console_socket.py and machine.py are to
cleanup for pylint and flake8.

Signed-off-by: Robert Foley <robert.foley@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20200717203041.9867-2-robert.foley@linaro.org>
Message-Id: <20200724064509.331-15-alex.bennee@linaro.org>

python/qemu/console_socket.py

-#!/usr/bin/env python3
-#
-# This python module implements a ConsoleSocket object which is
-# designed always drain the socket itself, and place
-# the bytes into a in memory buffer for later processing.
-#
-# Optionally a file path can be passed in and we will also
-# dump the characters to this file for debug.
-#
+"""
+QEMU Console Socket Module:
+
+This python module implements a ConsoleSocket object,
+which can drain a socket and optionally dump the bytes to file.
+"""
 # Copyright 2020 Linaro
 #
 # Authors:
@@ -15,20 +12,27 @@
 # This code is licensed under the GPL version 2 or later.  See
 # the COPYING file in the top-level directory.
 #
+
 import asyncore
 import socket
 import threading
-import io
-import os
-import sys
 from collections import deque
 import time
-import traceback
+
 
 class ConsoleSocket(asyncore.dispatcher):
+    """
+    ConsoleSocket represents a socket attached to a char device.
 
+    Drains the socket and places the bytes into an in memory buffer
+    for later processing.
+
+    Optionally a file path can be passed in and we will also
+    dump the characters to this file for debugging purposes.
+    """
     def __init__(self, address, file=None):
         self._recv_timeout_sec = 300
+        self._sleep_time = 0.5
         self._buffer = deque()
         self._asyncore_thread = None
         self._sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
@@ -70,31 +74,28 @@ def close(self):
 
     def handle_read(self):
         """process arriving characters into in memory _buffer"""
-        try:
-            data = asyncore.dispatcher.recv(self, 1)
-            # latin1 is needed since there are some chars
-            # we are receiving that cannot be encoded to utf-8
-            # such as 0xe2, 0x80, 0xA6.
-            string = data.decode("latin1")
-        except:
-            print("Exception seen.")
-            traceback.print_exc()
-            return
+        data = asyncore.dispatcher.recv(self, 1)
+        # latin1 is needed since there are some chars
+        # we are receiving that cannot be encoded to utf-8
+        # such as 0xe2, 0x80, 0xA6.
+        string = data.decode("latin1")
         if self._logfile:
             self._logfile.write("{}".format(string))
             self._logfile.flush()
         for c in string:
             self._buffer.extend(c)
 
-    def recv(self, n=1, sleep_delay_s=0.1):
-        """Return chars from in memory buffer"""
+    def recv(self, buffer_size=1):
+        """Return chars from in memory buffer.
+           Maintains the same API as socket.socket.recv.
+        """
         start_time = time.time()
-        while len(self._buffer) < n:
-            time.sleep(sleep_delay_s)
+        while len(self._buffer) < buffer_size:
+            time.sleep(self._sleep_time)
             elapsed_sec = time.time() - start_time
             if elapsed_sec > self._recv_timeout_sec:
                 raise socket.timeout
-        chars = ''.join([self._buffer.popleft() for i in range(n)])
+        chars = ''.join([self._buffer.popleft() for i in range(buffer_size)])
         # We choose to use latin1 to remain consistent with
         # handle_read() and give back the same data as the user would
         # receive if they were reading directly from the

python/qemu/machine.py

@@ -27,7 +27,7 @@
 import tempfile
 from typing import Optional, Type
 from types import TracebackType
-from qemu.console_socket import ConsoleSocket
+from . import console_socket
 
 from . import qmp
 
@@ -674,8 +674,9 @@ def console_socket(self):
         """
         if self._console_socket is None:
             if self._drain_console:
-                self._console_socket = ConsoleSocket(self._console_address,
-                                                    file=self._console_log_path)
+                self._console_socket = console_socket.ConsoleSocket(
+                    self._console_address,
+                    file=self._console_log_path)
             else:
                 self._console_socket = socket.socket(socket.AF_UNIX,
                                                      socket.SOCK_STREAM)

python/qemu/pylintrc

@@ -33,7 +33,7 @@ good-names=i,
            Run,
            _,
            fd,
-
+           c,
 [VARIABLES]
 
 [STRING]