python/qemu: Change ConsoleSocket to optionally drain socket.

The primary purpose of this change is to clean up
machine.py's console_socket property to return a single type,
a ConsoleSocket.

ConsoleSocket now derives from a socket, which means that
in the default case (of not draining), machine.py
will see the same behavior as it did prior to ConsoleSocket.

Signed-off-by: Robert Foley <robert.foley@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200717203041.9867-3-robert.foley@linaro.org>
Message-Id: <20200724064509.331-16-alex.bennee@linaro.org>
This commit is contained in:
Robert Foley 2020-07-24 07:45:08 +01:00 committed by Alex Bennée
parent 4b84d87449
commit 80ded8e99d
2 changed files with 59 additions and 46 deletions

View File

@ -13,68 +13,75 @@ which can drain a socket and optionally dump the bytes to file.
# the COPYING file in the top-level directory.
#
import asyncore
import socket
import threading
from collections import deque
import time
class ConsoleSocket(asyncore.dispatcher):
class ConsoleSocket(socket.socket):
"""
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 (if drain==True), 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):
def __init__(self, address, file=None, drain=False):
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)
self._sock.connect(address)
socket.socket.__init__(self, socket.AF_UNIX, socket.SOCK_STREAM)
self.connect(address)
self._logfile = None
if file:
self._logfile = open(file, "w")
asyncore.dispatcher.__init__(self, sock=self._sock)
self._open = True
self._thread_start()
if drain:
self._drain_thread = self._thread_start()
else:
self._drain_thread = None
def _drain_fn(self):
"""Drains the socket and runs while the socket is open."""
while self._open:
try:
self._drain_socket()
except socket.timeout:
# The socket is expected to timeout since we set a
# short timeout to allow the thread to exit when
# self._open is set to False.
time.sleep(self._sleep_time)
def _thread_start(self):
"""Kick off a thread to wait on the asyncore.loop"""
if self._asyncore_thread is not None:
return
self._asyncore_thread = threading.Thread(target=asyncore.loop,
kwargs={'timeout':1})
self._asyncore_thread.daemon = True
self._asyncore_thread.start()
def handle_close(self):
"""redirect close to base class"""
# Call the base class close, but not self.close() since
# handle_close() occurs in the context of the thread which
# self.close() attempts to join.
asyncore.dispatcher.close(self)
"""Kick off a thread to drain the socket."""
# Configure socket to not block and timeout.
# This allows our drain thread to not block
# on recieve and exit smoothly.
socket.socket.setblocking(self, False)
socket.socket.settimeout(self, 1)
drain_thread = threading.Thread(target=self._drain_fn)
drain_thread.daemon = True
drain_thread.start()
return drain_thread
def close(self):
"""Close the base object and wait for the thread to terminate"""
if self._open:
self._open = False
asyncore.dispatcher.close(self)
if self._asyncore_thread is not None:
thread, self._asyncore_thread = self._asyncore_thread, None
if self._drain_thread is not None:
thread, self._drain_thread = self._drain_thread, None
thread.join()
socket.socket.close(self)
if self._logfile:
self._logfile.close()
self._logfile = None
def handle_read(self):
def _drain_socket(self):
"""process arriving characters into in memory _buffer"""
data = asyncore.dispatcher.recv(self, 1)
data = socket.socket.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.
@ -85,27 +92,38 @@ class ConsoleSocket(asyncore.dispatcher):
for c in string:
self._buffer.extend(c)
def recv(self, buffer_size=1):
def recv(self, bufsize=1):
"""Return chars from in memory buffer.
Maintains the same API as socket.socket.recv.
"""
if self._drain_thread is None:
# Not buffering the socket, pass thru to socket.
return socket.socket.recv(self, bufsize)
start_time = time.time()
while len(self._buffer) < buffer_size:
while len(self._buffer) < bufsize:
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(buffer_size)])
chars = ''.join([self._buffer.popleft() for i in range(bufsize)])
# 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
# socket w/o our intervention.
return chars.encode("latin1")
def set_blocking(self):
"""Maintain compatibility with socket API"""
pass
def setblocking(self, value):
"""When not draining we pass thru to the socket,
since when draining we control socket blocking.
"""
if self._drain_thread is None:
socket.socket.setblocking(self, value)
def settimeout(self, seconds):
"""Set current timeout on recv"""
self._recv_timeout_sec = seconds
"""When not draining we pass thru to the socket,
since when draining we control the timeout.
"""
if seconds is not None:
self._recv_timeout_sec = seconds
if self._drain_thread is None:
socket.socket.settimeout(self, seconds)

View File

@ -23,7 +23,6 @@ import os
import subprocess
import shutil
import signal
import socket
import tempfile
from typing import Optional, Type
from types import TracebackType
@ -673,12 +672,8 @@ class QEMUMachine:
Returns a socket connected to the console
"""
if self._console_socket is None:
if self._drain_console:
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)
self._console_socket.connect(self._console_address)
self._console_socket = console_socket.ConsoleSocket(
self._console_address,
file=self._console_log_path,
drain=self._drain_console)
return self._console_socket