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cc280a129d
Since they were shared between write and read, and now the read is done constantly on a separate thread, the read lock would cause the write method to be locked and not functional at all
143 lines
5.1 KiB
Python
143 lines
5.1 KiB
Python
# Python rough implementation of a C# TCP client
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import socket
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import time
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from datetime import datetime, timedelta
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from io import BytesIO, BufferedWriter
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from threading import Event, Lock
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import errno
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from ..errors import ReadCancelledError
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class TcpClient:
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def __init__(self, proxy=None):
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self._proxy = proxy
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self._socket = None
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# Support for multi-threading advantages and safety
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self.cancelled = Event() # Has the read operation been cancelled?
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self.delay = 0.1 # Read delay when there was no data available
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self._lock = Lock()
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def _recreate_socket(self, mode):
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if self._proxy is None:
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self._socket = socket.socket(mode, socket.SOCK_STREAM)
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else:
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import socks
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self._socket = socks.socksocket(mode, socket.SOCK_STREAM)
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if type(self._proxy) is dict:
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self._socket.set_proxy(**self._proxy)
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else: # tuple, list, etc.
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self._socket.set_proxy(*self._proxy)
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def connect(self, ip, port, timeout):
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"""Connects to the specified IP and port number.
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'timeout' must be given in seconds
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"""
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if not self.connected:
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if ':' in ip: # IPv6
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self._recreate_socket(socket.AF_INET6)
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self._socket.settimeout(timeout)
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self._socket.connect((ip, port, 0, 0))
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else:
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self._recreate_socket(socket.AF_INET)
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self._socket.settimeout(timeout)
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self._socket.connect((ip, port))
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self._socket.setblocking(False)
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def _get_connected(self):
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return self._socket is not None
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connected = property(fget=_get_connected)
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def close(self):
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"""Closes the connection"""
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try:
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if self.connected:
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self._socket.shutdown(socket.SHUT_RDWR)
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self._socket.close()
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except OSError as e:
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if e.errno != errno.ENOTCONN:
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raise
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finally:
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self._socket = None
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def write(self, data):
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"""Writes (sends) the specified bytes to the connected peer"""
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# TODO Check whether the code using this has multiple threads calling
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# .write() on the very same socket. If so, have two locks, one for
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# .write() and another for .read().
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try:
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view = memoryview(data)
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total_sent, total = 0, len(data)
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while total_sent < total:
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try:
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sent = self._socket.send(view[total_sent:])
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if sent == 0:
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self.close()
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raise ConnectionResetError(
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'The server has closed the connection.')
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total_sent += sent
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except BlockingIOError:
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time.sleep(self.delay)
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except BrokenPipeError:
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self.close()
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raise
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def read(self, size, timeout=timedelta(seconds=5)):
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"""Reads (receives) a whole block of 'size bytes
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from the connected peer.
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A timeout can be specified, which will cancel the operation if
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no data has been read in the specified time. If data was read
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and it's waiting for more, the timeout will NOT cancel the
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operation. Set to None for no timeout
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"""
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# Ensure it is not cancelled at first, so we can enter the loop
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self.cancelled.clear()
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# Set the starting time so we can
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# calculate whether the timeout should fire
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start_time = datetime.now() if timeout is not None else None
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with BufferedWriter(BytesIO(), buffer_size=size) as buffer:
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bytes_left = size
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while bytes_left != 0:
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# Only do cancel if no data was read yet
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# Otherwise, carry on reading and finish
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if self.cancelled.is_set() and bytes_left == size:
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raise ReadCancelledError()
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try:
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partial = self._socket.recv(bytes_left)
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if len(partial) == 0:
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self.close()
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raise ConnectionResetError(
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'The server has closed the connection.')
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buffer.write(partial)
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bytes_left -= len(partial)
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except BlockingIOError as error:
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# No data available yet, sleep a bit
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time.sleep(self.delay)
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# Check if the timeout finished
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if timeout is not None:
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time_passed = datetime.now() - start_time
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if time_passed > timeout:
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raise TimeoutError(
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'The read operation exceeded the timeout.') from error
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# If everything went fine, return the read bytes
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buffer.flush()
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return buffer.raw.getvalue()
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def cancel_read(self):
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"""Cancels the read operation IF it hasn't yet
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started, raising a ReadCancelledError"""
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self.cancelled.set()
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