class SessionBase(asyncio.Protocol):
"""Base class of networking sessions.
There is no client / server distinction other than who initiated
the connection.
To initiate a connection to a remote server pass host, port and
proxy to the constructor, and then call create_connection(). Each
successful call should have a corresponding call to close().
Alternatively if used in a with statement, the connection is made
on entry to the block, and closed on exit from the block.
"""
max_errors = 10
def __init__(self, *, framer=None, loop=None):
self.framer = framer or self.default_framer()
self.loop = loop or asyncio.get_event_loop()
self.logger = logging.getLogger(self.__class__.__name__)
self.transport = None
# Set when a connection is made
self._address = None
self._proxy_address = None
# For logger.debug messages
self.verbosity = 0
# Cleared when the send socket is full
self._can_send = Event()
self._can_send.set()
self._pm_task = None
self._task_group = TaskGroup(self.loop)
# Force-close a connection if a send doesn't succeed in this time
self.max_send_delay = 60
# Statistics. The RPC object also keeps its own statistics.
self.start_time = time.perf_counter()
self.errors = 0
self.send_count = 0
self.send_size = 0
self.last_send = self.start_time
self.recv_count = 0
self.recv_size = 0
self.last_recv = self.start_time
self.last_packet_received = self.start_time
async def _limited_wait(self, secs):
try:
await asyncio.wait_for(self._can_send.wait(), secs)
except asyncio.TimeoutError:
self.abort()
raise asyncio.TimeoutError(f'task timed out after {secs}s')
async def _send_message(self, message):
if not self._can_send.is_set():
await self._limited_wait(self.max_send_delay)
if not self.is_closing():
framed_message = self.framer.frame(message)
self.send_size += len(framed_message)
self.send_count += 1
self.last_send = time.perf_counter()
if self.verbosity >= 4:
self.logger.debug(f'Sending framed message {framed_message}')
self.transport.write(framed_message)
def _bump_errors(self):
self.errors += 1
if self.errors >= self.max_errors:
# Don't await self.close() because that is self-cancelling
self._close()
def _close(self):
if self.transport:
self.transport.close()
# asyncio framework
def data_received(self, framed_message):
"""Called by asyncio when a message comes in."""
self.last_packet_received = time.perf_counter()
if self.verbosity >= 4:
self.logger.debug(f'Received framed message {framed_message}')
self.recv_size += len(framed_message)
self.framer.received_bytes(framed_message)
def pause_writing(self):
"""Transport calls when the send buffer is full."""
if not self.is_closing():
self._can_send.clear()
self.transport.pause_reading()
def resume_writing(self):
"""Transport calls when the send buffer has room."""
if not self._can_send.is_set():
self._can_send.set()
self.transport.resume_reading()
def connection_made(self, transport):
"""Called by asyncio when a connection is established.
Derived classes overriding this method must call this first."""
self.transport = transport
# This would throw if called on a closed SSL transport. Fixed
# in asyncio in Python 3.6.1 and 3.5.4
peer_address = transport.get_extra_info('peername')
# If the Socks proxy was used then _address is already set to
# the remote address
if self._address:
self._proxy_address = peer_address
else:
self._address = peer_address
self._pm_task = self.loop.create_task(self._receive_messages())
def connection_lost(self, exc):
"""Called by asyncio when the connection closes.
Tear down things done in connection_made."""
self._address = None
self.transport = None
self._task_group.cancel()
if self._pm_task:
self._pm_task.cancel()
# Release waiting tasks
self._can_send.set()
# External API
def default_framer(self):
"""Return a default framer."""
raise NotImplementedError
def peer_address(self):
"""Returns the peer's address (Python networking address), or None if
no connection or an error.
This is the result of socket.getpeername() when the connection
was made.
"""
return self._address
def peer_address_str(self):
"""Returns the peer's IP address and port as a human-readable
string."""
if not self._address:
return 'unknown'
ip_addr_str, port = self._address[:2]
if ':' in ip_addr_str:
return f'[{ip_addr_str}]:{port}'
else:
return f'{ip_addr_str}:{port}'
def is_closing(self):
"""Return True if the connection is closing."""
return not self.transport or self.transport.is_closing()
def abort(self):
"""Forcefully close the connection."""
if self.transport:
self.transport.abort()
# TODO: replace with synchronous_close
async def close(self, *, force_after=30):
"""Close the connection and return when closed."""
self._close()
if self._pm_task:
with suppress(CancelledError):
await asyncio.wait([self._pm_task], timeout=force_after)
self.abort()
await self._pm_task
def synchronous_close(self):
self._close()
if self._pm_task and not self._pm_task.done():
self._pm_task.cancel()
async def test_cancel_sets_it_done(self):
group = TaskGroup()
group.cancel()
self.assertTrue(group.done.is_set())