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python/aqmp: add logging to AsyncProtocol

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Give the connection and the reader/writer tasks nicknames, and add
logging statements throughout.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
John Snow 2021-09-15 12:29:36 -04:00
parent c1408345af
commit 50e533061f
1 changed files with 73 additions and 9 deletions
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82
python/qemu/aqmp/protocol.py
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@ -14,6 +14,7 @@ import asyncio
from asyncio import StreamReader, StreamWriter
from enum import Enum
from functools import wraps
import logging
from ssl import SSLContext
from typing import (
Any,
@ -32,8 +33,10 @@ from .error import AQMPError
from .util import (
bottom_half,
create_task,
exception_summary,
flush,
is_closing,
pretty_traceback,
upper_half,
wait_closed,
)
@ -174,14 +177,28 @@ class AsyncProtocol(Generic[T]):
can be written after the super() call.
- `_on_message`:
Actions to be performed when a message is received.
:param name:
Name used for logging messages, if any. By default, messages
will log to 'qemu.aqmp.protocol', but each individual connection
can be given its own logger by giving it a name; messages will
then log to 'qemu.aqmp.protocol.${name}'.
"""
# pylint: disable=too-many-instance-attributes
#: Logger object for debugging messages from this connection.
logger = logging.getLogger(__name__)
# -------------------------
# Section: Public interface
# -------------------------
def __init__(self) -> None:
def __init__(self, name: Optional[str] = None) -> None:
#: The nickname for this connection, if any.
self.name: Optional[str] = name
if self.name is not None:
self.logger = self.logger.getChild(self.name)
# stream I/O
self._reader: Optional[StreamReader] = None
self._writer: Optional[StreamWriter] = None
@ -205,6 +222,14 @@ class AsyncProtocol(Generic[T]):
self._runstate = Runstate.IDLE
self._runstate_changed: Optional[asyncio.Event] = None
def __repr__(self) -> str:
cls_name = type(self).__name__
tokens = []
if self.name is not None:
tokens.append(f"name={self.name!r}")
tokens.append(f"runstate={self.runstate.name}")
return f"<{cls_name} {' '.join(tokens)}>"
@property # @upper_half
def runstate(self) -> Runstate:
"""The current `Runstate` of the connection."""
@ -246,6 +271,7 @@ class AsyncProtocol(Generic[T]):
:raise Exception: When the reader or writer terminate unexpectedly.
"""
self.logger.debug("disconnect() called.")
self._schedule_disconnect()
await self._wait_disconnect()
@ -273,6 +299,8 @@ class AsyncProtocol(Generic[T]):
if state == self._runstate:
return
self.logger.debug("Transitioning from '%s' to '%s'.",
str(self._runstate), str(state))
self._runstate = state
self._runstate_event.set()
self._runstate_event.clear()
@ -312,8 +340,15 @@ class AsyncProtocol(Generic[T]):
except BaseException as err:
emsg = f"Failed to establish {phase}"
# Reset from CONNECTING back to IDLE.
await self.disconnect()
self.logger.error("%s: %s", emsg, exception_summary(err))
self.logger.debug("%s:\n%s\n", emsg, pretty_traceback())
try:
# Reset from CONNECTING back to IDLE.
await self.disconnect()
except:
emsg = "Unexpected bottom half exception"
self.logger.critical("%s:\n%s\n", emsg, pretty_traceback())
raise
# NB: CancelledError is not a BaseException before Python 3.8
if isinstance(err, asyncio.CancelledError):
@ -363,12 +398,16 @@ class AsyncProtocol(Generic[T]):
:raise OSError: For stream-related errors.
"""
self.logger.debug("Connecting to %s ...", address)
if isinstance(address, tuple):
connect = asyncio.open_connection(address[0], address[1], ssl=ssl)
else:
connect = asyncio.open_unix_connection(path=address, ssl=ssl)
self._reader, self._writer = await connect
self.logger.debug("Connected.")
@upper_half
async def _establish_session(self) -> None:
"""
@ -382,8 +421,8 @@ class AsyncProtocol(Generic[T]):
self._outgoing = asyncio.Queue()
reader_coro = self._bh_loop_forever(self._bh_recv_message)
writer_coro = self._bh_loop_forever(self._bh_send_message)
reader_coro = self._bh_loop_forever(self._bh_recv_message, 'Reader')
writer_coro = self._bh_loop_forever(self._bh_send_message, 'Writer')
self._reader_task = create_task(reader_coro)
self._writer_task = create_task(writer_coro)
@ -410,6 +449,7 @@ class AsyncProtocol(Generic[T]):
"""
if not self._dc_task:
self._set_state(Runstate.DISCONNECTING)
self.logger.debug("Scheduling disconnect.")
self._dc_task = create_task(self._bh_disconnect())
@upper_half
@ -492,30 +532,39 @@ class AsyncProtocol(Generic[T]):
# Try to flush the writer, if possible:
if not error_pathway:
await self._bh_flush_writer()
except:
except BaseException as err:
error_pathway = True
emsg = "Failed to flush the writer"
self.logger.error("%s: %s", emsg, exception_summary(err))
self.logger.debug("%s:\n%s\n", emsg, pretty_traceback())
raise
finally:
# Cancel any still-running tasks:
if self._writer_task is not None and not self._writer_task.done():
self.logger.debug("Cancelling writer task.")
self._writer_task.cancel()
if self._reader_task is not None and not self._reader_task.done():
self.logger.debug("Cancelling reader task.")
self._reader_task.cancel()
# Close out the tasks entirely (Won't raise):
if tasks:
self.logger.debug("Waiting for tasks to complete ...")
await asyncio.wait(tasks)
# Lastly, close the stream itself. (May raise):
await self._bh_close_stream(error_pathway)
self.logger.debug("Disconnected.")
@bottom_half
async def _bh_flush_writer(self) -> None:
if not self._writer_task:
return
self.logger.debug("Draining the outbound queue ...")
await self._outgoing.join()
if self._writer is not None:
self.logger.debug("Flushing the StreamWriter ...")
await flush(self._writer)
@bottom_half
@ -525,8 +574,10 @@ class AsyncProtocol(Generic[T]):
return
if not is_closing(self._writer):
self.logger.debug("Closing StreamWriter.")
self._writer.close()
self.logger.debug("Waiting for StreamWriter to close ...")
try:
await wait_closed(self._writer)
except Exception: # pylint: disable=broad-except
@ -541,13 +592,18 @@ class AsyncProtocol(Generic[T]):
# just trust that the Exception we already have is the
# better one to present to the user, even if we don't
# genuinely *know* the relationship between the two.
pass
self.logger.debug(
"Discarding Exception from wait_closed:\n%s\n",
pretty_traceback(),
)
else:
# Oops, this is a brand-new error!
raise
finally:
self.logger.debug("StreamWriter closed.")
@bottom_half
async def _bh_loop_forever(self, async_fn: _TaskFN) -> None:
async def _bh_loop_forever(self, async_fn: _TaskFN, name: str) -> None:
"""
Run one of the bottom-half methods in a loop forever.
@ -555,16 +611,24 @@ class AsyncProtocol(Generic[T]):
disconnect that will terminate the entire loop.
:param async_fn: The bottom-half method to run in a loop.
:param name: The name of this task, used for logging.
"""
try:
while True:
await async_fn()
except asyncio.CancelledError:
# We have been cancelled by _bh_disconnect, exit gracefully.
self.logger.debug("Task.%s: cancelled.", name)
return
except BaseException:
except BaseException as err:
self.logger.error("Task.%s: %s",
name, exception_summary(err))
self.logger.debug("Task.%s: failure:\n%s\n",
name, pretty_traceback())
self._schedule_disconnect()
raise
finally:
self.logger.debug("Task.%s: exiting.", name)
@bottom_half
async def _bh_send_message(self) -> None: