/usr/lib/python2.7/dist-packages/os_win/utils/io/namedpipe.py is in python-os-win 0.4.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import errno
import os
from eventlet import patcher
from oslo_log import log as logging
from os_win._i18n import _
from os_win import constants
from os_win import exceptions
from os_win.utils.io import ioutils
threading = patcher.original('threading')
time = patcher.original('time')
LOG = logging.getLogger(__name__)
class NamedPipeHandler(object):
"""Handles asyncronous I/O operations on a specified named pipe."""
_MAX_LOG_ROTATE_RETRIES = 5
def __init__(self, pipe_name, input_queue=None, output_queue=None,
connect_event=None, log_file=None):
self._pipe_name = pipe_name
self._input_queue = input_queue
self._output_queue = output_queue
self._log_file_path = log_file
self._connect_event = connect_event
self._stopped = threading.Event()
self._workers = []
self._pipe_handle = None
self._lock = threading.Lock()
self._ioutils = ioutils.IOUtils()
self._setup_io_structures()
def start(self):
try:
self._open_pipe()
if self._log_file_path:
self._log_file_handle = open(self._log_file_path, 'ab', 1)
jobs = [self._read_from_pipe]
if self._input_queue and self._connect_event:
jobs.append(self._write_to_pipe)
for job in jobs:
worker = threading.Thread(target=job)
worker.setDaemon(True)
worker.start()
self._workers.append(worker)
except Exception as err:
msg = (_("Named pipe handler failed to initialize. "
"Pipe Name: %(pipe_name)s "
"Error: %(err)s") %
{'pipe_name': self._pipe_name,
'err': err})
LOG.error(msg)
self.stop()
raise exceptions.OSWinException(msg)
def stop(self):
self._stopped.set()
# If any worker has been spawned already, we rely on it to have
# cleaned up the handles before ending its execution.
# Note that we expect the caller to synchronize the start/stop calls.
if not self._workers:
self._cleanup_handles()
for worker in self._workers:
# It may happen that another IO request was issued right after
# we've set the stopped event and canceled pending requests.
# In this case, retrying will ensure that the IO workers are
# stopped properly and that there are no more outstanding IO
# operations.
while (worker.is_alive() and
worker is not threading.current_thread()):
self._cancel_io()
worker.join(0.5)
self._workers = []
def _cleanup_handles(self):
self._close_pipe()
if self._log_file_handle:
self._log_file_handle.close()
self._log_file_handle = None
def _setup_io_structures(self):
self._r_buffer = self._ioutils.get_buffer(
constants.SERIAL_CONSOLE_BUFFER_SIZE)
self._w_buffer = self._ioutils.get_buffer(
constants.SERIAL_CONSOLE_BUFFER_SIZE)
self._r_overlapped = self._ioutils.get_new_overlapped_structure()
self._w_overlapped = self._ioutils.get_new_overlapped_structure()
self._r_completion_routine = self._ioutils.get_completion_routine(
self._read_callback)
self._w_completion_routine = self._ioutils.get_completion_routine()
self._log_file_handle = None
def _open_pipe(self):
"""Opens a named pipe in overlapped mode for asyncronous I/O."""
self._ioutils.wait_named_pipe(self._pipe_name)
self._pipe_handle = self._ioutils.open(
self._pipe_name,
desired_access=(ioutils.GENERIC_READ | ioutils.GENERIC_WRITE),
share_mode=(ioutils.FILE_SHARE_READ | ioutils.FILE_SHARE_WRITE),
creation_disposition=ioutils.OPEN_EXISTING,
flags_and_attributes=ioutils.FILE_FLAG_OVERLAPPED)
def _close_pipe(self):
if self._pipe_handle:
self._ioutils.close_handle(self._pipe_handle)
self._pipe_handle = None
def _cancel_io(self):
if self._pipe_handle:
# We ignore invalid handle errors. Even if the pipe is closed
# and the handle reused, by specifing the overlapped structures
# we ensure that we don't cancel IO operations other than the
# ones that we care about.
self._ioutils.cancel_io(self._pipe_handle, self._r_overlapped,
ignore_invalid_handle=True)
self._ioutils.cancel_io(self._pipe_handle, self._w_overlapped,
ignore_invalid_handle=True)
def _read_from_pipe(self):
self._start_io_worker(self._ioutils.read,
self._r_buffer,
self._r_overlapped,
self._r_completion_routine)
def _write_to_pipe(self):
self._start_io_worker(self._ioutils.write,
self._w_buffer,
self._w_overlapped,
self._w_completion_routine,
self._get_data_to_write)
def _start_io_worker(self, func, buff, overlapped_structure,
completion_routine, buff_update_func=None):
try:
while not self._stopped.isSet():
if buff_update_func:
num_bytes = buff_update_func()
if not num_bytes:
continue
else:
num_bytes = len(buff)
func(self._pipe_handle, buff, num_bytes,
overlapped_structure, completion_routine)
except Exception:
self._stopped.set()
finally:
with self._lock:
self._cleanup_handles()
def _read_callback(self, num_bytes):
data = self._ioutils.get_buffer_data(self._r_buffer,
num_bytes)
if self._output_queue:
self._output_queue.put(data)
if self._log_file_handle:
self._write_to_log(data)
def _get_data_to_write(self):
while not (self._stopped.isSet() or self._connect_event.isSet()):
time.sleep(1)
data = self._input_queue.get()
if data:
self._ioutils.write_buffer_data(self._w_buffer, data)
return len(data)
return 0
def _write_to_log(self, data):
if self._stopped.isSet():
return
try:
log_size = self._log_file_handle.tell() + len(data)
if log_size >= constants.MAX_CONSOLE_LOG_FILE_SIZE:
self._rotate_logs()
self._log_file_handle.write(data)
except Exception:
self._stopped.set()
def _rotate_logs(self):
self._log_file_handle.flush()
self._log_file_handle.close()
log_archive_path = self._log_file_path + '.1'
if os.path.exists(log_archive_path):
self._retry_if_file_in_use(os.remove,
log_archive_path)
self._retry_if_file_in_use(os.rename,
self._log_file_path,
log_archive_path)
self._log_file_handle = open(
self._log_file_path, 'ab', 1)
def _retry_if_file_in_use(self, f, *args, **kwargs):
# The log files might be in use if the console log is requested
# while a log rotation is attempted.
retry_count = 0
while True:
try:
return f(*args, **kwargs)
except WindowsError as err:
if (err.errno == errno.EACCES and
retry_count < self._MAX_LOG_ROTATE_RETRIES):
retry_count += 1
time.sleep(1)
else:
raise
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