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"""File-system Transport.
Transport using the file-system as the message store.
"""
import os
import shutil
import uuid
from queue import Empty
import tempfile
from time import monotonic
from . import virtual
from kombu.exceptions import ChannelError
from kombu.utils.encoding import bytes_to_str, str_to_bytes
from kombu.utils.json import loads, dumps
from kombu.utils.objects import cached_property
VERSION = (1, 0, 0)
__version__ = '.'.join(map(str, VERSION))
# needs win32all to work on Windows
if os.name == 'nt':
import win32con
import win32file
import pywintypes
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
# 0 is the default
LOCK_SH = 0 # noqa
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY # noqa
__overlapped = pywintypes.OVERLAPPED()
def lock(file, flags):
"""Create file lock."""
hfile = win32file._get_osfhandle(file.fileno())
win32file.LockFileEx(hfile, flags, 0, 0xffff0000, __overlapped)
def unlock(file):
"""Remove file lock."""
hfile = win32file._get_osfhandle(file.fileno())
win32file.UnlockFileEx(hfile, 0, 0xffff0000, __overlapped)
elif os.name == 'posix':
import fcntl
from fcntl import LOCK_EX, LOCK_SH, LOCK_NB # noqa
def lock(file, flags): # noqa
"""Create file lock."""
fcntl.flock(file.fileno(), flags)
def unlock(file): # noqa
"""Remove file lock."""
fcntl.flock(file.fileno(), fcntl.LOCK_UN)
else:
raise RuntimeError(
'Filesystem plugin only defined for NT and POSIX platforms')
class Channel(virtual.Channel):
"""Filesystem Channel."""
def _put(self, queue, payload, **kwargs):
"""Put `message` onto `queue`."""
filename = '{}_{}.{}.msg'.format(int(round(monotonic() * 1000)),
uuid.uuid4(), queue)
filename = os.path.join(self.data_folder_out, filename)
try:
f = open(filename, 'wb')
lock(f, LOCK_EX)
f.write(str_to_bytes(dumps(payload)))
except OSError:
raise ChannelError(
f'Cannot add file {filename!r} to directory')
finally:
unlock(f)
f.close()
def _get(self, queue):
"""Get next message from `queue`."""
queue_find = '.' + queue + '.msg'
folder = os.listdir(self.data_folder_in)
folder = sorted(folder)
while len(folder) > 0:
filename = folder.pop(0)
# only handle message for the requested queue
if filename.find(queue_find) < 0:
continue
if self.store_processed:
processed_folder = self.processed_folder
else:
processed_folder = tempfile.gettempdir()
try:
# move the file to the tmp/processed folder
shutil.move(os.path.join(self.data_folder_in, filename),
processed_folder)
except OSError:
pass # file could be locked, or removed in meantime so ignore
filename = os.path.join(processed_folder, filename)
try:
f = open(filename, 'rb')
payload = f.read()
f.close()
if not self.store_processed:
os.remove(filename)
except OSError:
raise ChannelError(
f'Cannot read file {filename!r} from queue.')
return loads(bytes_to_str(payload))
raise Empty()
def _purge(self, queue):
"""Remove all messages from `queue`."""
count = 0
queue_find = '.' + queue + '.msg'
folder = os.listdir(self.data_folder_in)
while len(folder) > 0:
filename = folder.pop()
try:
# only purge messages for the requested queue
if filename.find(queue_find) < 0:
continue
filename = os.path.join(self.data_folder_in, filename)
os.remove(filename)
count += 1
except OSError:
# we simply ignore its existence, as it was probably
# processed by another worker
pass
return count
def _size(self, queue):
"""Return the number of messages in `queue` as an :class:`int`."""
count = 0
queue_find = f'.{queue}.msg'
folder = os.listdir(self.data_folder_in)
while len(folder) > 0:
filename = folder.pop()
# only handle message for the requested queue
if filename.find(queue_find) < 0:
continue
count += 1
return count
@property
def transport_options(self):
return self.connection.client.transport_options
@cached_property
def data_folder_in(self):
return self.transport_options.get('data_folder_in', 'data_in')
@cached_property
def data_folder_out(self):
return self.transport_options.get('data_folder_out', 'data_out')
@cached_property
def store_processed(self):
return self.transport_options.get('store_processed', False)
@cached_property
def processed_folder(self):
return self.transport_options.get('processed_folder', 'processed')
class Transport(virtual.Transport):
"""Filesystem Transport."""
Channel = Channel
default_port = 0
driver_type = 'filesystem'
driver_name = 'filesystem'
def driver_version(self):
return 'N/A'
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