os-brick/os_brick/initiator/linuxsheepdog.py
yuyafei 14df0c7721 Remove unused LOG to keep code clean
TrivialFix

Change-Id: I2dde2430011a777bffc1f0d25886784c9ed04b68
2016-07-09 10:17:48 +08:00

115 lines
4.1 KiB
Python

# 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.
"""
Generic SheepDog Connection Utilities.
"""
import eventlet
import io
from oslo_concurrency import processutils
from os_brick import exception
from os_brick.i18n import _
class SheepdogVolumeIOWrapper(io.RawIOBase):
"""File-like object with Sheepdog backend."""
def __init__(self, addr, port, volume, snapshot_name=None):
self._addr = addr
self._port = port
self._vdiname = volume
self._snapshot_name = snapshot_name
self._offset = 0
# SheepdogVolumeIOWrapper instance becomes invalid
# if a write error occurs.
self._valid = True
def _execute(self, cmd, data=None):
try:
# NOTE(yamada-h): processutils.execute causes busy waiting
# under eventlet.
# To avoid wasting CPU resources, it should not be used for
# the command which takes long time to execute.
# For workaround, we replace a subprocess module with
# the original one while only executing a read/write command.
_processutils_subprocess = processutils.subprocess
processutils.subprocess = eventlet.patcher.original('subprocess')
return processutils.execute(*cmd, process_input=data)[0]
except (processutils.ProcessExecutionError, OSError):
self._valid = False
raise exception.VolumeDriverException(name=self._vdiname)
finally:
processutils.subprocess = _processutils_subprocess
def read(self, length=None):
if not self._valid:
raise exception.VolumeDriverException(name=self._vdiname)
cmd = ['dog', 'vdi', 'read', '-a', self._addr, '-p', self._port]
if self._snapshot_name:
cmd.extend(('-s', self._snapshot_name))
cmd.extend((self._vdiname, self._offset))
if length:
cmd.append(length)
data = self._execute(cmd)
self._offset += len(data)
return data
def write(self, data):
if not self._valid:
raise exception.VolumeDriverException(name=self._vdiname)
length = len(data)
cmd = ('dog', 'vdi', 'write', '-a', self._addr, '-p', self._port,
self._vdiname, self._offset, length)
self._execute(cmd, data)
self._offset += length
return length
def seek(self, offset, whence=0):
if not self._valid:
raise exception.VolumeDriverException(name=self._vdiname)
if whence == 0:
# SEEK_SET or 0 - start of the stream (the default);
# offset should be zero or positive
new_offset = offset
elif whence == 1:
# SEEK_CUR or 1 - current stream position; offset may be negative
new_offset = self._offset + offset
else:
# SEEK_END or 2 - end of the stream; offset is usually negative
# TODO(yamada-h): Support SEEK_END
raise IOError(_("Invalid argument - whence=%s not supported.") %
whence)
if new_offset < 0:
raise IOError(_("Invalid argument - negative seek offset."))
self._offset = new_offset
def tell(self):
return self._offset
def flush(self):
pass
def fileno(self):
"""Sheepdog does not have support for fileno so we raise IOError.
Raising IOError is recommended way to notify caller that interface is
not supported - see http://docs.python.org/2/library/io.html#io.IOBase
"""
raise IOError(_("fileno is not supported by SheepdogVolumeIOWrapper"))