# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb. If not, see <http://www.gnu.org/licenses/>.
"""custom storages for the system source"""
from os import unlink, path as osp
from yams.schema import role_name
from cubicweb import Binary, ValidationError
from cubicweb.server import hook
def set_attribute_storage(repo, etype, attr, storage):
repo.system_source.set_storage(etype, attr, storage)
def unset_attribute_storage(repo, etype, attr):
repo.system_source.unset_storage(etype, attr)
class Storage(object):
"""abstract storage
* If `source_callback` is true (by default), the callback will be run during
query result process of fetched attribute's value and should have the
following prototype::
callback(self, source, session, value)
where `value` is the value actually stored in the backend. None values
will be skipped (eg callback won't be called).
* if `source_callback` is false, the callback will be run during sql
generation when some attribute with a custom storage is accessed and
should have the following prototype::
callback(self, generator, relation, linkedvar)
where `generator` is the sql generator, `relation` the current rql syntax
tree relation and linkedvar the principal syntax tree variable holding the
attribute.
"""
is_source_callback = True
def callback(self, *args):
"""see docstring for prototype, which vary according to is_source_callback
"""
raise NotImplementedError()
def entity_added(self, entity, attr):
"""an entity using this storage for attr has been added"""
raise NotImplementedError()
def entity_updated(self, entity, attr):
"""an entity using this storage for attr has been updatded"""
raise NotImplementedError()
def entity_deleted(self, entity, attr):
"""an entity using this storage for attr has been deleted"""
raise NotImplementedError()
def migrate_entity(self, entity, attribute):
"""migrate an entity attribute to the storage"""
raise NotImplementedError()
# TODO
# * make it configurable without code
# * better file path attribution
# * handle backup/restore
def uniquify_path(dirpath, basename):
"""return a unique file name for `basename` in `dirpath`, or None
if all attemps failed.
XXX subject to race condition.
"""
path = osp.join(dirpath, basename.replace(osp.sep, '-'))
if not osp.isfile(path):
return path
base, ext = osp.splitext(path)
for i in xrange(1, 256):
path = '%s%s%s' % (base, i, ext)
if not osp.isfile(path):
return path
return None
class BytesFileSystemStorage(Storage):
"""store Bytes attribute value on the file system"""
def __init__(self, defaultdir, fsencoding='utf-8'):
self.default_directory = defaultdir
self.fsencoding = fsencoding
def callback(self, source, session, value):
"""sql generator callback when some attribute with a custom storage is
accessed
"""
fpath = source.binary_to_str(value)
try:
return Binary(file(fpath, 'rb').read())
except OSError, ex:
source.critical("can't open %s: %s", value, ex)
return None
def entity_added(self, entity, attr):
"""an entity using this storage for attr has been added"""
if entity._cw.transaction_data.get('fs_importing'):
binary = Binary(file(entity[attr].getvalue(), 'rb').read())
else:
binary = entity.pop(attr)
fpath = self.new_fs_path(entity, attr)
# bytes storage used to store file's path
entity[attr] = Binary(fpath)
file(fpath, 'wb').write(binary.getvalue())
hook.set_operation(entity._cw, 'bfss_added', fpath, AddFileOp)
return binary
def entity_updated(self, entity, attr):
"""an entity using this storage for attr has been updatded"""
# get the name of the previous file containing the value
oldpath = self.current_fs_path(entity, attr)
if entity._cw.transaction_data.get('fs_importing'):
# If we are importing from the filesystem, the file already exists.
# We do not need to create it but we need to fetch the content of
# the file as the actual content of the attribute
fpath = entity[attr].getvalue()
binary = Binary(file(fpath, 'rb').read())
else:
# We must store the content of the attributes
# into a file to stay consistent with the behaviour of entity_add.
# Moreover, the BytesFileSystemStorage expects to be able to
# retrieve the current value of the attribute at anytime by reading
# the file on disk. To be able to rollback things, use a new file
# and keep the old one that will be removed on commit if everything
# went ok.
#
# fetch the current attribute value in memory
binary = entity.pop(attr)
# Get filename for it
fpath = self.new_fs_path(entity, attr)
assert not osp.exists(fpath)
# write attribute value on disk
file(fpath, 'wb').write(binary.getvalue())
# Mark the new file as added during the transaction.
# The file will be removed on rollback
hook.set_operation(entity._cw, 'bfss_added', fpath, AddFileOp)
if oldpath != fpath:
# register the new location for the file.
entity[attr] = Binary(fpath)
# Mark the old file as useless so the file will be removed at
# commit.
hook.set_operation(entity._cw, 'bfss_deleted', oldpath,
DeleteFileOp)
return binary
def entity_deleted(self, entity, attr):
"""an entity using this storage for attr has been deleted"""
fpath = self.current_fs_path(entity, attr)
hook.set_operation(entity._cw, 'bfss_deleted', fpath, DeleteFileOp)
def new_fs_path(self, entity, attr):
# We try to get some hint about how to name the file using attribute's
# name metadata, so we use the real file name and extension when
# available. Keeping the extension is useful for example in the case of
# PIL processing that use filename extension to detect content-type, as
# well as providing more understandable file names on the fs.
basename = [str(entity.eid), attr]
name = entity.cw_attr_metadata(attr, 'name')
if name is not None:
basename.append(name.encode(self.fsencoding))
fspath = uniquify_path(self.default_directory, '_'.join(basename))
if fspath is None:
msg = entity._cw._('failed to uniquify path (%s, %s)') % (
self.default_directory, '_'.join(basename))
raise ValidationError(entity.eid, {role_name(attr, 'subject'): msg})
return fspath
def current_fs_path(self, entity, attr):
sysource = entity._cw.pool.source('system')
cu = sysource.doexec(entity._cw,
'SELECT cw_%s FROM cw_%s WHERE cw_eid=%s' % (
attr, entity.__regid__, entity.eid))
rawvalue = cu.fetchone()[0]
if rawvalue is None: # no previous value
return self.new_fs_path(entity, attr)
return sysource._process_value(rawvalue, cu.description[0],
binarywrap=str)
def migrate_entity(self, entity, attribute):
"""migrate an entity attribute to the storage"""
entity.edited_attributes = set()
self.entity_added(entity, attribute)
session = entity._cw
source = session.repo.system_source
attrs = source.preprocess_entity(entity)
sql = source.sqlgen.update('cw_' + entity.__regid__, attrs,
['cw_eid'])
source.doexec(session, sql, attrs)
class AddFileOp(hook.Operation):
def rollback_event(self):
for filepath in self.session.transaction_data.pop('bfss_added'):
try:
unlink(filepath)
except Exception, ex:
self.error('cant remove %s: %s' % (filepath, ex))
class DeleteFileOp(hook.Operation):
def commit_event(self):
for filepath in self.session.transaction_data.pop('bfss_deleted'):
try:
unlink(filepath)
except Exception, ex:
self.error('cant remove %s: %s' % (filepath, ex))