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#! /usr/bin/env python
from abc import abstractmethod
class BlobHandle:
READ = 0x1
WRITE = 0x2
CREATE = 0x4
DELETE = 0x8
WRITEMETA = 0x10
def __init__(self, name, info, flag, blobclient):
self._name = name
self._info = info
self._flag = flag
self._blobclient = blobclient
self._location = self._blobclient._location
self._is_closed = False
self._deltag = False
self._written = False
self._createtag = False
self._need_commit = False
self._tmpfile = None
self._blobpath = ''.join([self._location, self._name,
'_', str(self.get_rev())])
if flag & BlobHandle.CREATE:
if not flag & BlobHandle.WRITE:
raise ValueError("invalid flag")
else:
self._need_commit = True
self._createtag = True
self._written = True
if flag & BlobHandle.WRITE:
self._tmpfile = self.gen_tmp()
def __del__(self):
self.del_tmp()
self._blobclient.close(self)
def create(self):
self._create(self.location + self._name)
def read(self, length, offset):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._flag & BlobHandle.READ:
raise Exception("Permission Denied")
return self._read(length, offset)
def write(self, data, offset):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._flag & BlobHandle.WRITE:
raise Exception("Permission Denied")
self._need_commit = True
written_bytes = self._write(data, offset)
self._written = bool(written_bytes)
self._info['size'] = self._get_size()
return written_bytes
def rename(self, newname):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._flag & BlobHandle.DELETE:
raise Exception("Permission Denied")
self._need_commit = True
def delete(self, deltag=True):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._flag & BlobHandle.DELETE:
raise Exception("Permission Denied")
self._need_commit = True
self._deltag = deltag
def close(self):
self._is_closed = True
if self._flag != BlobHandle.READ:
self._blobclient.close(self)
def get_metadata(self):
if self._is_closed:
raise Exception("This Blob is closed")
return self._info['metadata']
def set_metadata(self, metadata):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._flag & BlobHandle.WRITEMETA:
raise Exception("Permission Deniedd")
self._info['metadata'] = metadata
self._need_commit = True
def get_rev(self):
if self._is_closed:
raise Exception("This Blob is closed")
return self._info['rev']
def get_container(self):
if self._is_closed:
raise Exception("This Blob is closed")
return self._info['container']
def get_size(self):
if self._is_closed:
raise Exception("This Blob is closed")
return self._info['size']
def commit(self, flag):
if self._is_closed:
raise Exception("This Blob is closed")
if not self._need_commit:
return False
commit_info = dict()
commit_info['blobname'] = self._name
if self._deltag:
commit_info['deltag'] = True
else:
commit_info['deltag'] = False
commit_info['createtag'] = self._createtag
commit_info['info'] = self._info
commit_info['written'] = self._written
return self._blobclient.commit(commit_info, flag, self)
def copy_tmp(self):
BlobHandle.copy_file(
self._tmpfile,
''.join([self._location, self._info['container'], '_',
self._name, '_', str(self._info['rev'])])
)
pass
@abstractmethod
def gen_tmp(self):
# return tmp file path
pass
@abstractmethod
def del_tmp(self):
pass
@abstractmethod
def _read(self, length, offset):
pass
@abstractmethod
def _write(self, data, offset):
pass
@abstractmethod
def _get_size(self):
pass
@staticmethod
@abstractmethod
def copy_file(source, dest):
pass
@staticmethod
@abstractmethod
def del_blob(blobpath):
pass
|
