def setup(self):
"""Seeds the index directory with empty stubs if the directory
is consistently empty. Does not overwrite existing indexes."""
absent = False
present = False
makedirs(self._index_dir)
for d in self._data_dict.values():
file_path = os.path.join(self._index_dir,
d.get_file_name())
if os.path.exists(file_path):
present = True
else:
absent = True
if absent and present:
raise search_errors.InconsistentIndexException(
self._index_dir)
if present:
return
if self.file_version_number:
raise RuntimeError("Got file_version_number other than "
"None in setup.")
self.file_version_number = INITIAL_VERSION_NUMBER
for d in self._data_dict.values():
d.write_dict_file(self._index_dir,
self.file_version_number)
def consistent_open(data_list, directory, timeout = 1):
"""Opens all data holders in data_list and ensures that the
versions are consistent among all of them.
It retries several times in case a race condition between file
migration and open is encountered.
Note: Do not set timeout to be 0. It will cause an exception to be
immediately raised.
"""
missing = None
cur_version = None
start_time = time.time()
while cur_version == None and missing != True:
# The assignments to cur_version and missing cannot be
# placed here. They must be reset prior to breaking out of the
# for loop so that the while loop condition will be true. They
# cannot be placed after the for loop since that path is taken
# when all files are missing or opened successfully.
if timeout != None and ((time.time() - start_time) > timeout):
raise search_errors.InconsistentIndexException(
directory)
for d in data_list:
# All indexes must have the same version and all must
# either be present or absent for a successful return.
# If one of these conditions is not met, the function
# tries again until it succeeds or the time spent in
# in the function is greater than timeout.
try:
f = os.path.join(directory, d.get_file_name())
fh = open(f, 'r', encoding='UTF-8')
# If we get here, then the current index file
# is present.
if missing == None:
missing = False
elif missing:
for dl in data_list:
dl.close_file_handle()
missing = None
cur_version = None
break
d.set_file_handle(fh, f)
version_tmp = fh.readline()
version_num = \
int(version_tmp.split(' ')[1].rstrip('\n'))
# Read the version. If this is the first file,
# set the expected version otherwise check that
# the version matches the expected version.
if cur_version == None:
cur_version = version_num
elif not (cur_version == version_num):
# Got inconsistent versions, so close
# all files and try again.
for d in data_list:
d.close_file_handle()
missing = None
cur_version = None
break
except IOError as e:
if e.errno == errno.ENOENT:
# If the index file is missing, ensure
# that previous files were missing as
# well. If not, try again.
if missing == False:
for d in data_list:
d.close_file_handle()
missing = None
cur_version = None
break
missing = True
else:
for d in data_list:
d.close_file_handle()
raise
if missing:
assert cur_version == None
# The index is missing (ie, no files were present).
return None
else:
assert cur_version is not None
return cur_version