def _gcs_blob_chunk_generator(self, blob_name: str
) -> Generator[bytes, None, None]:
"""Downloads and generates chunks from given blob.
The base GoogleCloudStorageHook only allows downloading an entire file.
To enable handling large files this class provides a chunk-wise download of
bytes within the blob.
Args:
blob_name: Unique location within the bucket for the target blob.
Yields:
Chunks of the given blob, formatted as bytes.
Raises:
DataInConnectorError: When download failed.
"""
outio = io.BytesIO()
try:
bucket = self.get_conn().bucket(self.bucket)
file_blob = bucket.get_blob(blob_name)
except NotFound as error:
raise errors.DataInConnectorError(
error=error, msg='Failed to download the blob.',
error_num=errors.ErrorNameIDMap.GCS_HOOK_ERROR_MISSING_BLOB)
if file_blob is None:
raise errors.DataInConnectorError(
msg='Failed to download the blob.',
error_num=errors.ErrorNameIDMap.GCS_HOOK_ERROR_MISSING_BLOB)
chunks = int(file_blob.size / _DEFAULT_CHUNK_SIZE) + 1
for i in range(0, chunks):
outio.truncate(0)
outio.seek(0)
start = i * (_DEFAULT_CHUNK_SIZE + 1)
end = i * (_DEFAULT_CHUNK_SIZE + 1) + _DEFAULT_CHUNK_SIZE
if end > file_blob.size:
end = file_blob.size
try:
file_blob.download_to_file(outio, start=start, end=end)
except NotFound as error:
raise errors.DataInConnectorError(
error=error, msg='Failed to download the blob.',
error_num=errors.ErrorNameIDMap.GCS_HOOK_ERROR_MISSING_BLOB)
self.log.debug('Blob loading: {}%'.format(int(i / chunks * 100)))
yield outio.getvalue()
def events_blobs_generator(
self,
processed_blobs_generator: Generator[Tuple[str, str], None, None] = None
) -> Generator[blob.Blob, None, None]:
"""Generates all blobs from the bucket's prefix location.
Args:
processed_blobs_generator: A generator that provides the processed blob
information that helps skip read ranges.
Yields:
A generator that generates Blob objects from blob contents within a
prefix location in the bucket.
Raises:
DataInConnectorError: When listing blob in bucket returns a HttpError.
"""
try:
blob_names = self.list(bucket=self.bucket, prefix=self.prefix)
except googleapiclient_errors.HttpError as error:
raise errors.DataInConnectorError(
error=error, msg='Failed to get list of blobs from bucket.',
error_num=errors.ErrorNameIDMap.RETRIABLE_GCS_HOOK_ERROR_HTTP_ERROR)
if processed_blobs_generator is not None:
for processed_file, _ in processed_blobs_generator:
if processed_file in blob_names:
blob_names.remove(processed_file)
for blob_name in blob_names:
if not blob_name.endswith('/'):
try:
events = self.get_blob_events(blob_name)
yield blob.Blob(events=events, location=self.get_location(),
position=blob_name)
except (errors.DataInConnectorBlobParseError,
errors.DataInConnectorError) as error:
continue
def events_blobs_generator(
self,
processed_blobs_generator: Generator[Tuple[str, str], None,
None] = None
) -> Generator[blob.Blob, None, None]:
"""Generates pages of specified BigQuery table as blobs.
Args:
processed_blobs_generator: A generator that provides the processed blob
information that helps skip read ranges.
Yields:
blob: A blob object containing events from a page with length of
_DEFAULT_PAGE_SIZE from the specified BigQuery table.
Raises:
DataInConnectorError: Raised when BigQuery table data cannot be accessed.
"""
start_index = 0
total_rows = -1
bq_cursor = self.get_conn().cursor()
# Get the first row to ensure the accessibility.
try:
query_results = self._get_tabledata_with_retries(
bq_cursor=bq_cursor, start_index=start_index, max_results=1)
except googleapiclient_errors.HttpError as error:
raise errors.DataInConnectorError(
error=error,
msg=str(error),
error_num=errors.ErrorNameIDMap.
RETRIABLE_BQ_HOOK_ERROR_HTTP_ERROR)
else:
if query_results is None:
raise errors.DataInConnectorError(
msg='Unable to get any blobs in {}.'.format(self.url),
error_num=errors.ErrorNameIDMap.BQ_HOOK_ERROR_NO_BLOBS)
try:
total_rows = int(query_results.get('totalRows'))
except (AttributeError, TypeError, ValueError):
raise errors.DataInConnectorError(
msg='Unable to get total rows in {}.'.format(self.url),
error_num=errors.ErrorNameIDMap.
RETRIABLE_BQ_HOOK_ERROR_NO_TOTAL_ROWS)
processed_start, processed_end = self._get_next_range(
processed_blobs_generator)
# Get the pages of the requested table.
while start_index < total_rows:
num_rows = min(total_rows - start_index, _DEFAULT_PAGE_SIZE)
end_index = start_index + num_rows
if processed_start != -1 and processed_start < end_index:
num_rows = processed_start - start_index
if num_rows == 0:
start_index = processed_end
processed_start, processed_end = self._get_next_range(
processed_blobs_generator)
continue
try:
query_results = self._get_tabledata_with_retries(
bq_cursor=bq_cursor,
start_index=start_index,
max_results=num_rows)
except googleapiclient_errors.HttpError:
pass
else:
yield self._query_results_to_blob(query_results, start_index,
num_rows)
finally:
start_index = start_index + num_rows
def test_events_blobs_generator_raises_data_in_connector_error(self):
self.mocked_list.side_effect = errors.DataInConnectorError()
with self.assertRaises(errors.DataInConnectorError):
self.gcs_hook.events_blobs_generator().__next__()