# -------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for
# license information.
# --------------------------------------------------------------------------
# pylint: disable=invalid-overridden-method
import asyncio
import sys
from io import BytesIO
from itertools import islice
import warnings
from typing import AsyncIterator
from aiohttp import ClientPayloadError
from azure.core.exceptions import HttpResponseError, ServiceResponseError
from .._shared.encryption import decrypt_blob
from .._shared.request_handlers import validate_and_format_range_headers
from .._shared.response_handlers import process_storage_error, parse_length_from_content_range
from .._deserialize import get_page_ranges_result
from .._download import process_range_and_offset, _ChunkDownloader
async def process_content(data, start_offset, end_offset, encryption):
if data is None:
raise ValueError("Response cannot be None.")
content = data.response.body()
if encryption.get('key') is not None or encryption.get('resolver') is not None:
try:
return decrypt_blob(
encryption.get('required'),
encryption.get('key'),
encryption.get('resolver'),
content,
start_offset,
end_offset,
data.response.headers)
except Exception as error:
raise HttpResponseError(
message="Decryption failed.",
response=data.response,
error=error)
return content
class _AsyncChunkDownloader(_ChunkDownloader):
def __init__(self, **kwargs):
super(_AsyncChunkDownloader, self).__init__(**kwargs)
self.stream_lock = asyncio.Lock() if kwargs.get('parallel') else None
self.progress_lock = asyncio.Lock() if kwargs.get('parallel') else None
async def process_chunk(self, chunk_start):
chunk_start, chunk_end = self._calculate_range(chunk_start)
chunk_data = await self._download_chunk(chunk_start, chunk_end - 1)
length = chunk_end - chunk_start
if length > 0:
await self._write_to_stream(chunk_data, chunk_start)
await self._update_progress(length)
async def yield_chunk(self, chunk_start):
chunk_start, chunk_end = self._calculate_range(chunk_start)
return await self._download_chunk(chunk_start, chunk_end - 1)
async def _update_progress(self, length):
if self.progress_lock:
async with self.progress_lock: # pylint: disable=not-async-context-manager
self.progress_total += length
else:
self.progress_total += length
async def _write_to_stream(self, chunk_data, chunk_start):
if self.stream_lock:
async with self.stream_lock: # pylint: disable=not-async-context-manager
self.stream.seek(self.stream_start + (chunk_start - self.start_index))
self.stream.write(chunk_data)
else:
self.stream.write(chunk_data)
async def _download_chunk(self, chunk_start, chunk_end):
download_range, offset = process_range_and_offset(
chunk_start, chunk_end, chunk_end, self.encryption_options)
# No need to download the empty chunk from server if there's no data in the chunk to be downloaded.
# Do optimize and create empty chunk locally if condition is met.
if self._do_optimize(download_range[0], download_range[1]):
chunk_data = b"\x00" * self.chunk_size
else:
range_header, range_validation = validate_and_format_range_headers(
download_range[0],
download_range[1],
check_content_md5=self.validate_content
)
retry_active = True
retry_total = 3
while retry_active:
try:
_, response = await self.client.download(
range=range_header,
range_get_content_md5=range_validation,
validate_content=self.validate_content,
data_stream_total=self.total_size,
download_stream_current=self.progress_total,
**self.request_options
)
retry_active = False
except HttpResponseError as error:
process_storage_error(error)
except ClientPayloadError as error:
retry_total -= 1
if retry_total <= 0:
raise ServiceResponseError(error, error=error)
await asyncio.sleep(1)
chunk_data = await process_content(response, offset[0], offset[1], self.encryption_options)
# This makes sure that if_match is set so that we can validate
# that subsequent downloads are to an unmodified blob
if self.request_options.get('modified_access_conditions'):
self.request_options['modified_access_conditions'].if_match = response.properties.etag
return chunk_data
class _AsyncChunkIterator(object):
"""Async iterator for chunks in blob download stream."""
def __init__(self, size, content, downloader, chunk_size):
self.size = size
self._chunk_size = chunk_size
self._current_content = content
self._iter_downloader = downloader
self._iter_chunks = None
self._complete = (size == 0)
def __len__(self):
return self.size
def __iter__(self):
raise TypeError("Async stream must be iterated asynchronously.")
def __aiter__(self):
return self
async def __anext__(self):
"""Iterate through responses."""
if self._complete:
raise StopAsyncIteration("Download complete")
if not self._iter_downloader:
# cut the data obtained from initial GET into chunks
if len(self._current_content) > self._chunk_size:
return self._get_chunk_data()
self._complete = True
return self._current_content
if not self._iter_chunks:
self._iter_chunks = self._iter_downloader.get_chunk_offsets()
# initial GET result still has more than _chunk_size bytes of data
if len(self._current_content) >= self._chunk_size:
return self._get_chunk_data()
try:
chunk = next(self._iter_chunks)
self._current_content += await self._iter_downloader.yield_chunk(chunk)
except StopIteration:
self._complete = True
# it's likely that there some data left in self._current_content
if self._current_content:
return self._current_content
raise StopAsyncIteration("Download complete")
return self._get_chunk_data()
def _get_chunk_data(self):
chunk_data = self._current_content[: self._chunk_size]
self._current_content = self._current_content[self._chunk_size:]
return chunk_data
[docs]class StorageStreamDownloader(object): # pylint: disable=too-many-instance-attributes
"""A streaming object to download from Azure Storage.
:ivar str name:
The name of the blob being downloaded.
:ivar str container:
The name of the container where the blob is.
:ivar ~azure.storage.blob.BlobProperties properties:
The properties of the blob being downloaded. If only a range of the data is being
downloaded, this will be reflected in the properties.
:ivar int size:
The size of the total data in the stream. This will be the byte range if speficied,
otherwise the total size of the blob.
"""
def __init__(
self,
clients=None,
config=None,
start_range=None,
end_range=None,
validate_content=None,
encryption_options=None,
max_concurrency=1,
name=None,
container=None,
encoding=None,
**kwargs
):
self.name = name
self.container = container
self.properties = None
self.size = None
self._clients = clients
self._config = config
self._start_range = start_range
self._end_range = end_range
self._max_concurrency = max_concurrency
self._encoding = encoding
self._validate_content = validate_content
self._encryption_options = encryption_options or {}
self._request_options = kwargs
self._location_mode = None
self._download_complete = False
self._current_content = None
self._file_size = None
self._non_empty_ranges = None
self._response = None
# The service only provides transactional MD5s for chunks under 4MB.
# If validate_content is on, get only self.MAX_CHUNK_GET_SIZE for the first
# chunk so a transactional MD5 can be retrieved.
self._first_get_size = self._config.max_single_get_size if not self._validate_content \
else self._config.max_chunk_get_size
initial_request_start = self._start_range if self._start_range is not None else 0
if self._end_range is not None and self._end_range - self._start_range < self._first_get_size:
initial_request_end = self._end_range
else:
initial_request_end = initial_request_start + self._first_get_size - 1
self._initial_range, self._initial_offset = process_range_and_offset(
initial_request_start, initial_request_end, self._end_range, self._encryption_options
)
def __len__(self):
return self.size
async def _setup(self):
self._response = await self._initial_request()
self.properties = self._response.properties
self.properties.name = self.name
self.properties.container = self.container
# Set the content length to the download size instead of the size of
# the last range
self.properties.size = self.size
# Overwrite the content range to the user requested range
self.properties.content_range = 'bytes {0}-{1}/{2}'.format(
self._start_range,
self._end_range,
self._file_size
)
# Overwrite the content MD5 as it is the MD5 for the last range instead
# of the stored MD5
# TODO: Set to the stored MD5 when the service returns this
self.properties.content_md5 = None
if self.size == 0:
self._current_content = b""
else:
self._current_content = await process_content(
self._response,
self._initial_offset[0],
self._initial_offset[1],
self._encryption_options
)
async def _initial_request(self):
range_header, range_validation = validate_and_format_range_headers(
self._initial_range[0],
self._initial_range[1],
start_range_required=False,
end_range_required=False,
check_content_md5=self._validate_content)
retry_active = True
retry_total = 3
while retry_active:
try:
location_mode, response = await self._clients.blob.download(
range=range_header,
range_get_content_md5=range_validation,
validate_content=self._validate_content,
data_stream_total=None,
download_stream_current=0,
**self._request_options)
# Check the location we read from to ensure we use the same one
# for subsequent requests.
self._location_mode = location_mode
# Parse the total file size and adjust the download size if ranges
# were specified
self._file_size = parse_length_from_content_range(response.properties.content_range)
if self._end_range is not None:
# Use the length unless it is over the end of the file
self.size = min(self._file_size, self._end_range - self._start_range + 1)
elif self._start_range is not None:
self.size = self._file_size - self._start_range
else:
self.size = self._file_size
retry_active = False
except HttpResponseError as error:
if self._start_range is None and error.response.status_code == 416:
# Get range will fail on an empty file. If the user did not
# request a range, do a regular get request in order to get
# any properties.
try:
_, response = await self._clients.blob.download(
validate_content=self._validate_content,
data_stream_total=0,
download_stream_current=0,
**self._request_options)
retry_active = False
except HttpResponseError as error:
process_storage_error(error)
# Set the download size to empty
self.size = 0
self._file_size = 0
else:
process_storage_error(error)
except ClientPayloadError as error:
retry_total -= 1
if retry_total <= 0:
raise ServiceResponseError(error, error=error)
await asyncio.sleep(1)
# get page ranges to optimize downloading sparse page blob
if response.properties.blob_type == 'PageBlob':
try:
page_ranges = await self._clients.page_blob.get_page_ranges()
self._non_empty_ranges = get_page_ranges_result(page_ranges)[0]
except HttpResponseError:
pass
# If the file is small, the download is complete at this point.
# If file size is large, download the rest of the file in chunks.
if response.properties.size != self.size:
if self._request_options.get('modified_access_conditions'):
self._request_options['modified_access_conditions'].if_match = response.properties.etag
else:
self._download_complete = True
return response
[docs] def chunks(self):
# type: () -> AsyncIterator[bytes]
"""Iterate over chunks in the download stream.
:rtype: AsyncIterator[bytes]
.. admonition:: Example:
.. literalinclude:: ../samples/blob_samples_hello_world_async.py
:start-after: [START download_a_blob_in_chunk]
:end-before: [END download_a_blob_in_chunk]
:language: python
:dedent: 16
:caption: Download a blob using chunks().
"""
if self.size == 0 or self._download_complete:
iter_downloader = None
else:
data_end = self._file_size
if self._end_range is not None:
# Use the length unless it is over the end of the file
data_end = min(self._file_size, self._end_range + 1)
iter_downloader = _AsyncChunkDownloader(
client=self._clients.blob,
non_empty_ranges=self._non_empty_ranges,
total_size=self.size,
chunk_size=self._config.max_chunk_get_size,
current_progress=self._first_get_size,
start_range=self._initial_range[1] + 1, # Start where the first download ended
end_range=data_end,
stream=None,
parallel=False,
validate_content=self._validate_content,
encryption_options=self._encryption_options,
use_location=self._location_mode,
**self._request_options)
return _AsyncChunkIterator(
size=self.size,
content=self._current_content,
downloader=iter_downloader,
chunk_size=self._config.max_chunk_get_size)
[docs] async def readall(self):
"""Download the contents of this blob.
This operation is blocking until all data is downloaded.
:rtype: bytes or str
"""
stream = BytesIO()
await self.readinto(stream)
data = stream.getvalue()
if self._encoding:
return data.decode(self._encoding)
return data
[docs] async def content_as_bytes(self, max_concurrency=1):
"""Download the contents of this file.
This operation is blocking until all data is downloaded.
:keyword int max_concurrency:
The number of parallel connections with which to download.
:rtype: bytes
"""
warnings.warn(
"content_as_bytes is deprecated, use readall instead",
DeprecationWarning
)
self._max_concurrency = max_concurrency
return await self.readall()
[docs] async def content_as_text(self, max_concurrency=1, encoding="UTF-8"):
"""Download the contents of this blob, and decode as text.
This operation is blocking until all data is downloaded.
:param int max_concurrency:
The number of parallel connections with which to download.
:param str encoding:
Test encoding to decode the downloaded bytes. Default is UTF-8.
:rtype: str
"""
warnings.warn(
"content_as_text is deprecated, use readall instead",
DeprecationWarning
)
self._max_concurrency = max_concurrency
self._encoding = encoding
return await self.readall()
[docs] async def readinto(self, stream):
"""Download the contents of this blob to a stream.
:param stream:
The stream to download to. This can be an open file-handle,
or any writable stream. The stream must be seekable if the download
uses more than one parallel connection.
:returns: The number of bytes read.
:rtype: int
"""
# the stream must be seekable if parallel download is required
parallel = self._max_concurrency > 1
if parallel:
error_message = "Target stream handle must be seekable."
if sys.version_info >= (3,) and not stream.seekable():
raise ValueError(error_message)
try:
stream.seek(stream.tell())
except (NotImplementedError, AttributeError):
raise ValueError(error_message)
# Write the content to the user stream
stream.write(self._current_content)
if self._download_complete:
return self.size
data_end = self._file_size
if self._end_range is not None:
# Use the length unless it is over the end of the file
data_end = min(self._file_size, self._end_range + 1)
downloader = _AsyncChunkDownloader(
client=self._clients.blob,
non_empty_ranges=self._non_empty_ranges,
total_size=self.size,
chunk_size=self._config.max_chunk_get_size,
current_progress=self._first_get_size,
start_range=self._initial_range[1] + 1, # start where the first download ended
end_range=data_end,
stream=stream,
parallel=parallel,
validate_content=self._validate_content,
encryption_options=self._encryption_options,
use_location=self._location_mode,
**self._request_options)
dl_tasks = downloader.get_chunk_offsets()
running_futures = [
asyncio.ensure_future(downloader.process_chunk(d))
for d in islice(dl_tasks, 0, self._max_concurrency)
]
while running_futures:
# Wait for some download to finish before adding a new one
done, running_futures = await asyncio.wait(
running_futures, return_when=asyncio.FIRST_COMPLETED)
try:
for task in done:
task.result()
except HttpResponseError as error:
process_storage_error(error)
try:
next_chunk = next(dl_tasks)
except StopIteration:
break
else:
running_futures.add(asyncio.ensure_future(downloader.process_chunk(next_chunk)))
if running_futures:
# Wait for the remaining downloads to finish
done, _running_futures = await asyncio.wait(running_futures)
try:
for task in done:
task.result()
except HttpResponseError as error:
process_storage_error(error)
return self.size
[docs] async def download_to_stream(self, stream, max_concurrency=1):
"""Download the contents of this blob to a stream.
:param stream:
The stream to download to. This can be an open file-handle,
or any writable stream. The stream must be seekable if the download
uses more than one parallel connection.
:param int max_concurrency:
The number of parallel connections with which to download.
:returns: The properties of the downloaded blob.
:rtype: Any
"""
warnings.warn(
"download_to_stream is deprecated, use readinto instead",
DeprecationWarning
)
self._max_concurrency = max_concurrency
await self.readinto(stream)
return self.properties