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######################################################################
#
# File: test/unit/internal/transfer/downloader/test_parallel.py
#
# Copyright 2024 Backblaze Inc. All Rights Reserved.
#
# License https://www.backblaze.com/using_b2_code.html
#
######################################################################
import hashlib
from concurrent.futures import ThreadPoolExecutor
from io import BytesIO
from unittest.mock import Mock
import pytest
from requests import RequestException
def mock_download_response_factory(apiver_module, bucket, file_size: int = 0):
hasher = hashlib.sha1()
dummy_data = b'dummy'
file_content = (dummy_data * (file_size // len(dummy_data) + 1))[:file_size]
file_version = bucket.upload_bytes(file_content, f'dummy_file_{file_size}.txt')
hasher.update(file_content)
url = bucket.api.session.get_download_url_by_name(bucket.name, file_version.file_name)
response = bucket.api.services.session.download_file_from_url(url).__enter__()
return response, apiver_module.DownloadVersionFactory(bucket.api).from_response_headers(
response.headers
)
@pytest.fixture
def thread_pool():
with ThreadPoolExecutor(max_workers=10) as executor:
yield executor
@pytest.fixture
def output_file():
return BytesIO()
@pytest.fixture
def downloader(apiver_module, thread_pool):
return apiver_module.ParallelDownloader(
min_part_size=10,
force_chunk_size=5,
thread_pool=thread_pool,
)
def test_download_empty_file(apiver_module, b2api, bucket, downloader, output_file):
file_size = 0
mock_response, download_version = mock_download_response_factory(
apiver_module, bucket, file_size=file_size
)
mock_response.close = Mock(side_effect=mock_response.close)
bytes_written, hash_hex = downloader.download(
output_file, mock_response, download_version, b2api.session
)
assert bytes_written == file_size
assert hash_hex == 'da39a3ee5e6b4b0d3255bfef95601890afd80709'
assert output_file.getvalue() == b''
mock_response.close.assert_called_once()
def test_download_file(apiver_module, b2api, bucket, downloader, output_file):
file_size = 100
mock_response, download_version = mock_download_response_factory(
apiver_module, bucket, file_size=file_size
)
mock_response.close = Mock(side_effect=mock_response.close)
bytes_written, hash_hex = downloader.download(
output_file, mock_response, download_version, b2api.session
)
assert bytes_written == file_size
assert hash_hex == '7804df8c623573ccfc1993e04981006e5bc30383'
assert output_file.getvalue() == b'dummy' * 20
mock_response.close.assert_called_once()
def test_download_file__data_stream_error__in_first_response(
apiver_module, b2api, bucket, downloader, output_file
):
"""
Test that the downloader handles a stream error in the first response.
"""
file_size = 100
mock_response, download_version = mock_download_response_factory(
apiver_module, bucket, file_size=file_size
)
def iter_content(chunk_size=1, decode_unicode=False):
yield b'DUMMY'
raise RequestException('stream error')
yield # noqa
mock_response.iter_content = iter_content
bytes_written, hash_hex = downloader.download(
output_file, mock_response, download_version, b2api.session
)
assert bytes_written == file_size
assert output_file.getvalue() == b'DUMMY' + b'dummy' * 19
def test_download_file__data_stream_error__persistent_errors(
apiver_module, b2api, bucket, downloader, output_file
):
file_size = 1000
mock_response, download_version = mock_download_response_factory(
apiver_module, bucket, file_size=file_size
)
# Ensure that follow-up requests also return errors
def iter_content(chunk_size=1, decode_unicode=False):
yield b'd'
raise RequestException('stream error')
mock_response.iter_content = iter_content
bucket.api.services.session.download_file_from_url = Mock(return_value=mock_response)
with pytest.raises(RequestException):
downloader.download(output_file, mock_response, download_version, b2api.session)
def test_download_file__data_stream_error__multiple_errors_recovery(
apiver_module, b2api, bucket, downloader, output_file
):
"""Test downloader handles multiple half-failed requests and still downlaods entire file."""
# This works since each part is attempted up to 15 times before giving up
file_size = 100
mock_response, download_version = mock_download_response_factory(
apiver_module, bucket, file_size=file_size
)
def first_iter_content(chunk_size=1, decode_unicode=False):
yield mock_response.raw.read(1)
raise RequestException('stream error')
mock_response.iter_content = first_iter_content
download_func = bucket.api.services.session.download_file_from_url
def download_func_mock(*args, **kwargs):
response = download_func(*args, **kwargs).__enter__()
def iter_content(chunk_size=1, decode_unicode=False):
yield response.raw.read(1).upper()
raise RequestException('stream error')
response.iter_content = iter_content
return response
bucket.api.services.session.download_file_from_url = download_func_mock
bytes_written, hash_hex = downloader.download(
output_file, mock_response, download_version, b2api.session
)
assert bytes_written == file_size
assert output_file.getvalue() == b'dUMMY' + b'DUMMY' * 19
|
