# Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"). You # may not use this file except in compliance with the License. A copy of # the License is located at # # http://aws.amazon.com/apache2.0/ # # or in the "license" file accompanying this file. This file is # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF # ANY KIND, either express or implied. See the License for the specific # language governing permissions and limitations under the License. import logging import threading from io import BytesIO import awscrt.http import awscrt.s3 import botocore.awsrequest import botocore.session from awscrt.auth import ( AwsCredentials, AwsCredentialsProvider, AwsSigningAlgorithm, AwsSigningConfig, ) from awscrt.io import ( ClientBootstrap, ClientTlsContext, DefaultHostResolver, EventLoopGroup, TlsContextOptions, ) from awscrt.s3 import S3Client, S3RequestTlsMode, S3RequestType from botocore import UNSIGNED from botocore.compat import urlsplit from botocore.config import Config from botocore.exceptions import NoCredentialsError from s3transfer.constants import MB from s3transfer.exceptions import TransferNotDoneError from s3transfer.futures import BaseTransferFuture, BaseTransferMeta from s3transfer.manager import TransferManager from s3transfer.utils import ( CallArgs, OSUtils, get_callbacks, is_s3express_bucket, ) logger = logging.getLogger(__name__) CRT_S3_PROCESS_LOCK = None def acquire_crt_s3_process_lock(name): # Currently, the CRT S3 client performs best when there is only one # instance of it running on a host. This lock allows an application to # signal across processes whether there is another process of the same # application using the CRT S3 client and prevent spawning more than one # CRT S3 clients running on the system for that application. # # NOTE: When acquiring the CRT process lock, the lock automatically is # released when the lock object is garbage collected. So, the CRT process # lock is set as a global so that it is not unintentionally garbage # collected/released if reference of the lock is lost. global CRT_S3_PROCESS_LOCK if CRT_S3_PROCESS_LOCK is None: crt_lock = awscrt.s3.CrossProcessLock(name) try: crt_lock.acquire() except RuntimeError: # If there is another process that is holding the lock, the CRT # returns a RuntimeError. We return None here to signal that our # current process was not able to acquire the lock. return None CRT_S3_PROCESS_LOCK = crt_lock return CRT_S3_PROCESS_LOCK def create_s3_crt_client( region, crt_credentials_provider=None, num_threads=None, target_throughput=None, part_size=8 * MB, use_ssl=True, verify=None, ): """ :type region: str :param region: The region used for signing :type crt_credentials_provider: Optional[awscrt.auth.AwsCredentialsProvider] :param crt_credentials_provider: CRT AWS credentials provider to use to sign requests. If not set, requests will not be signed. :type num_threads: Optional[int] :param num_threads: Number of worker threads generated. Default is the number of processors in the machine. :type target_throughput: Optional[int] :param target_throughput: Throughput target in bytes per second. By default, CRT will automatically attempt to choose a target throughput that matches the system's maximum network throughput. Currently, if CRT is unable to determine the maximum network throughput, a fallback target throughput of ``1_250_000_000`` bytes per second (which translates to 10 gigabits per second, or 1.16 gibibytes per second) is used. To set a specific target throughput, set a value for this parameter. :type part_size: Optional[int] :param part_size: Size, in Bytes, of parts that files will be downloaded or uploaded in. :type use_ssl: boolean :param use_ssl: Whether or not to use SSL. By default, SSL is used. Note that not all services support non-ssl connections. :type verify: Optional[boolean/string] :param verify: Whether or not to verify SSL certificates. By default SSL certificates are verified. You can provide the following values: * False - do not validate SSL certificates. SSL will still be used (unless use_ssl is False), but SSL certificates will not be verified. * path/to/cert/bundle.pem - A filename of the CA cert bundle to use. Specify this argument if you want to use a custom CA cert bundle instead of the default one on your system. """ event_loop_group = EventLoopGroup(num_threads) host_resolver = DefaultHostResolver(event_loop_group) bootstrap = ClientBootstrap(event_loop_group, host_resolver) tls_connection_options = None tls_mode = ( S3RequestTlsMode.ENABLED if use_ssl else S3RequestTlsMode.DISABLED ) if verify is not None: tls_ctx_options = TlsContextOptions() if verify: tls_ctx_options.override_default_trust_store_from_path( ca_filepath=verify ) else: tls_ctx_options.verify_peer = False client_tls_option = ClientTlsContext(tls_ctx_options) tls_connection_options = client_tls_option.new_connection_options() target_gbps = _get_crt_throughput_target_gbps( provided_throughput_target_bytes=target_throughput ) return S3Client( bootstrap=bootstrap, region=region, credential_provider=crt_credentials_provider, part_size=part_size, tls_mode=tls_mode, tls_connection_options=tls_connection_options, throughput_target_gbps=target_gbps, enable_s3express=True, ) def _get_crt_throughput_target_gbps(provided_throughput_target_bytes=None): if provided_throughput_target_bytes is None: target_gbps = awscrt.s3.get_recommended_throughput_target_gbps() logger.debug( 'Recommended CRT throughput target in gbps: %s', target_gbps ) if target_gbps is None: target_gbps = 10.0 else: # NOTE: The GB constant in s3transfer is technically a gibibyte. The # GB constant is not used here because the CRT interprets gigabits # for networking as a base power of 10 # (i.e. 1000 ** 3 instead of 1024 ** 3). target_gbps = provided_throughput_target_bytes * 8 / 1_000_000_000 logger.debug('Using CRT throughput target in gbps: %s', target_gbps) return target_gbps class CRTTransferManager: ALLOWED_DOWNLOAD_ARGS = TransferManager.ALLOWED_DOWNLOAD_ARGS ALLOWED_UPLOAD_ARGS = TransferManager.ALLOWED_UPLOAD_ARGS ALLOWED_DELETE_ARGS = TransferManager.ALLOWED_DELETE_ARGS VALIDATE_SUPPORTED_BUCKET_VALUES = True _UNSUPPORTED_BUCKET_PATTERNS = TransferManager._UNSUPPORTED_BUCKET_PATTERNS def __init__(self, crt_s3_client, crt_request_serializer, osutil=None): """A transfer manager interface for Amazon S3 on CRT s3 client. :type crt_s3_client: awscrt.s3.S3Client :param crt_s3_client: The CRT s3 client, handling all the HTTP requests and functions under then hood :type crt_request_serializer: s3transfer.crt.BaseCRTRequestSerializer :param crt_request_serializer: Serializer, generates unsigned crt HTTP request. :type osutil: s3transfer.utils.OSUtils :param osutil: OSUtils object to use for os-related behavior when using with transfer manager. """ if osutil is None: self._osutil = OSUtils() self._crt_s3_client = crt_s3_client self._s3_args_creator = S3ClientArgsCreator( crt_request_serializer, self._osutil ) self._crt_exception_translator = ( crt_request_serializer.translate_crt_exception ) self._future_coordinators = [] self._semaphore = threading.Semaphore(128) # not configurable # A counter to create unique id's for each transfer submitted. self._id_counter = 0 def __enter__(self): return self def __exit__(self, exc_type, exc_value, *args): cancel = False if exc_type: cancel = True self._shutdown(cancel) def download( self, bucket, key, fileobj, extra_args=None, subscribers=None ): if extra_args is None: extra_args = {} if subscribers is None: subscribers = {} self._validate_all_known_args(extra_args, self.ALLOWED_DOWNLOAD_ARGS) self._validate_if_bucket_supported(bucket) callargs = CallArgs( bucket=bucket, key=key, fileobj=fileobj, extra_args=extra_args, subscribers=subscribers, ) return self._submit_transfer("get_object", callargs) def upload(self, fileobj, bucket, key, extra_args=None, subscribers=None): if extra_args is None: extra_args = {} if subscribers is None: subscribers = {} self._validate_all_known_args(extra_args, self.ALLOWED_UPLOAD_ARGS) self._validate_if_bucket_supported(bucket) self._validate_checksum_algorithm_supported(extra_args) callargs = CallArgs( bucket=bucket, key=key, fileobj=fileobj, extra_args=extra_args, subscribers=subscribers, ) return self._submit_transfer("put_object", callargs) def delete(self, bucket, key, extra_args=None, subscribers=None): if extra_args is None: extra_args = {} if subscribers is None: subscribers = {} self._validate_all_known_args(extra_args, self.ALLOWED_DELETE_ARGS) self._validate_if_bucket_supported(bucket) callargs = CallArgs( bucket=bucket, key=key, extra_args=extra_args, subscribers=subscribers, ) return self._submit_transfer("delete_object", callargs) def shutdown(self, cancel=False): self._shutdown(cancel) def _validate_if_bucket_supported(self, bucket): # s3 high level operations don't support some resources # (eg. S3 Object Lambda) only direct API calls are available # for such resources if self.VALIDATE_SUPPORTED_BUCKET_VALUES: for resource, pattern in self._UNSUPPORTED_BUCKET_PATTERNS.items(): match = pattern.match(bucket) if match: raise ValueError( f'TransferManager methods do not support {resource} ' 'resource. Use direct client calls instead.' ) def _validate_all_known_args(self, actual, allowed): for kwarg in actual: if kwarg not in allowed: raise ValueError( f"Invalid extra_args key '{kwarg}', " f"must be one of: {', '.join(allowed)}" ) def _validate_checksum_algorithm_supported(self, extra_args): checksum_algorithm = extra_args.get('ChecksumAlgorithm') if checksum_algorithm is None: return supported_algorithms = list(awscrt.s3.S3ChecksumAlgorithm.__members__) if checksum_algorithm.upper() not in supported_algorithms: raise ValueError( f'ChecksumAlgorithm: {checksum_algorithm} not supported. ' f'Supported algorithms are: {supported_algorithms}' ) def _cancel_transfers(self): for coordinator in self._future_coordinators: if not coordinator.done(): coordinator.cancel() def _finish_transfers(self): for coordinator in self._future_coordinators: coordinator.result() def _wait_transfers_done(self): for coordinator in self._future_coordinators: coordinator.wait_until_on_done_callbacks_complete() def _shutdown(self, cancel=False): if cancel: self._cancel_transfers() try: self._finish_transfers() except KeyboardInterrupt: self._cancel_transfers() except Exception: pass finally: self._wait_transfers_done() def _release_semaphore(self, **kwargs): self._semaphore.release() def _submit_transfer(self, request_type, call_args): on_done_after_calls = [self._release_semaphore] coordinator = CRTTransferCoordinator( transfer_id=self._id_counter, exception_translator=self._crt_exception_translator, ) components = { 'meta': CRTTransferMeta(self._id_counter, call_args), 'coordinator': coordinator, } future = CRTTransferFuture(**components) afterdone = AfterDoneHandler(coordinator) on_done_after_calls.append(afterdone) try: self._semaphore.acquire() on_queued = self._s3_args_creator.get_crt_callback( future, 'queued' ) on_queued() crt_callargs = self._s3_args_creator.get_make_request_args( request_type, call_args, coordinator, future, on_done_after_calls, ) crt_s3_request = self._crt_s3_client.make_request(**crt_callargs) except Exception as e: coordinator.set_exception(e, True) on_done = self._s3_args_creator.get_crt_callback( future, 'done', after_subscribers=on_done_after_calls ) on_done(error=e) else: coordinator.set_s3_request(crt_s3_request) self._future_coordinators.append(coordinator) self._id_counter += 1 return future class CRTTransferMeta(BaseTransferMeta): """Holds metadata about the CRTTransferFuture""" def __init__(self, transfer_id=None, call_args=None): self._transfer_id = transfer_id self._call_args = call_args self._user_context = {} @property def call_args(self): return self._call_args @property def transfer_id(self): return self._transfer_id @property def user_context(self): return self._user_context class CRTTransferFuture(BaseTransferFuture): def __init__(self, meta=None, coordinator=None): """The future associated to a submitted transfer request via CRT S3 client :type meta: s3transfer.crt.CRTTransferMeta :param meta: The metadata associated to the transfer future. :type coordinator: s3transfer.crt.CRTTransferCoordinator :param coordinator: The coordinator associated to the transfer future. """ self._meta = meta if meta is None: self._meta = CRTTransferMeta() self._coordinator = coordinator @property def meta(self): return self._meta def done(self): return self._coordinator.done() def result(self, timeout=None): self._coordinator.result(timeout) def cancel(self): self._coordinator.cancel() def set_exception(self, exception): """Sets the exception on the future.""" if not self.done(): raise TransferNotDoneError( 'set_exception can only be called once the transfer is ' 'complete.' ) self._coordinator.set_exception(exception, override=True) class BaseCRTRequestSerializer: def serialize_http_request(self, transfer_type, future): """Serialize CRT HTTP requests. :type transfer_type: string :param transfer_type: the type of transfer made, e.g 'put_object', 'get_object', 'delete_object' :type future: s3transfer.crt.CRTTransferFuture :rtype: awscrt.http.HttpRequest :returns: An unsigned HTTP request to be used for the CRT S3 client """ raise NotImplementedError('serialize_http_request()') def translate_crt_exception(self, exception): raise NotImplementedError('translate_crt_exception()') class BotocoreCRTRequestSerializer(BaseCRTRequestSerializer): def __init__(self, session, client_kwargs=None): """Serialize CRT HTTP request using botocore logic It also takes into account configuration from both the session and any keyword arguments that could be passed to `Session.create_client()` when serializing the request. :type session: botocore.session.Session :type client_kwargs: Optional[Dict[str, str]]) :param client_kwargs: The kwargs for the botocore s3 client initialization. """ self._session = session if client_kwargs is None: client_kwargs = {} self._resolve_client_config(session, client_kwargs) self._client = session.create_client(**client_kwargs) self._client.meta.events.register( 'request-created.s3.*', self._capture_http_request ) self._client.meta.events.register( 'after-call.s3.*', self._change_response_to_serialized_http_request ) self._client.meta.events.register( 'before-send.s3.*', self._make_fake_http_response ) def _resolve_client_config(self, session, client_kwargs): user_provided_config = None if session.get_default_client_config(): user_provided_config = session.get_default_client_config() if 'config' in client_kwargs: user_provided_config = client_kwargs['config'] client_config = Config(signature_version=UNSIGNED) if user_provided_config: client_config = user_provided_config.merge(client_config) client_kwargs['config'] = client_config client_kwargs["service_name"] = "s3" def _crt_request_from_aws_request(self, aws_request): url_parts = urlsplit(aws_request.url) crt_path = url_parts.path if url_parts.query: crt_path = f'{crt_path}?{url_parts.query}' headers_list = [] for name, value in aws_request.headers.items(): if isinstance(value, str): headers_list.append((name, value)) else: headers_list.append((name, str(value, 'utf-8'))) crt_headers = awscrt.http.HttpHeaders(headers_list) crt_request = awscrt.http.HttpRequest( method=aws_request.method, path=crt_path, headers=crt_headers, body_stream=aws_request.body, ) return crt_request def _convert_to_crt_http_request(self, botocore_http_request): # Logic that does CRTUtils.crt_request_from_aws_request crt_request = self._crt_request_from_aws_request(botocore_http_request) if crt_request.headers.get("host") is None: # If host is not set, set it for the request before using CRT s3 url_parts = urlsplit(botocore_http_request.url) crt_request.headers.set("host", url_parts.netloc) if crt_request.headers.get('Content-MD5') is not None: crt_request.headers.remove("Content-MD5") # In general, the CRT S3 client expects a content length header. It # only expects a missing content length header if the body is not # seekable. However, botocore does not set the content length header # for GetObject API requests and so we set the content length to zero # to meet the CRT S3 client's expectation that the content length # header is set even if there is no body. if crt_request.headers.get('Content-Length') is None: if botocore_http_request.body is None: crt_request.headers.add('Content-Length', "0") # Botocore sets the Transfer-Encoding header when it cannot determine # the content length of the request body (e.g. it's not seekable). # However, CRT does not support this header, but it supports # non-seekable bodies. So we remove this header to not cause issues # in the downstream CRT S3 request. if crt_request.headers.get('Transfer-Encoding') is not None: crt_request.headers.remove('Transfer-Encoding') return crt_request def _capture_http_request(self, request, **kwargs): request.context['http_request'] = request def _change_response_to_serialized_http_request( self, context, parsed, **kwargs ): request = context['http_request'] parsed['HTTPRequest'] = request.prepare() def _make_fake_http_response(self, request, **kwargs): return botocore.awsrequest.AWSResponse( None, 200, {}, FakeRawResponse(b""), ) def _get_botocore_http_request(self, client_method, call_args): return getattr(self._client, client_method)( Bucket=call_args.bucket, Key=call_args.key, **call_args.extra_args )['HTTPRequest'] def serialize_http_request(self, transfer_type, future): botocore_http_request = self._get_botocore_http_request( transfer_type, future.meta.call_args ) crt_request = self._convert_to_crt_http_request(botocore_http_request) return crt_request def translate_crt_exception(self, exception): if isinstance(exception, awscrt.s3.S3ResponseError): return self._translate_crt_s3_response_error(exception) else: return None def _translate_crt_s3_response_error(self, s3_response_error): status_code = s3_response_error.status_code if status_code < 301: # Botocore's exception parsing only # runs on status codes >= 301 return None headers = {k: v for k, v in s3_response_error.headers} operation_name = s3_response_error.operation_name if operation_name is not None: service_model = self._client.meta.service_model shape = service_model.operation_model(operation_name).output_shape else: shape = None response_dict = { 'headers': botocore.awsrequest.HeadersDict(headers), 'status_code': status_code, 'body': s3_response_error.body, } parsed_response = self._client._response_parser.parse( response_dict, shape=shape ) error_code = parsed_response.get("Error", {}).get("Code") error_class = self._client.exceptions.from_code(error_code) return error_class(parsed_response, operation_name=operation_name) class FakeRawResponse(BytesIO): def stream(self, amt=1024, decode_content=None): while True: chunk = self.read(amt) if not chunk: break yield chunk class BotocoreCRTCredentialsWrapper: def __init__(self, resolved_botocore_credentials): self._resolved_credentials = resolved_botocore_credentials def __call__(self): credentials = self._get_credentials().get_frozen_credentials() return AwsCredentials( credentials.access_key, credentials.secret_key, credentials.token ) def to_crt_credentials_provider(self): return AwsCredentialsProvider.new_delegate(self) def _get_credentials(self): if self._resolved_credentials is None: raise NoCredentialsError() return self._resolved_credentials class CRTTransferCoordinator: """A helper class for managing CRTTransferFuture""" def __init__( self, transfer_id=None, s3_request=None, exception_translator=None ): self.transfer_id = transfer_id self._exception_translator = exception_translator self._s3_request = s3_request self._lock = threading.Lock() self._exception = None self._crt_future = None self._done_event = threading.Event() @property def s3_request(self): return self._s3_request def set_done_callbacks_complete(self): self._done_event.set() def wait_until_on_done_callbacks_complete(self, timeout=None): self._done_event.wait(timeout) def set_exception(self, exception, override=False): with self._lock: if not self.done() or override: self._exception = exception def cancel(self): if self._s3_request: self._s3_request.cancel() def result(self, timeout=None): if self._exception: raise self._exception try: self._crt_future.result(timeout) except KeyboardInterrupt: self.cancel() self._crt_future.result(timeout) raise except Exception as e: self.handle_exception(e) finally: if self._s3_request: self._s3_request = None def handle_exception(self, exc): translated_exc = None if self._exception_translator: try: translated_exc = self._exception_translator(exc) except Exception as e: # Bail out if we hit an issue translating # and raise the original error. logger.debug("Unable to translate exception.", exc_info=e) pass if translated_exc is not None: raise translated_exc from exc else: raise exc def done(self): if self._crt_future is None: return False return self._crt_future.done() def set_s3_request(self, s3_request): self._s3_request = s3_request self._crt_future = self._s3_request.finished_future class S3ClientArgsCreator: def __init__(self, crt_request_serializer, os_utils): self._request_serializer = crt_request_serializer self._os_utils = os_utils def get_make_request_args( self, request_type, call_args, coordinator, future, on_done_after_calls ): request_args_handler = getattr( self, f'_get_make_request_args_{request_type}', self._default_get_make_request_args, ) return request_args_handler( request_type=request_type, call_args=call_args, coordinator=coordinator, future=future, on_done_before_calls=[], on_done_after_calls=on_done_after_calls, ) def get_crt_callback( self, future, callback_type, before_subscribers=None, after_subscribers=None, ): def invoke_all_callbacks(*args, **kwargs): callbacks_list = [] if before_subscribers is not None: callbacks_list += before_subscribers callbacks_list += get_callbacks(future, callback_type) if after_subscribers is not None: callbacks_list += after_subscribers for callback in callbacks_list: # The get_callbacks helper will set the first augment # by keyword, the other augments need to be set by keyword # as well if callback_type == "progress": callback(bytes_transferred=args[0]) else: callback(*args, **kwargs) return invoke_all_callbacks def _get_make_request_args_put_object( self, request_type, call_args, coordinator, future, on_done_before_calls, on_done_after_calls, ): send_filepath = None if isinstance(call_args.fileobj, str): send_filepath = call_args.fileobj data_len = self._os_utils.get_file_size(send_filepath) call_args.extra_args["ContentLength"] = data_len else: call_args.extra_args["Body"] = call_args.fileobj checksum_algorithm = call_args.extra_args.pop( 'ChecksumAlgorithm', 'CRC32' ).upper() checksum_config = awscrt.s3.S3ChecksumConfig( algorithm=awscrt.s3.S3ChecksumAlgorithm[checksum_algorithm], location=awscrt.s3.S3ChecksumLocation.TRAILER, ) # Suppress botocore's automatic MD5 calculation by setting an override # value that will get deleted in the BotocoreCRTRequestSerializer. # As part of the CRT S3 request, we request the CRT S3 client to # automatically add trailing checksums to its uploads. call_args.extra_args["ContentMD5"] = "override-to-be-removed" make_request_args = self._default_get_make_request_args( request_type=request_type, call_args=call_args, coordinator=coordinator, future=future, on_done_before_calls=on_done_before_calls, on_done_after_calls=on_done_after_calls, ) make_request_args['send_filepath'] = send_filepath make_request_args['checksum_config'] = checksum_config return make_request_args def _get_make_request_args_get_object( self, request_type, call_args, coordinator, future, on_done_before_calls, on_done_after_calls, ): recv_filepath = None on_body = None checksum_config = awscrt.s3.S3ChecksumConfig(validate_response=True) if isinstance(call_args.fileobj, str): final_filepath = call_args.fileobj recv_filepath = self._os_utils.get_temp_filename(final_filepath) on_done_before_calls.append( RenameTempFileHandler( coordinator, final_filepath, recv_filepath, self._os_utils ) ) else: on_body = OnBodyFileObjWriter(call_args.fileobj) make_request_args = self._default_get_make_request_args( request_type=request_type, call_args=call_args, coordinator=coordinator, future=future, on_done_before_calls=on_done_before_calls, on_done_after_calls=on_done_after_calls, ) make_request_args['recv_filepath'] = recv_filepath make_request_args['on_body'] = on_body make_request_args['checksum_config'] = checksum_config return make_request_args def _default_get_make_request_args( self, request_type, call_args, coordinator, future, on_done_before_calls, on_done_after_calls, ): make_request_args = { 'request': self._request_serializer.serialize_http_request( request_type, future ), 'type': getattr( S3RequestType, request_type.upper(), S3RequestType.DEFAULT ), 'on_done': self.get_crt_callback( future, 'done', on_done_before_calls, on_done_after_calls ), 'on_progress': self.get_crt_callback(future, 'progress'), } # For DEFAULT requests, CRT requires the official S3 operation name. # So transform string like "delete_object" -> "DeleteObject". if make_request_args['type'] == S3RequestType.DEFAULT: make_request_args['operation_name'] = ''.join( x.title() for x in request_type.split('_') ) if is_s3express_bucket(call_args.bucket): make_request_args['signing_config'] = AwsSigningConfig( algorithm=AwsSigningAlgorithm.V4_S3EXPRESS ) return make_request_args class RenameTempFileHandler: def __init__(self, coordinator, final_filename, temp_filename, osutil): self._coordinator = coordinator self._final_filename = final_filename self._temp_filename = temp_filename self._osutil = osutil def __call__(self, **kwargs): error = kwargs['error'] if error: self._osutil.remove_file(self._temp_filename) else: try: self._osutil.rename_file( self._temp_filename, self._final_filename ) except Exception as e: self._osutil.remove_file(self._temp_filename) # the CRT future has done already at this point self._coordinator.set_exception(e) class AfterDoneHandler: def __init__(self, coordinator): self._coordinator = coordinator def __call__(self, **kwargs): self._coordinator.set_done_callbacks_complete() class OnBodyFileObjWriter: def __init__(self, fileobj): self._fileobj = fileobj def __call__(self, chunk, **kwargs): self._fileobj.write(chunk)