"""Library for handling batch HTTP requests for apitools.""" import collections import email.generator as generator import email.mime.multipart as mime_multipart import email.mime.nonmultipart as mime_nonmultipart import email.parser as email_parser import httplib import itertools import StringIO import time import urllib import urlparse import uuid from googlecloudapis.apitools.base.py import exceptions from googlecloudapis.apitools.base.py import http_wrapper __all__ = [ 'BatchApiRequest', ] class RequestResponseAndHandler(collections.namedtuple( 'RequestResponseAndHandler', ['request', 'response', 'handler'])): """Container for data related to completing an HTTP request. This contains an HTTP request, its response, and a callback for handling the response from the server. Attributes: request: An http_wrapper.Request object representing the HTTP request. response: The http_wrapper.Response object returned from the server. handler: A callback function accepting two arguments, response and exception. Response is an http_wrapper.Response object, and exception is an apiclient.errors.HttpError object if an error occurred, or otherwise None. """ class BatchApiRequest(object): class ApiCall(object): """Holds request and response information for each request. ApiCalls are ultimately exposed to the client once the HTTP batch request has been completed. Attributes: http_request: A client-supplied http_wrapper.Request to be submitted to the server. response: A http_wrapper.Response object given by the server as a response to the user request, or None if an error occurred. exception: An apiclient.errors.HttpError object if an error occurred, or None. """ def __init__(self, request, retryable_codes, service, method_config): """Initialize an individual API request. Args: request: An http_wrapper.Request object. retryable_codes: A list of integer HTTP codes that can be retried. service: A service inheriting from base_api.BaseApiService. method_config: Method config for the desired API request. """ self.__retryable_codes = list( set(retryable_codes + [httplib.UNAUTHORIZED])) self.__http_response = None self.__service = service self.__method_config = method_config self.http_request = request # TODO(user): Add some validation to these fields. self.__response = None self.__exception = None @property def is_error(self): return self.exception is not None @property def response(self): return self.__response @property def exception(self): return self.__exception @property def authorization_failed(self): return (self.__http_response and ( self.__http_response.status_code == httplib.UNAUTHORIZED)) @property def terminal_state(self): return (self.__http_response and ( self.__http_response.status_code not in self.__retryable_codes)) def HandleResponse(self, http_response, exception): """Handles an incoming http response to the request in http_request. This is intended to be used as a callback function for BatchHttpRequest.Add. Args: http_response: Deserialized http_wrapper.Response object. exception: apiclient.errors.HttpError object if an error occurred. """ self.__http_response = http_response self.__exception = exception if self.terminal_state and not self.__exception: self.__response = self.__service.ProcessHttpResponse( self.__method_config, self.__http_response) def __init__(self, batch_url=None, retryable_codes=None): """Initialize a batch API request object. Args: batch_url: Base URL for batch API calls. retryable_codes: A list of integer HTTP codes that can be retried. """ self.api_requests = [] self.retryable_codes = retryable_codes or [] self.batch_url = batch_url or 'https://www.googleapis.com/batch' def Add(self, service, method, request, global_params=None): """Add a request to the batch. Args: service: A class inheriting base_api.BaseApiService. method: A string indicated desired method from the service. See the example in the class docstring. request: An input message appropriate for the specified service.method. global_params: Optional additional parameters to pass into method.PrepareHttpRequest. Returns: None """ # Retrieve the configs for the desired method and service. method_config = service.GetMethodConfig(method) upload_config = service.GetUploadConfig(method) # Prepare the HTTP Request. http_request = service.PrepareHttpRequest( method_config, request, global_params=global_params, upload_config=upload_config) # Create the request and add it to our master list. api_request = self.ApiCall( http_request, self.retryable_codes, service, method_config) self.api_requests.append(api_request) def Execute(self, http, sleep_between_polls=5, max_retries=5): """Execute all of the requests in the batch. Args: http: httplib2.Http object for use in the request. sleep_between_polls: Integer number of seconds to sleep between polls. max_retries: Max retries. Any requests that have not succeeded by this number of retries simply report the last response or exception, whatever it happened to be. Returns: List of ApiCalls. """ requests = [request for request in self.api_requests if not request.terminal_state] for attempt in xrange(max_retries): if attempt: time.sleep(sleep_between_polls) # Create a batch_http_request object and populate it with incomplete # requests. batch_http_request = BatchHttpRequest(batch_url=self.batch_url) for request in requests: batch_http_request.Add(request.http_request, request.HandleResponse) batch_http_request.Execute(http) # Collect retryable requests. requests = [request for request in self.api_requests if not request.terminal_state] if (any(request.authorization_failed for request in requests) and hasattr(http.request, 'credentials')): http.request.credentials.refresh(http) if not requests: break return self.api_requests class BatchHttpRequest(object): """Batches multiple http_wrapper.Request objects into a single request.""" def __init__(self, batch_url, callback=None): """Constructor for a BatchHttpRequest. Args: batch_url: URL to send batch requests to. callback: A callback to be called for each response, of the form callback(response, exception). The first parameter is the deserialized Response object. The second is an apiclient.errors.HttpError exception object if an HTTP error occurred while processing the request, or None if no error occurred. """ # Endpoint to which these requests are sent. self.__batch_url = batch_url # Global callback to be called for each individual response in the batch. self.__callback = callback # List of requests, responses and handlers. self.__request_response_handlers = {} # The last auto generated id. self.__last_auto_id = itertools.count() # Unique ID on which to base the Content-ID headers. self.__base_id = uuid.uuid4() def _ConvertIdToHeader(self, request_id): """Convert an id to a Content-ID header value. Args: request_id: String identifier for a individual request. Returns: A Content-ID header with the id_ encoded into it. A UUID is prepended to the value because Content-ID headers are supposed to be universally unique. """ return '<%s+%s>' % (self.__base_id, urllib.quote(request_id)) @staticmethod def _ConvertHeaderToId(header): """Convert a Content-ID header value to an id. Presumes the Content-ID header conforms to the format that _ConvertIdToHeader() returns. Args: header: A string indicating the Content-ID header value. Returns: The extracted id value. Raises: BatchError if the header is not in the expected format. """ if not (header.startswith('<') or header.endswith('>')): raise exceptions.BatchError('Invalid value for Content-ID: %s' % header) if '+' not in header: raise exceptions.BatchError('Invalid value for Content-ID: %s' % header) _, request_id = header[1:-1].rsplit('+', 1) return urllib.unquote(request_id) def _SerializeRequest(self, request): """Convert a http_wrapper.Request object into a string. Args: request: A http_wrapper.Request to serialize. Returns: The request as a string in application/http format. """ # Construct status line parsed = urlparse.urlsplit(request.url) request_line = urlparse.urlunsplit( (None, None, parsed.path, parsed.query, None)) status_line = request.http_method + ' ' + request_line + ' HTTP/1.1\n' major, minor = request.headers.get( 'content-type', 'application/json').split('/') msg = mime_nonmultipart.MIMENonMultipart(major, minor) # MIMENonMultipart adds its own Content-Type header. # Keep all of the other headers in headers. for key, value in request.headers.iteritems(): if key == 'content-type': continue msg[key] = value msg['Host'] = parsed.netloc msg.set_unixfrom(None) if request.body is not None: msg.set_payload(request.body) # Serialize the mime message. str_io = StringIO.StringIO() # maxheaderlen=0 means don't line wrap headers. gen = generator.Generator(str_io, maxheaderlen=0) gen.flatten(msg, unixfrom=False) body = str_io.getvalue() # Strip off the \n\n that the MIME lib tacks onto the end of the payload. if request.body is None: body = body[:-2] return status_line.encode('utf-8') + body def _DeserializeResponse(self, payload): """Convert string into Response and content. Args: payload: Header and body string to be deserialized. Returns: A Response object """ # Strip off the status line. status_line, payload = payload.split('\n', 1) _, status, _ = status_line.split(' ', 2) # Parse the rest of the response. parser = email_parser.Parser() msg = parser.parsestr(payload) # Get the headers. info = dict(msg) info['status'] = status # Create Response from the parsed headers. content = msg.get_payload() return http_wrapper.Response(info, content, self.__batch_url) def _NewId(self): """Create a new id. Auto incrementing number that avoids conflicts with ids already used. Returns: A new unique id string. """ return str(self.__last_auto_id.next()) def Add(self, request, callback=None): """Add a new request. Args: request: A http_wrapper.Request to add to the batch. callback: A callback to be called for this response, of the form callback(response, exception). The first parameter is the deserialized response object. The second is an apiclient.errors.HttpError exception object if an HTTP error occurred while processing the request, or None if no errors occurred. Returns: None """ self.__request_response_handlers[self._NewId()] = RequestResponseAndHandler( request, None, callback) def _Execute(self, http): """Serialize batch request, send to server, process response. Args: http: A httplib2.Http object to be used to make the request with. Raises: httplib2.HttpLib2Error if a transport error has occured. apiclient.errors.BatchError if the response is the wrong format. """ message = mime_multipart.MIMEMultipart('mixed') # Message should not write out its own headers. setattr(message, '_write_headers', lambda self: None) # Add all the individual requests. for key in self.__request_response_handlers: msg = mime_nonmultipart.MIMENonMultipart('application', 'http') msg['Content-Transfer-Encoding'] = 'binary' msg['Content-ID'] = self._ConvertIdToHeader(key) body = self._SerializeRequest( self.__request_response_handlers[key].request) msg.set_payload(body) message.attach(msg) request = http_wrapper.Request(self.__batch_url, 'POST') request.body = message.as_string() request.headers['content-type'] = ( 'multipart/mixed; boundary="%s"') % message.get_boundary() response = http_wrapper.MakeRequest(http, request) if response.status_code >= 300: raise exceptions.HttpError.FromResponse(response) # Prepend with a content-type header so Parser can handle it. header = 'content-type: %s\r\n\r\n' % response.info['content-type'] parser = email_parser.Parser() mime_response = parser.parsestr(header + response.content) if not mime_response.is_multipart(): raise exceptions.BatchError('Response not in multipart/mixed format.') for part in mime_response.get_payload(): request_id = self._ConvertHeaderToId(part['Content-ID']) response = self._DeserializeResponse(part.get_payload()) # Disable protected access because namedtuple._replace(...) # is not actually meant to be protected. self.__request_response_handlers[request_id] = ( self.__request_response_handlers[request_id]._replace( # pylint: disable=protected-access response=response)) def Execute(self, http): """Execute all the requests as a single batched HTTP request. Args: http: A httplib2.Http object to be used with the request. Returns: None Raises: BatchError if the response is the wrong format. """ self._Execute(http) for key in self.__request_response_handlers: response = self.__request_response_handlers[key].response callback = self.__request_response_handlers[key].handler exception = None if response.status_code >= 300: exception = exceptions.HttpError.FromResponse(response) if callback is not None: callback(response, exception) if self.__callback is not None: self.__callback(response, exception)