296 lines
10 KiB
Ruby
296 lines
10 KiB
Ruby
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# Copyright 2012 Google Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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require 'addressable/uri'
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require 'uuidtools'
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module Google
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class APIClient
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# Helper class to contain a response to an individual batched call.
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class BatchedCallResponse
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attr_reader :call_id
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attr_accessor :status, :headers, :body
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def initialize(call_id, status = nil, headers = nil, body = nil)
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@call_id, @status, @headers, @body = call_id, status, headers, body
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end
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end
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##
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# Wraps multiple API calls into a single over-the-wire HTTP request.
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class BatchRequest
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BATCH_BOUNDARY = "-----------RubyApiBatchRequest".freeze
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attr_accessor :options
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attr_reader :calls, :callbacks
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##
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# Creates a new batch request.
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#
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# @param [Hash] options
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# Set of options for this request, the only important one being
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# :connection, which specifies an HTTP connection to use.
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# @param [Proc] block
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# Callback for every call's response. Won't be called if a call defined
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# a callback of its own.
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#
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# @return [Google::APIClient::BatchRequest] The constructed object.
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def initialize(options = {}, &block)
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# Request options, ignoring method and parameters.
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@options = options
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# Batched calls to be made, indexed by call ID.
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@calls = {}
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# Callbacks per batched call, indexed by call ID.
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@callbacks = {}
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# Order for the call IDs, since Ruby 1.8 hashes are unordered.
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@order = []
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# Global callback to be used for every call. If a specific callback
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# has been defined for a request, this won't be called.
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@global_callback = block if block_given?
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# The last auto generated ID.
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@last_auto_id = 0
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# Base ID for the batch request.
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@base_id = nil
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end
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##
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# Add a new call to the batch request.
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# Each call must have its own call ID; if not provided, one will
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# automatically be generated, avoiding collisions. If duplicate call IDs
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# are provided, an error will be thrown.
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#
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# @param [Hash, Google::APIClient::Reference] call: the call to be added.
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# @param [String] call_id: the ID to be used for this call. Must be unique
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# @param [Proc] block: callback for this call's response.
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#
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# @return [Google::APIClient::BatchRequest] The BatchRequest, for chaining
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def add(call, call_id = nil, &block)
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unless call.kind_of?(Google::APIClient::Reference)
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call = Google::APIClient::Reference.new(call)
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end
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if call_id.nil?
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call_id = new_id
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end
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if @calls.include?(call_id)
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raise BatchError,
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'A call with this ID already exists: %s' % call_id
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end
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@calls[call_id] = call
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@order << call_id
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if block_given?
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@callbacks[call_id] = block
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elsif @global_callback
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@callbacks[call_id] = @global_callback
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end
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return self
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end
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##
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# Convert this batch request into an HTTP request.
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#
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# @return [Array<String, String, Hash, String>]
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# An array consisting of, in order: HTTP method, request path, request
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# headers and request body.
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def to_http_request
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return ['POST', request_uri, request_headers, request_body]
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end
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##
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# Processes the HTTP response to the batch request, issuing callbacks.
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#
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# @param [Faraday::Response] response: the HTTP response.
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def process_response(response)
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content_type = find_header('Content-Type', response.headers)
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boundary = /.*boundary=(.+)/.match(content_type)[1]
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parts = response.body.split(/--#{Regexp.escape(boundary)}/)
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parts = parts[1...-1]
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parts.each do |part|
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call_response = deserialize_call_response(part)
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callback = @callbacks[call_response.call_id]
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call = @calls[call_response.call_id]
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result = Google::APIClient::Result.new(call, nil, call_response)
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callback.call(result) if callback
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end
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end
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private
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##
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# Helper method to find a header from its name, regardless of case.
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#
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# @param [String] name: The name of the header to find.
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# @param [Hash] headers: The hash of headers and their values.
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#
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# @return [String] The value of the desired header.
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def find_header(name, headers)
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_, header = headers.detect do |h, v|
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h.downcase == name.downcase
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end
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return header
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end
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##
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# Create a new call ID. Uses an auto-incrementing, conflict-avoiding ID.
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#
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# @return [String] the new, unique ID.
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def new_id
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@last_auto_id += 1
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while @calls.include?(@last_auto_id)
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@last_auto_id += 1
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end
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return @last_auto_id.to_s
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end
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##
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# Convert an id to a Content-ID header value.
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#
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# @param [String] call_id: identifier of individual call.
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#
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# @return [String]
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# A Content-ID header with the call_id encoded into it. A UUID is
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# prepended to the value because Content-ID headers are supposed to be
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# universally unique.
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def id_to_header(call_id)
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if @base_id.nil?
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# TODO(sgomes): Use SecureRandom.uuid, drop UUIDTools when we drop 1.8
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@base_id = UUIDTools::UUID.random_create.to_s
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end
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return '<%s+%s>' % [@base_id, Addressable::URI.encode(call_id)]
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end
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##
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# Convert a Content-ID header value to an id. Presumes the Content-ID
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# header conforms to the format that id_to_header() returns.
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#
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# @param [String] header: Content-ID header value.
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#
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# @return [String] The extracted ID value.
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def header_to_id(header)
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if !header.start_with?('<') || !header.end_with?('>') ||
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!header.include?('+')
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raise BatchError, 'Invalid value for Content-ID: "%s"' % header
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end
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base, call_id = header[1...-1].split('+')
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return Addressable::URI.unencode(call_id)
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end
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##
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# Convert a single batched call into a string.
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#
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# @param [Google::APIClient::Reference] call: the call to serialize.
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#
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# @return [String] The request as a string in application/http format.
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def serialize_call(call)
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http_request = call.to_request
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method = http_request.method.to_s.upcase
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path = http_request.path.to_s
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status_line = method + " " + path + " HTTP/1.1"
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serialized_call = status_line
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if http_request.headers
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http_request.headers.each do |header, value|
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serialized_call << "\r\n%s: %s" % [header, value]
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end
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end
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if http_request.body
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serialized_call << "\r\n\r\n"
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serialized_call << http_request.body
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end
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return serialized_call
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end
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##
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# Auxiliary method to split the headers from the body in an HTTP response.
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#
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# @param [String] response: the response to parse.
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#
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# @return [Array<Hash>, String] The headers and the body, separately.
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def split_headers_and_body(response)
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headers = {}
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payload = response.lstrip
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while payload
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line, payload = payload.split("\n", 2)
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line.sub!(/\s+\z/, '')
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break if line.empty?
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match = /\A([^:]+):\s*/.match(line)
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if match
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headers[match[1]] = match.post_match
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else
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raise BatchError, 'Invalid header line in response: %s' % line
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end
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end
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return headers, payload
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end
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##
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# Convert a single batched response into a BatchedCallResponse object.
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#
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# @param [Google::APIClient::Reference] response:
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# the request to deserialize.
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#
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# @return [BatchedCallResponse] The parsed and converted response.
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def deserialize_call_response(call_response)
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outer_headers, outer_body = split_headers_and_body(call_response)
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status_line, payload = outer_body.split("\n", 2)
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protocol, status, reason = status_line.split(' ', 3)
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headers, body = split_headers_and_body(payload)
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content_id = find_header('Content-ID', outer_headers)
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call_id = header_to_id(content_id)
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return BatchedCallResponse.new(call_id, status.to_i, headers, body)
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end
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##
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# Return the request headers for the BatchRequest's HTTP request.
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#
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# @return [Hash] The HTTP headers.
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def request_headers
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return {
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'Content-Type' => 'multipart/mixed; boundary=%s' % BATCH_BOUNDARY
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}
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end
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##
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# Return the request path for the BatchRequest's HTTP request.
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#
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# @return [String] The request path.
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def request_uri
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if @calls.nil? || @calls.empty?
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raise BatchError, 'Cannot make an empty batch request'
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end
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# All APIs have the same batch path, so just get the first one.
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return @calls.first[1].api_method.api.batch_path
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end
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##
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# Return the request body for the BatchRequest's HTTP request.
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#
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# @return [String] The request body.
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def request_body
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body = ""
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@order.each do |call_id|
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body << "--" + BATCH_BOUNDARY + "\r\n"
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body << "Content-Type: application/http\r\n"
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body << "Content-ID: %s\r\n\r\n" % id_to_header(call_id)
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body << serialize_call(@calls[call_id]) + "\r\n\r\n"
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end
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body << "--" + BATCH_BOUNDARY + "--"
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return body
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end
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end
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end
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end
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