323 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			Ruby
		
	
	
	
			
		
		
	
	
			323 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			Ruby
		
	
	
	
# 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 'google/api_client/reference'
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require 'uuidtools'
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module Google
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  class APIClient
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    ##
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    # Helper class to contain a response to an individual batched call.
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    #
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    # @api private
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    class BatchedCallResponse
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      # @return [String] UUID of the call
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      attr_reader :call_id
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      # @return [Fixnum] HTTP status code
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      attr_accessor :status
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      # @return [Hash] HTTP response headers
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      attr_accessor :headers
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      # @return [String] HTTP response body
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      attr_accessor :body
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      ##
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      # Initialize the call response
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      # 
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      # @param [String] call_id
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      #   UUID of the original call
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      # @param [Fixnum] status
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      #   HTTP status
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      # @param [Hash] headers
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      #   HTTP response headers
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      # @param [#read, #to_str] body
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      #   Response 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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    # Wraps multiple API calls into a single over-the-wire HTTP request.
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    #
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    # @example
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    #
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    #     client = Google::APIClient.new
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    #     urlshortener = client.discovered_api('urlshortener')
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    #     batch = Google::APIClient::BatchRequest.new do |result|
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    #        puts result.data
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    #     end
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    # 
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    #     batch.add(:api_method => urlshortener.url.insert, :body_object => { 'longUrl' => 'http://example.com/foo' })
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    #     batch.add(:api_method => urlshortener.url.insert, :body_object => { 'longUrl' => 'http://example.com/bar' })
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    #
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    #     client.execute(batch)
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    #
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    class BatchRequest < Request
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      BATCH_BOUNDARY = "-----------RubyApiBatchRequest".freeze
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      # @api private
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      # @return [Array<(String,Google::APIClient::Request,Proc)] List of API calls in the batch
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      attr_reader :calls
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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.
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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] 
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      #   The constructed object.
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      #
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      # @yield [Google::APIClient::Result]
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      #   block to be called when result ready
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      def initialize(options = {}, &block)
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        @calls = []
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        @global_callback = block if block_given?
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        @last_auto_id = 0
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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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        options[:uri] ||= 'https://www.googleapis.com/batch'
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        options[:http_method] ||= 'POST'
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        super options
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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::Request] call 
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      #   the call to be added.
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      # @param [String] call_id
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      #   the ID to be used for this call. Must be unique
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      # @param [Proc] block
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      #   callback for this call's response.
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      #
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      # @return [Google::APIClient::BatchRequest]
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      #   the BatchRequest, for chaining
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      #
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      # @yield [Google::APIClient::Result]
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      #   block to be called when result ready
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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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        call_id ||= new_id
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        if @calls.assoc(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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        callback = block_given? ? block : @global_callback
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        @calls << [call_id, call, callback]        
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        return self
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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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      # @api private
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      #
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      # @param [Faraday::Response] response
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      #   the HTTP response.
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      def process_http_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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          _, call, callback = @calls.assoc(call_response.call_id)
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          result = Google::APIClient::Result.new(call, call_response)
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          callback.call(result) if callback
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        end
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        Google::APIClient::Result.new(self, response)
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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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      # @api private
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      #
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      # @return [String]
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      #   the request body.
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      def to_http_request
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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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        parts = @calls.map {|(call_id, call, callback)| serialize_call(call_id, call)}
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        build_multipart(parts, 'multipart/mixed', BATCH_BOUNDARY)
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        super
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      end
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      protected
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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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      # @api private
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      #
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      # @param [String] name
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      #   the name of the header to find.
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      # @param [Hash] headers
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      #   the hash of headers and their values.
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      #
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      # @return [String] 
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      #   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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      # @api private
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      #
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      # @return [String] 
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      #  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.assoc(@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 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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      # @api private
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      #
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      # @param [String] header
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      #   Content-ID header value.
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      #
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      # @return [String] 
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      #   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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      # Auxiliary method to split the headers from the body in an HTTP response.
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      #
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      # @api private
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      #
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      # @param [String] response
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      #   the response to parse.
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      #
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      # @return [Array<Hash>, String] 
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      #   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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      # @api private
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      #
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      # @param [String] call_response
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      #   the request to deserialize.
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      #
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      # @return [Google::APIClient::BatchedCallResponse] 
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      #   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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      # Serialize a single batched call for assembling the multipart message
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      #
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      # @api private
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      #
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      # @param [Google::APIClient::Request] call
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      #   the call to serialize.
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      #
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      # @return [Faraday::UploadIO] 
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      #   the serialized request
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      def serialize_call(call_id, call)
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        method, uri, headers, body = call.to_http_request
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        request = "#{method.to_s.upcase} #{Addressable::URI.parse(uri).request_uri} HTTP/1.1"
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        headers.each do |header, value|
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          request << "\r\n%s: %s" % [header, value]
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        end
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        if body
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          # TODO - CompositeIO if body is a stream 
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          request << "\r\n\r\n"
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          if body.respond_to?(:read)
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            request << body.read
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          else
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            request << body.to_s
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          end
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        end
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        Faraday::UploadIO.new(StringIO.new(request), 'application/http', 'ruby-api-request', 'Content-ID' => id_to_header(call_id))
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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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      # @api private
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      #
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      # @param [String] call_id
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      #   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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        return '<%s+%s>' % [@base_id, Addressable::URI.encode(call_id)]
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      end
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    end
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  end
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end |