google-api-ruby-client/lib/google/api_client/batch.rb

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# Copyright 2012 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License 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.
require 'addressable/uri'
require 'google/api_client/reference'
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require 'uuidtools'
module Google
class APIClient
# Helper class to contain a response to an individual batched call.
class BatchedCallResponse
attr_reader :call_id
attr_accessor :status, :headers, :body
def initialize(call_id, status = nil, headers = nil, body = nil)
@call_id, @status, @headers, @body = call_id, status, headers, body
end
end
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##
# Wraps multiple API calls into a single over-the-wire HTTP request.
class BatchRequest < Request
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BATCH_BOUNDARY = "-----------RubyApiBatchRequest".freeze
attr_reader :calls, :callbacks
##
# Creates a new batch request.
#
# @param [Hash] options
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# Set of options for this request
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# @param [Proc] block
# Callback for every call's response. Won't be called if a call defined
# a callback of its own.
#
# @return [Google::APIClient::BatchRequest] The constructed object.
def initialize(options = {}, &block)
@calls = []
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@global_callback = block if block_given?
@last_auto_id = 0
# TODO(sgomes): Use SecureRandom.uuid, drop UUIDTools when we drop 1.8
@base_id = UUIDTools::UUID.random_create.to_s
options[:uri] ||= 'https://www.googleapis.com/batch'
options[:http_method] ||= 'POST'
super options
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end
##
# Add a new call to the batch request.
# Each call must have its own call ID; if not provided, one will
# automatically be generated, avoiding collisions. If duplicate call IDs
# are provided, an error will be thrown.
#
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# @param [Hash, Google::APIClient::Request] 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
# @param [Proc] block: callback for this call's response.
#
# @return [Google::APIClient::BatchRequest] The BatchRequest, for chaining
def add(call, call_id = nil, &block)
unless call.kind_of?(Google::APIClient::Reference)
call = Google::APIClient::Reference.new(call)
end
call_id ||= new_id
if @calls.assoc(call_id)
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raise BatchError,
'A call with this ID already exists: %s' % call_id
end
callback = block_given? ? block : @global_callback
@calls << [call_id, call, callback]
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return self
end
##
# Processes the HTTP response to the batch request, issuing callbacks.
#
# @param [Faraday::Response] response: the HTTP response.
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def process_http_response(response)
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content_type = find_header('Content-Type', response.headers)
boundary = /.*boundary=(.+)/.match(content_type)[1]
parts = response.body.split(/--#{Regexp.escape(boundary)}/)
parts = parts[1...-1]
parts.each do |part|
call_response = deserialize_call_response(part)
_, call, callback = @calls.assoc(call_response.call_id)
result = Google::APIClient::Result.new(call, call_response)
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callback.call(result) if callback
end
end
##
# Return the request body for the BatchRequest's HTTP request.
#
# @return [String] The request body.
def to_http_request
if @calls.nil? || @calls.empty?
raise BatchError, 'Cannot make an empty batch request'
end
parts = @calls.map {|(call_id, call, callback)| serialize_call(call_id, call)}
build_multipart(parts, 'multipart/mixed', BATCH_BOUNDARY)
super
end
protected
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##
# Helper method to find a header from its name, regardless of case.
#
# @param [String] name: The name of the header to find.
# @param [Hash] headers: The hash of headers and their values.
#
# @return [String] The value of the desired header.
def find_header(name, headers)
_, header = headers.detect do |h, v|
h.downcase == name.downcase
end
return header
end
##
# Create a new call ID. Uses an auto-incrementing, conflict-avoiding ID.
#
# @return [String] the new, unique ID.
def new_id
@last_auto_id += 1
while @calls.assoc(@last_auto_id)
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@last_auto_id += 1
end
return @last_auto_id.to_s
end
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##
# Convert a Content-ID header value to an id. Presumes the Content-ID
# header conforms to the format that id_to_header() returns.
#
# @param [String] header: Content-ID header value.
#
# @return [String] The extracted ID value.
def header_to_id(header)
if !header.start_with?('<') || !header.end_with?('>') ||
!header.include?('+')
raise BatchError, 'Invalid value for Content-ID: "%s"' % header
end
base, call_id = header[1...-1].split('+')
return Addressable::URI.unencode(call_id)
end
##
# Auxiliary method to split the headers from the body in an HTTP response.
#
# @param [String] response: the response to parse.
#
# @return [Array<Hash>, String] The headers and the body, separately.
def split_headers_and_body(response)
headers = {}
payload = response.lstrip
while payload
line, payload = payload.split("\n", 2)
line.sub!(/\s+\z/, '')
break if line.empty?
match = /\A([^:]+):\s*/.match(line)
if match
headers[match[1]] = match.post_match
else
raise BatchError, 'Invalid header line in response: %s' % line
end
end
return headers, payload
end
##
# Convert a single batched response into a BatchedCallResponse object.
#
# @param [Google::APIClient::Reference] response:
# the request to deserialize.
#
# @return [BatchedCallResponse] The parsed and converted response.
def deserialize_call_response(call_response)
outer_headers, outer_body = split_headers_and_body(call_response)
status_line, payload = outer_body.split("\n", 2)
protocol, status, reason = status_line.split(' ', 3)
headers, body = split_headers_and_body(payload)
content_id = find_header('Content-ID', outer_headers)
call_id = header_to_id(content_id)
return BatchedCallResponse.new(call_id, status.to_i, headers, body)
end
##
# Convert a single batched call into a string.
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#
# @param [Google::APIClient::Reference] call: the call to serialize.
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#
# @return [StringIO] The request as a string in application/http format.
def serialize_call(call_id, call)
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call.api_client = self.api_client
method, uri, headers, body = call.to_http_request
request = "#{method.to_s.upcase} #{Addressable::URI.parse(uri).path} HTTP/1.1"
headers.each do |header, value|
request << "\r\n%s: %s" % [header, value]
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end
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if body
# TODO - CompositeIO if body is a stream
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request << "\r\n\r\n"
if body.respond_to?(:read)
request << body.read
else
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request << body.to_s
end
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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##
# Convert an id to a Content-ID header value.
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#
# @param [String] call_id: identifier of individual call.
#
# @return [String]
# A Content-ID header with the call_id encoded into it. A UUID is
# prepended to the value because Content-ID headers are supposed to be
# universally unique.
def id_to_header(call_id)
return '<%s+%s>' % [@base_id, Addressable::URI.encode(call_id)]
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end
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end
end
end