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# Copyright (C) 2014-2017 MongoDB, 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.
module Mongo
module Protocol
# MongoDB Wire protocol GetMore message.
#
# This is a client request message that is sent to the server in order
# to retrieve additional documents from a cursor that has already been
# instantiated.
#
# The operation requires that you specify the database and collection
# name as well as the cursor id because cursors are scoped to a namespace.
#
# @api semipublic
class GetMore < Message
# Creates a new GetMore message
#
# @example Get 15 additional documents from cursor 123 in 'xgen.users'.
# GetMore.new('xgen', 'users', 15, 123)
#
# @param database [String, Symbol] The database to query.
# @param collection [String, Symbol] The collection to query.
# @param number_to_return [Integer] The number of documents to return.
# @param cursor_id [Integer] The cursor id returned in a reply.
def initialize(database, collection, number_to_return, cursor_id)
@database = database
@namespace = "#{database}.#{collection}"
@number_to_return = number_to_return
@cursor_id = cursor_id
@upconverter = Upconverter.new(collection, cursor_id, number_to_return)
super
end
# Return the event payload for monitoring.
#
# @example Return the event payload.
# message.payload
#
# @return [ BSON::Document ] The event payload.
#
# @since 2.1.0
def payload
BSON::Document.new(
command_name: 'getMore',
database_name: @database,
command: upconverter.command,
request_id: request_id
)
end
# Get more messages require replies from the database.
#
# @example Does the message require a reply?
# message.replyable?
#
# @return [ true ] Always true for get more.
#
# @since 2.0.0
def replyable?
true
end
protected
attr_reader :upconverter
private
# The operation code required to specify a GetMore message.
# @return [Fixnum] the operation code.
#
# @since 2.5.0
OP_CODE = 2005
# Field representing Zero encoded as an Int32
field :zero, Zero
# @!attribute
# @return [String] The namespace for this GetMore message.
field :namespace, CString
# @!attribute
# @return [Fixnum] The number to return for this GetMore message.
field :number_to_return, Int32
# @!attribute
# @return [Fixnum] The cursor id to get more documents from.
field :cursor_id, Int64
# Converts legacy getmore messages to the appropriare OP_COMMAND style
# message.
#
# @since 2.1.0
class Upconverter
# The get more constant.
#
# @since 2.2.0
GET_MORE = 'getMore'.freeze
# @return [ String ] collection The name of the collection.
attr_reader :collection
# @return [ Integer ] cursor_id The cursor id.
attr_reader :cursor_id
# @return [ Integer ] number_to_return The number of docs to return.
attr_reader :number_to_return
# Instantiate the upconverter.
#
# @example Instantiate the upconverter.
# Upconverter.new('users', 1, 1)
#
# @param [ String ] collection The name of the collection.
# @param [ Integer ] cursor_id The cursor id.
# @param [ Integer ] number_to_return The number of documents to
# return.
#
# @since 2.1.0
def initialize(collection, cursor_id, number_to_return)
@collection = collection
@cursor_id = cursor_id
@number_to_return = number_to_return
end
# Get the upconverted command.
#
# @example Get the command.
# upconverter.command
#
# @return [ BSON::Document ] The upconverted command.
#
# @since 2.1.0
def command
document = BSON::Document.new
document.store(GET_MORE, cursor_id)
document.store(Message::BATCH_SIZE, number_to_return)
document.store(Message::COLLECTION, collection)
document
end
end
Registry.register(OP_CODE, self)
end
end
end
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