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# frozen_string_literal: true
# rubocop:todo all
# Copyright (C) 2014-2020 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.
require 'mongo/collection/view/aggregation/behavior'
module Mongo
class Collection
class View
# Provides behavior around an aggregation pipeline on a collection view.
#
# @since 2.0.0
class Aggregation
include Behavior
# @return [ Array<Hash> ] pipeline The aggregation pipeline.
attr_reader :pipeline
# Initialize the aggregation for the provided collection view, pipeline
# and options.
#
# @example Create the new aggregation view.
# Aggregation.view.new(view, pipeline)
#
# @param [ Collection::View ] view The collection view.
# @param [ Array<Hash> ] pipeline The pipeline of operations.
# @param [ Hash ] options The aggregation options.
#
# @option options [ true, false ] :allow_disk_use Set to true if disk
# usage is allowed during the aggregation.
# @option options [ Integer ] :batch_size The number of documents to return
# per batch.
# @option options [ true, false ] :bypass_document_validation Whether or
# not to skip document level validation.
# @option options [ Hash ] :collation The collation to use.
# @option options [ Object ] :comment A user-provided
# comment to attach to this command.
# @option options [ String ] :hint The index to use for the aggregation.
# @option options [ Hash ] :let Mapping of variables to use in the pipeline.
# See the server documentation for details.
# @option options [ Integer ] :max_time_ms The maximum amount of time in
# milliseconds to allow the aggregation to run. This option is deprecated, use
# :timeout_ms instead.
# @option options [ Session ] :session The session to use.
# @option options [ :cursor_lifetime | :iteration ] :timeout_mode How to interpret
# :timeout_ms (whether it applies to the lifetime of the cursor, or per
# iteration).
# @option options [ Integer ] :timeout_ms The operation timeout in milliseconds.
# Must be a non-negative integer. An explicit value of 0 means infinite.
# The default value is unset which means the value is inherited from
# the collection or the database or the client.
#
# @since 2.0.0
def initialize(view, pipeline, options = {})
perform_setup(view, options) do
@pipeline = pipeline.dup
unless Mongo.broken_view_aggregate || view.filter.empty?
@pipeline.unshift(:$match => view.filter)
end
end
end
private
def new(options)
Aggregation.new(view, pipeline, options)
end
def initial_query_op(session, read_preference)
Operation::Aggregate.new(aggregate_spec(session, read_preference))
end
# Return effective read preference for the operation.
#
# If the pipeline contains $merge or $out, and read preference specified
# by user is secondary or secondary_preferred, and target server is below
# 5.0, than this method returns primary read preference, because the
# aggregation will be routed to primary. Otherwise return the original
# read preference.
#
# See https://github.com/mongodb/specifications/blob/master/source/crud/crud.md#read-preferences-and-server-selection
#
# @param [ Server::Connection ] connection The connection which
# will be used for the operation.
# @return [ Hash | nil ] read preference hash that should be sent with
# this command.
def effective_read_preference(connection)
return unless view.read_preference
return view.read_preference unless write?
return view.read_preference unless [:secondary, :secondary_preferred].include?(view.read_preference[:mode])
primary_read_preference = {mode: :primary}
description = connection.description
if description.primary?
log_warn("Routing the Aggregation operation to the primary server")
primary_read_preference
elsif description.mongos? && !description.features.merge_out_on_secondary_enabled?
log_warn("Routing the Aggregation operation to the primary server")
primary_read_preference
else
view.read_preference
end
end
def send_initial_query(server, context)
if server.load_balancer?
# Connection will be checked in when cursor is drained.
connection = server.pool.check_out(context: context)
initial_query_op(
context.session,
effective_read_preference(connection)
).execute_with_connection(
connection,
context: context
)
else
server.with_connection do |connection|
initial_query_op(
context.session,
effective_read_preference(connection)
).execute_with_connection(
connection,
context: context
)
end
end
end
end
end
end
end
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