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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 Operation
# Adds behaviour for updating the options and the selector for operations
# that need to take read preference into account.
#
# @since 2.0.0
module ReadPreference
include UsesCommandOpMsg
# The constant for slave ok flags.
#
# @since 2.0.6
SLAVE_OK = :slave_ok
private
def update_selector_for_read_pref(sel, server)
if read && server.mongos? && read_pref = read.to_mongos
sel = sel[:$query] ? sel : { :$query => sel }
sel.merge(:$readPreference => read_pref)
else
sel
end
end
def slave_ok?(server)
(server.cluster.single? && !server.mongos?) || (read && read.slave_ok?)
end
def update_options_for_slave_ok(opts, server)
if slave_ok?(server)
opts.dup.tap do |o|
(o[:flags] ||= []) << SLAVE_OK
end
else
opts
end
end
def message(server)
if server.features.op_msg_enabled?
command_op_msg(server, selector, options)
else
sel = update_selector_for_read_pref(selector, server)
opts = update_options_for_slave_ok(options, server)
Protocol::Query.new(db_name, query_coll, sel, opts)
end
end
end
end
end
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