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Contents
# encoding: utf-8
module Moped
module ReadPreference
# Encapsulates behaviour around a nearest read preference.
#
# @since 2.0.0
class Nearest
include Selectable
# Get the name for the read preference on the server side.
#
# @example Get the name of the read preference.
# nearest.name
#
# @return [ Symbol ] :nearest.
#
# @since 2.0.0
def name
:nearest
end
# Execute the provided block on the node with the lowest latency,
# allowing either primary or secondary.
#
# @example Read from the nearest node in the cluster.
# preference.with_node(cluster) do |node|
# node.command(ismaster: 1)
# end
#
# @note If tag sets are provided then selection will need to
# match the provided tags.
#
# @param [ Cluster ] cluster The cluster of nodes to select from.
# @param [ Proc ] block The block to execute on the node.
#
# @raise [ Errors::ConnectionFailure ] If no node was available in the
# cluster.
#
# @return [ Object ] The result of the block.
#
# @since 2.0.0
def with_node(cluster, &block)
with_retry(cluster) do
nearest = cluster.nodes.sort_by(&:latency).first
if nearest
block.call(nearest)
else
raise Errors::ConnectionFailure, "No nodes available to select in the cluster"
end
end
end
end
end
end
Version data entries
17 entries across 17 versions & 2 rubygems