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# frozen_string_literal: true
require 'redis_client/cluster/node/base_topology'
class RedisClient
class Cluster
class Node
class RandomReplicaOrPrimary < BaseTopology
def replica_clients
keys = @replications.values.filter_map(&:sample)
@clients.select { |k, _| keys.include?(k) }
end
def clients_for_scanning(seed: nil)
random = seed.nil? ? Random : Random.new(seed)
keys = @replications.map do |primary_node_key, replica_node_keys|
decide_use_primary?(random, replica_node_keys.size) ? primary_node_key : replica_node_keys.sample(random: random)
end
clients.select { |k, _| keys.include?(k) }
end
def find_node_key_of_replica(primary_node_key, seed: nil)
random = seed.nil? ? Random : Random.new(seed)
replica_node_keys = @replications.fetch(primary_node_key, EMPTY_ARRAY)
if decide_use_primary?(random, replica_node_keys.size)
primary_node_key
else
replica_node_keys.sample(random: random) || primary_node_key
end
end
def any_replica_node_key(seed: nil)
random = seed.nil? ? Random : Random.new(seed)
@replica_node_keys.sample(random: random) || any_primary_node_key(seed: seed)
end
private
# Randomly equally likely choose node to read between primary and all replicas
# e.g. 1 primary + 1 replica = 50% probability to read from primary
# e.g. 1 primary + 2 replica = 33% probability to read from primary
# e.g. 1 primary + 0 replica = 100% probability to read from primary
def decide_use_primary?(random, replica_nodes)
primary_nodes = 1.0
total = primary_nodes + replica_nodes
random.rand < primary_nodes / total
end
end
end
end
end
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