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# frozen_string_literal: true
module Gitlab
module Database
module LoadBalancing
# Configuration settings for a single LoadBalancer instance.
class Configuration
attr_accessor :hosts, :max_replication_difference,
:max_replication_lag_time, :replica_check_interval,
:service_discovery, :model
# Creates a configuration object for the given ActiveRecord model.
def self.for_model(model)
cfg = model.connection_db_config.configuration_hash.deep_symbolize_keys
lb_cfg = cfg[:load_balancing] || {}
config = new(model)
if (diff = lb_cfg[:max_replication_difference])
config.max_replication_difference = diff
end
if (lag = lb_cfg[:max_replication_lag_time])
config.max_replication_lag_time = lag.to_f
end
if (interval = lb_cfg[:replica_check_interval])
config.replica_check_interval = interval.to_f
end
if (hosts = lb_cfg[:hosts])
config.hosts = hosts
end
discover = lb_cfg[:discover] || {}
# We iterate over the known/default keys so we don't end up with
# random keys in our configuration hash.
config.service_discovery.each do |key, _|
if (value = discover[key])
config.service_discovery[key] = value
end
end
config
end
def initialize(model, hosts = [])
@max_replication_difference = 8.megabytes
@max_replication_lag_time = 60.0
@replica_check_interval = 60.0
@model = model
@hosts = hosts
@service_discovery = {
nameserver: 'localhost',
port: 8600,
record: nil,
record_type: 'A',
interval: 60,
disconnect_timeout: 120,
use_tcp: false
}
end
def pool_size
# The pool size may change when booting up GitLab, as GitLab enforces
# a certain number of threads. If a Configuration is memoized, this
# can lead to incorrect pool sizes.
#
# To support this scenario, we always attempt to read the pool size
# from the model's configuration.
@model.connection_db_config.configuration_hash[:pool] ||
Database.default_pool_size
end
# Returns `true` if the use of load balancing replicas should be
# enabled.
#
# This is disabled for Rake tasks to ensure e.g. database migrations
# always produce consistent results.
def load_balancing_enabled?
return false if Gitlab::Runtime.rake?
hosts.any? || service_discovery_enabled?
end
def service_discovery_enabled?
service_discovery[:record].present?
end
end
end
end
end
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