2021-11-11 11:23:49 +05:30
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# frozen_string_literal: true
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module Gitlab
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module Database
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module LoadBalancing
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# Configuration settings for a single LoadBalancer instance.
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class Configuration
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attr_accessor :hosts, :max_replication_difference,
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:max_replication_lag_time, :replica_check_interval,
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:service_discovery
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# Creates a configuration object for the given ActiveRecord model.
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def self.for_model(model)
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cfg = model.connection_db_config.configuration_hash.deep_symbolize_keys
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lb_cfg = cfg[:load_balancing] || {}
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config = new(model)
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if (diff = lb_cfg[:max_replication_difference])
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config.max_replication_difference = diff
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end
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if (lag = lb_cfg[:max_replication_lag_time])
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config.max_replication_lag_time = lag.to_f
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end
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if (interval = lb_cfg[:replica_check_interval])
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config.replica_check_interval = interval.to_f
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end
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if (hosts = lb_cfg[:hosts])
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config.hosts = hosts
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end
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discover = lb_cfg[:discover] || {}
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# We iterate over the known/default keys so we don't end up with
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# random keys in our configuration hash.
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config.service_discovery.each do |key, _|
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if (value = discover[key])
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config.service_discovery[key] = value
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end
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end
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config.reuse_primary_connection!
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config
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end
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def initialize(model, hosts = [])
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@max_replication_difference = 8.megabytes
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@max_replication_lag_time = 60.0
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@replica_check_interval = 60.0
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@model = model
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@hosts = hosts
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@service_discovery = {
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nameserver: 'localhost',
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port: 8600,
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record: nil,
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record_type: 'A',
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interval: 60,
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disconnect_timeout: 120,
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use_tcp: false
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}
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# Temporary model for GITLAB_LOAD_BALANCING_REUSE_PRIMARY_
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# To be removed with FF
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@primary_model = nil
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end
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def db_config_name
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@model.connection_db_config.name.to_sym
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end
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# With connection re-use the primary connection can be overwritten
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# to be used from different model
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def primary_connection_specification_name
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(@primary_model || @model).connection_specification_name
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end
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def primary_db_config
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(@primary_model || @model).connection_db_config
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end
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def replica_db_config
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@model.connection_db_config
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end
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def pool_size
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# The pool size may change when booting up GitLab, as GitLab enforces
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# a certain number of threads. If a Configuration is memoized, this
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# can lead to incorrect pool sizes.
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#
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# To support this scenario, we always attempt to read the pool size
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# from the model's configuration.
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@model.connection_db_config.configuration_hash[:pool] ||
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Database.default_pool_size
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end
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# Returns `true` if the use of load balancing replicas should be
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# enabled.
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#
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# This is disabled for Rake tasks to ensure e.g. database migrations
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# always produce consistent results.
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def load_balancing_enabled?
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return false if Gitlab::Runtime.rake?
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hosts.any? || service_discovery_enabled?
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end
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def service_discovery_enabled?
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service_discovery[:record].present?
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end
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# TODO: This is temporary code to allow re-use of primary connection
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# if the two connections are pointing to the same host. This is needed
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# to properly support transaction visibility.
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#
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# This behavior is required to support [Phase 3](https://gitlab.com/groups/gitlab-org/-/epics/6160#progress).
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# This method is meant to be removed as soon as it is finished.
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#
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# The remapping is done as-is:
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# export GITLAB_LOAD_BALANCING_REUSE_PRIMARY_<name-of-connection>=<new-name-of-connection>
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#
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# Ex.:
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# export GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci=main
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#
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def reuse_primary_connection!
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new_connection = ENV["GITLAB_LOAD_BALANCING_REUSE_PRIMARY_#{db_config_name}"]
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return unless new_connection.present?
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@primary_model = Gitlab::Database.database_base_models[new_connection.to_sym]
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unless @primary_model
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raise "Invalid value for 'GITLAB_LOAD_BALANCING_REUSE_PRIMARY_#{db_config_name}=#{new_connection}'"
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end
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end
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end
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end
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end
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end
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