94 lines
2.9 KiB
Ruby
94 lines
2.9 KiB
Ruby
# frozen_string_literal: true
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class BackgroundMigrationWorker # rubocop:disable Scalability/IdempotentWorker
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include ApplicationWorker
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feature_category :database
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urgency :throttled
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loggable_arguments 0, 1
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# The minimum amount of time between processing two jobs of the same migration
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# class.
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#
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# This interval is set to 2 or 5 minutes so autovacuuming and other
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# maintenance related tasks have plenty of time to clean up after a migration
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# has been performed.
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def self.minimum_interval
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2.minutes.to_i
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end
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# Performs the background migration.
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#
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# See Gitlab::BackgroundMigration.perform for more information.
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#
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# class_name - The class name of the background migration to run.
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# arguments - The arguments to pass to the migration class.
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def perform(class_name, arguments = [])
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with_context(caller_id: class_name.to_s) do
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should_perform, ttl = perform_and_ttl(class_name)
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if should_perform
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Gitlab::BackgroundMigration.perform(class_name, arguments)
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else
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# If the lease could not be obtained this means either another process is
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# running a migration of this class or we ran one recently. In this case
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# we'll reschedule the job in such a way that it is picked up again around
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# the time the lease expires.
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self.class
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.perform_in(ttl || self.class.minimum_interval, class_name, arguments)
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end
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end
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end
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def perform_and_ttl(class_name)
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if always_perform?
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# In test environments `perform_in` will run right away. This can then
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# lead to stack level errors in the above `#perform`. To work around this
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# we'll just perform the migration right away in the test environment.
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[true, nil]
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else
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lease = lease_for(class_name)
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perform = !!lease.try_obtain
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# If we managed to acquire the lease but the DB is not healthy, then we
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# want to simply reschedule our job and try again _after_ the lease
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# expires.
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if perform && !healthy_database?
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database_unhealthy_counter.increment
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perform = false
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end
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[perform, lease.ttl]
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end
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end
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def lease_for(class_name)
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Gitlab::ExclusiveLease
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.new(lease_key_for(class_name), timeout: self.class.minimum_interval)
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end
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def lease_key_for(class_name)
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"#{self.class.name}:#{class_name}"
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end
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def always_perform?
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Rails.env.test?
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end
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# Returns true if the database is healthy enough to allow the migration to be
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# performed.
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#
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# class_name - The name of the background migration that we might want to
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# run.
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def healthy_database?
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!Postgresql::ReplicationSlot.lag_too_great?
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end
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def database_unhealthy_counter
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Gitlab::Metrics.counter(
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:background_migration_database_health_reschedules,
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'The number of times a background migration is rescheduled because the database is unhealthy.'
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)
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end
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end
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