151 lines
		
	
	
		
			4.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
			
		
		
	
	
			151 lines
		
	
	
		
			4.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
# frozen_string_literal: true
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module Gitlab
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  module BackgroundMigration
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    # Base class for batched background migrations. Subclasses should implement the `#perform`
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    # method as the entry point for the job's execution.
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    #
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    # Job arguments needed must be defined explicitly,
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    # see https://docs.gitlab.com/ee/development/database/batched_background_migrations.html#job-arguments.
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    # rubocop:disable Metrics/ClassLength
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    # rubocop:disable Metrics/ParameterLists
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    class BatchedMigrationJob
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      include Gitlab::Database::DynamicModelHelpers
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      include Gitlab::ClassAttributes
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      DEFAULT_FEATURE_CATEGORY = :database
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      class << self
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        def generic_instance(batch_table:, batch_column:, job_arguments: [], connection:)
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          new(
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            batch_table: batch_table, batch_column: batch_column,
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            job_arguments: job_arguments, connection: connection,
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            start_id: 0, end_id: 0, sub_batch_size: 0, pause_ms: 0
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          )
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        end
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        def job_arguments_count
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          0
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        end
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        def operation_name(operation)
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          define_method(:operation_name) do
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            operation
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          end
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        end
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        def job_arguments(*args)
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          args.each.with_index do |arg, index|
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            define_method(arg) do
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              @job_arguments[index]
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            end
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          end
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          define_singleton_method(:job_arguments_count) do
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            args.count
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          end
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        end
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        def scope_to(scope)
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          define_method(:filter_batch) do |relation|
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            instance_exec(relation, &scope)
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          end
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        end
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        def feature_category(feature_category_name = nil)
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          if feature_category_name.present?
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            set_class_attribute(:feature_category, feature_category_name)
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          else
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            get_class_attribute(:feature_category) || DEFAULT_FEATURE_CATEGORY
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          end
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        end
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      end
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      def initialize(
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        start_id:, end_id:, batch_table:, batch_column:, sub_batch_size:, pause_ms:, job_arguments: [], connection:,
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        sub_batch_exception: nil
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      )
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        @start_id = start_id
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        @end_id = end_id
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        @batch_table = batch_table
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        @batch_column = batch_column
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        @sub_batch_size = sub_batch_size
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        @pause_ms = pause_ms
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        @job_arguments = job_arguments
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        @connection = connection
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        @sub_batch_exception = sub_batch_exception
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      end
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      def filter_batch(relation)
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        relation
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      end
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      def perform
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        raise NotImplementedError, "subclasses of #{self.class.name} must implement #{__method__}"
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      end
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      def batch_metrics
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        @batch_metrics ||= Gitlab::Database::BackgroundMigration::BatchMetrics.new
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      end
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      private
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      attr_reader :start_id, :end_id, :batch_table, :batch_column, :sub_batch_size,
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        :pause_ms, :connection, :sub_batch_exception
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      def each_sub_batch(batching_arguments: {}, batching_scope: nil)
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        all_batching_arguments = { column: batch_column, of: sub_batch_size }.merge(batching_arguments)
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        relation = filter_batch(base_relation)
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        sub_batch_relation = filter_sub_batch(relation, batching_scope)
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        sub_batch_relation.each_batch(**all_batching_arguments) do |relation|
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          batch_metrics.instrument_operation(operation_name) do
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            yield relation
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          rescue *Gitlab::Database::BackgroundMigration::BatchedJob::TIMEOUT_EXCEPTIONS => exception
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            exception_class = sub_batch_exception || exception.class
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            raise exception_class, exception
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          end
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          sleep([pause_ms, 0].max * 0.001)
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        end
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      end
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      def distinct_each_batch(batching_arguments: {})
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        if base_relation != filter_batch(base_relation)
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          raise 'distinct_each_batch can not be used when additional filters are defined with scope_to'
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        end
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        all_batching_arguments = { column: batch_column, of: sub_batch_size }.merge(batching_arguments)
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        base_relation.distinct_each_batch(**all_batching_arguments) do |relation|
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          batch_metrics.instrument_operation(operation_name) do
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            yield relation
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          end
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          sleep([pause_ms, 0].max * 0.001)
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        end
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      end
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      def base_relation
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        define_batchable_model(batch_table, connection: connection, primary_key: batch_column)
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          .where(batch_column => start_id..end_id)
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      end
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      def filter_sub_batch(relation, batching_scope = nil)
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        return relation unless batching_scope
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        batching_scope.call(relation)
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      end
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      def operation_name
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        raise('Operation name is required, please define it with `operation_name`')
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      end
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    end
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  end
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end
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# rubocop:enable Metrics/ClassLength
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# rubocop:enable Metrics/ParameterLists
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