2020-11-24 15:15:51 +05:30
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# frozen_string_literal: true
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class IssueRebalancingService
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MAX_ISSUE_COUNT = 10_000
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2021-04-17 20:07:23 +05:30
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BATCH_SIZE = 100
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2020-11-24 15:15:51 +05:30
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TooManyIssues = Class.new(StandardError)
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def initialize(issue)
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@issue = issue
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@base = Issue.relative_positioning_query_base(issue)
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end
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def execute
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gates = [issue.project, issue.project.group].compact
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return unless gates.any? { |gate| Feature.enabled?(:rebalance_issues, gate) }
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raise TooManyIssues, "#{issue_count} issues" if issue_count > MAX_ISSUE_COUNT
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start = RelativePositioning::START_POSITION - (gaps / 2) * gap_size
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2021-03-11 19:13:27 +05:30
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if Feature.enabled?(:issue_rebalancing_optimization)
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Issue.transaction do
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assign_positions(start, indexed_ids)
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.sort_by(&:first)
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2021-04-17 20:07:23 +05:30
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.each_slice(BATCH_SIZE) do |pairs_with_position|
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2021-03-11 19:13:27 +05:30
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update_positions(pairs_with_position, 'rebalance issue positions in batches ordered by id')
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end
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end
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else
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Issue.transaction do
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2021-04-17 20:07:23 +05:30
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indexed_ids.each_slice(BATCH_SIZE) do |pairs|
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2021-03-11 19:13:27 +05:30
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pairs_with_position = assign_positions(start, pairs)
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update_positions(pairs_with_position, 'rebalance issue positions')
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end
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end
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2020-11-24 15:15:51 +05:30
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end
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end
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private
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attr_reader :issue, :base
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# rubocop: disable CodeReuse/ActiveRecord
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def indexed_ids
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base.reorder(:relative_position, :id).pluck(:id).each_with_index
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end
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# rubocop: enable CodeReuse/ActiveRecord
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2021-03-11 19:13:27 +05:30
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def assign_positions(start, pairs)
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pairs.map do |id, index|
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[id, start + (index * gap_size)]
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end
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end
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def update_positions(pairs_with_position, query_name)
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values = pairs_with_position.map do |id, index|
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"(#{id}, #{index})"
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2020-11-24 15:15:51 +05:30
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end.join(', ')
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2021-03-11 19:13:27 +05:30
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run_update_query(values, query_name)
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end
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def run_update_query(values, query_name)
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Issue.connection.exec_query(<<~SQL, query_name)
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2020-11-24 15:15:51 +05:30
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WITH cte(cte_id, new_pos) AS (
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SELECT *
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FROM (VALUES #{values}) as t (id, pos)
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)
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UPDATE #{Issue.table_name}
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SET relative_position = cte.new_pos
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FROM cte
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WHERE cte_id = id
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SQL
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end
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def issue_count
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@issue_count ||= base.count
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end
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def gaps
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issue_count - 1
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end
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def gap_size
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# We could try to split the available range over the number of gaps we need,
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# but IDEAL_DISTANCE * MAX_ISSUE_COUNT is only 0.1% of the available range,
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# so we are guaranteed not to exhaust it by using this static value.
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#
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# If we raise MAX_ISSUE_COUNT or IDEAL_DISTANCE significantly, this may
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# change!
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RelativePositioning::IDEAL_DISTANCE
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end
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end
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