debian-mirror-gitlab/app/services/issue_rebalancing_service.rb
2021-09-04 02:52:04 +05:30

136 lines
4.1 KiB
Ruby

# frozen_string_literal: true
class IssueRebalancingService
MAX_ISSUE_COUNT = 10_000
BATCH_SIZE = 100
SMALLEST_BATCH_SIZE = 5
RETRIES_LIMIT = 3
TooManyIssues = Class.new(StandardError)
TIMING_CONFIGURATION = [
[0.1.seconds, 0.05.seconds], # short timings, lock_timeout: 100ms, sleep after LockWaitTimeout: 50ms
[0.5.seconds, 0.05.seconds],
[1.second, 0.5.seconds],
[1.second, 0.5.seconds],
[5.seconds, 1.second]
].freeze
def initialize(projects_collection)
@root_namespace = projects_collection.take.root_namespace # rubocop:disable CodeReuse/ActiveRecord
@base = Issue.in_projects(projects_collection)
end
def execute
return unless Feature.enabled?(:rebalance_issues, root_namespace)
raise TooManyIssues, "#{issue_count} issues" if issue_count > MAX_ISSUE_COUNT
start = RelativePositioning::START_POSITION - (gaps / 2) * gap_size
if Feature.enabled?(:issue_rebalancing_optimization)
Issue.transaction do
assign_positions(start, indexed_ids)
.sort_by(&:first)
.each_slice(BATCH_SIZE) do |pairs_with_position|
if Feature.enabled?(:issue_rebalancing_with_retry)
update_positions_with_retry(pairs_with_position, 'rebalance issue positions in batches ordered by id')
else
update_positions(pairs_with_position, 'rebalance issue positions in batches ordered by id')
end
end
end
else
Issue.transaction do
indexed_ids.each_slice(BATCH_SIZE) do |pairs|
pairs_with_position = assign_positions(start, pairs)
if Feature.enabled?(:issue_rebalancing_with_retry)
update_positions_with_retry(pairs_with_position, 'rebalance issue positions')
else
update_positions(pairs_with_position, 'rebalance issue positions')
end
end
end
end
end
private
attr_reader :root_namespace, :base
# rubocop: disable CodeReuse/ActiveRecord
def indexed_ids
base.reorder(:relative_position, :id).pluck(:id).each_with_index
end
# rubocop: enable CodeReuse/ActiveRecord
def assign_positions(start, pairs)
pairs.map do |id, index|
[id, start + (index * gap_size)]
end
end
def update_positions_with_retry(pairs_with_position, query_name)
retries = 0
batch_size = pairs_with_position.size
until pairs_with_position.empty?
begin
update_positions(pairs_with_position.first(batch_size), query_name)
pairs_with_position = pairs_with_position.drop(batch_size)
retries = 0
rescue ActiveRecord::StatementTimeout, ActiveRecord::QueryCanceled => ex
raise ex if batch_size < SMALLEST_BATCH_SIZE
if (retries += 1) == RETRIES_LIMIT
# shrink the batch size in half when RETRIES limit is reached and update still fails perhaps because batch size is still too big
batch_size = (batch_size / 2).to_i
retries = 0
end
retry
end
end
end
def update_positions(pairs_with_position, query_name)
values = pairs_with_position.map do |id, index|
"(#{id}, #{index})"
end.join(', ')
Gitlab::Database::WithLockRetries.new(timing_configuration: TIMING_CONFIGURATION, klass: self.class).run do
run_update_query(values, query_name)
end
end
def run_update_query(values, query_name)
Issue.connection.exec_query(<<~SQL, query_name)
WITH cte(cte_id, new_pos) AS #{Gitlab::Database::AsWithMaterialized.materialized_if_supported} (
SELECT *
FROM (VALUES #{values}) as t (id, pos)
)
UPDATE #{Issue.table_name}
SET relative_position = cte.new_pos
FROM cte
WHERE cte_id = id
SQL
end
def issue_count
@issue_count ||= base.count
end
def gaps
issue_count - 1
end
def gap_size
# We could try to split the available range over the number of gaps we need,
# but IDEAL_DISTANCE * MAX_ISSUE_COUNT is only 0.1% of the available range,
# so we are guaranteed not to exhaust it by using this static value.
#
# If we raise MAX_ISSUE_COUNT or IDEAL_DISTANCE significantly, this may
# change!
RelativePositioning::IDEAL_DISTANCE
end
end