Class: Gitlab::Database::BatchCounter

Inherits:
Object
  • Object
show all
Defined in:
lib/gitlab/database/batch_counter.rb

Constant Summary collapse

FALLBACK =
-1
MIN_REQUIRED_BATCH_SIZE =
1_250
DEFAULT_SUM_BATCH_SIZE =
1_000
MAX_ALLOWED_LOOPS =
10_000
SLEEP_TIME_IN_SECONDS =

10 msec sleep

0.01
ALLOWED_MODES =
[:itself, :distinct].freeze
FALLBACK_FINISH =
0
OFFSET_BY_ONE =
1
DEFAULT_DISTINCT_BATCH_SIZE =
10_000
DEFAULT_BATCH_SIZE =
100_000

Instance Method Summary collapse

Constructor Details

#initialize(relation, column: nil, operation: :count, operation_args: nil) ⇒ BatchCounter

Returns a new instance of BatchCounter.


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# File 'lib/gitlab/database/batch_counter.rb', line 19

def initialize(relation, column: nil, operation: :count, operation_args: nil)
  @relation = relation
  @column = column || relation.primary_key
  @operation = operation
  @operation_args = operation_args
end

Instance Method Details

#count(batch_size: nil, mode: :itself, start: nil, finish: nil) ⇒ Object


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# File 'lib/gitlab/database/batch_counter.rb', line 33

def count(batch_size: nil, mode: :itself, start: nil, finish: nil)
  raise 'BatchCount can not be run inside a transaction' if transaction_open?

  check_mode!(mode)

  # non-distinct have better performance
  batch_size ||= batch_size_for_mode_and_operation(mode, @operation)

  start = actual_start(start)
  finish = actual_finish(finish)

  raise "Batch counting expects positive values only for #{@column}" if start < 0 || finish < 0
  return FALLBACK if unwanted_configuration?(finish, batch_size, start)

  results = nil
  batch_start = start

  while batch_start < finish
    begin
      batch_end = [batch_start + batch_size, finish].min
      batch_relation = build_relation_batch(batch_start, batch_end, mode)

      results = merge_results(results, batch_relation.send(@operation, *@operation_args)) # rubocop:disable GitlabSecurity/PublicSend
      batch_start = batch_end
    rescue ActiveRecord::QueryCanceled => error
      # retry with a safe batch size & warmer cache
      if batch_size >= 2 * MIN_REQUIRED_BATCH_SIZE
        batch_size /= 2
      else
        log_canceled_batch_fetch(batch_start, mode, batch_relation.to_sql, error)
        return FALLBACK
      end
    end

    sleep(SLEEP_TIME_IN_SECONDS)
  end

  results
end

#merge_results(results, object) ⇒ Object


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# File 'lib/gitlab/database/batch_counter.rb', line 77

def merge_results(results, object)
  return object unless results

  if object.is_a?(Hash)
    results.merge!(object) { |_, a, b| a + b }
  else
    results + object
  end
end

#transaction_open?Boolean

Returns:

  • (Boolean)

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# File 'lib/gitlab/database/batch_counter.rb', line 73

def transaction_open?
  @relation.connection.transaction_open?
end

#unwanted_configuration?(finish, batch_size, start) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/gitlab/database/batch_counter.rb', line 26

def unwanted_configuration?(finish, batch_size, start)
  (@operation == :count && batch_size <= MIN_REQUIRED_BATCH_SIZE) ||
    (@operation == :sum && batch_size < DEFAULT_SUM_BATCH_SIZE) ||
    (finish - start) / batch_size >= MAX_ALLOWED_LOOPS ||
    start >= finish
end