class Riffer::Runner::Threaded

# File lib/riffer/runner/threaded.rb, line 11
def initialize(max_concurrency: DEFAULT_MAX_CONCURRENCY)
  super()
  @max_concurrency = max_concurrency
end

# File lib/riffer/runner/threaded.rb, line 18
def map(items, context:, &block)
  return [] if items.empty?

  results = Array.new(items.size)
  errors = Array.new(items.size)
  queue = Queue.new
  items.each_with_index { |item, i| queue << [item, i] }

  workers = Array.new([items.size, @max_concurrency].min) do
    Thread.new do
      loop do
        pair = begin
          queue.pop(true)
        rescue ThreadError
          break
        end
        item, index = pair
        begin
          results[index] = yield(item)
        rescue StandardError => e
          errors[index] = e
        end
      end
    end
  end

  workers.each(&:join)

  first_error = errors.compact.first
  raise first_error if first_error

  results
end