module Minitest::ParalleForkFailFast

def parallel_fork_child_data(data)
  threads = {}
  data.each{|pid, read| threads[pid] = Thread.new(read, &:read)}
  results = []
  while sleep(0.01) && !threads.empty?
    threads.to_a.each do |pid, thread|
      unless thread.alive?
        threads.delete(pid)
        results << parallel_fork_data_from_marshal(thread.value)
        if @parallel_fork_stop
          # If any child failed fast, signal other children to fail fast
          threads.each_key do |pid|
            Process.kill(:USR1, pid)
          end
          # Set a flag indicating that all child processes have been signaled
          @parallel_fork_stop = :FINISHED
        end
      end
    end
  end
  results
end

def parallel_fork_data_from_marshal(data)
  data = Marshal.load(data)
  @parallel_fork_stop = true if data.pop
  data
end

def parallel_fork_data_to_marshal
  super << @parallel_fork_stop
end

def parallel_fork_run_test_suite(suite, reporter, options)
  super
  if parallel_fork_stat_reporter.results.any?{|r| !r.failure.is_a?(Minitest::Skip)}
    # At least one failure or error, mark as failing fast
    @parallel_fork_stop = true
  end
end

def parallel_fork_run_test_suites(suites, reporter, options)
  suites.each do |suite|
    parallel_fork_run_test_suite(suite, reporter, options)
    # Fail fast if this child process had a failure,
    # Or the USR1 signal was received indicating other child processes had a failure.
    break if @parallel_fork_stop
  end
end

def run_after_parallel_fork_hook(i)
  super
  Signal.trap(:USR1) do
    @parallel_fork_stop = true
  end
end