ParaLines Ruby Gem

Nice output to console/file from concurrent threads:

Features:

only 170 lines of code;
no dependencies;
works on Linux and Windows;
if output to file and the script crashes in the middle — it is handled with at_exit and in the file, you will find partial output not an empty file.

Installation

gem install paralines

or in your Gemfile

gem 'paralines'

Sample with all the features (output is on the gif animation)

require 'paralines'

puts '- start -'

ParaLines.new do |plines|

    odd_line = plines.add_shared_line 'Odd: '
    even_line = plines.add_shared_line 'Even: '
    done_order_line = plines.add_shared_line 'Done order: '

    workers = (0..9).map do |n|
        Thread.new do
            if n == 0
                # special case with sub-tasks in sub-threads
                shared_line = plines.add_shared_line "Worker_#{n}: "
                (1..3).map do |sn|
                    Thread.new do
                        sleep 0.01
                        ticks_n = 5
                        part = shared_line.part_open "[subtask#{sn}…#{' '*(ticks_n-1)}] "
                        ticks_n.times do |n|
                            sleep rand
                            part.close '.' * (n+1)
                        end
                    end
                end.each &:join
                next
            else
                sleep n>5 ? 0.3 : 0.1  # make Worker_0 to be the first in the list
            end
            plines << "Worker_#{n}"
            start = Time.now
            n.odd? \
                ? (odd_part = odd_line.part_open "#{n}… ")
                : (even_part = even_line.part_open "[#{n} ")
            2.times do
                sleep rand
                plines << '.'
                fail if rand < 0.07 if !:with_fail_chanse   # remove ! here to test crashes
            end
            time = Time.now - start
            plines << "done (in %.3fs)" % time
            done_order_line << n
            odd_part&.close '+'
            even_part&.close ']'
        end
            .tap do
                if n==5
                    sleep 0.2
                    plines.add_static_line '- 5 workers added'
                elsif n==9
                    sleep 0.4
                    plines.add_static_line '- all workers added'
                end
            end
    end.each &:join

end

puts '- ready -'

Usage without a block

require 'paralines'

plines = ParaLines.new

plines.add_static_line 'Gems latest versions'
plines.add_empty_line

gems = %w[sinatra rspec paralines rails hanami]

plines.add_static_line '- Random order:'
threads = gems.map do |name|
    Thread.new do
        plines << name.ljust(15, '.')
        res = `gem list -r #{name} -e`
        plines << 'v' + res[/\((.+)\)/, 1]
    end
end
sleep 0.2
plines.add_empty_line
plines.add_static_line '- Sorted:'
threads += gems.sort.map do |name|
    sline = plines.add_shared_line name.ljust(15, '.')
    Thread.new do
        res = `gem list -r #{name} -e`
        sline << 'v' + res[/\((.+)\)/, 1]
    end
end

threads.each &:join

Contributing

Bug reports and pull requests are welcome on GitHub: https://github.com/Inversion-des/paralines

License

The gem is available as open source under the terms of the MIT License.

paralines