Step by Step solution about How to resolve the algorithm Synchronous concurrency step by step in the Ruby programming language

The provided source code contains four different approaches to reading lines from a file and printing them along with a count of the number of lines printed.

1. The first approach uses the IO.foreach method to iterate through each line in a file. Inside the block, it prints each line and increments a counter.

2. The second approach uses a Fiber to implement a coroutine. The Fiber.yield method is used to pause the execution of the block and return the current line. The while loop then resumes the fiber and prints the line.

3. The third approach uses a Continuation to pass a control point to the block. The callcc method is used to create a continuation that can be resumed later. The block calls the continuation for each line and the while loop resumes the continuation and prints the line.

4. The fourth approach uses a Thread to perform the I/O in a separate thread. The Queue class is used to communicate between the two threads. The reader thread reads lines from the file and places them in the lines queue. The writer thread reads lines from the lines queue and prints them.

Each approach provides a different way of handling I/O and concurrency in Ruby. The best approach to use will depend on the specific requirements of the application.

count = 0
IO.foreach("input.txt") { |line| print line; count += 1 }
puts "Printed #{count} lines."


count = 0
reader = Fiber.new do
  IO.foreach("input.txt") { |line| Fiber.yield line }
  puts "Printed #{count} lines."
  nil
end

# printer
while line = reader.resume
  print line
  count += 1
end


require 'continuation' unless defined? Continuation

count = 0
reader = proc do |cont|
  IO.foreach("input.txt") { |line| cont = callcc { |cc| cont[cc, line] }}
  puts "Printed #{count} lines."
  cont[nil]
end

# printer
while array = callcc { |cc| reader[cc] }
  reader, line = array
  print line
  count += 1
end


require 'thread'

counts = Queue.new
lines = Queue.new
reader = Thread.new do
  begin
    File.foreach("input.txt") { |line| lines << line }
    lines << :EOF
    puts "Printed #{counts.pop} lines."
  ensure
    lines << nil
  end
end

# writer
count = 0
while line = lines.pop
  case line
  when String
    print line
    count += 1
  when :EOF
    counts << count
  end
end
reader.join