Module: PPipe::Reader

Includes:
Log, Timeout
Included in:
PPipe, Methods
Defined in:
lib/parallelpipes.rb

Overview

PPipe requires a method of reading pipes that will not block even if the pipe is empty, is at eof, or has not been written to yet. configure_reader dynamically defines this method, which is called read_pipe

Reader is included in PPipe. It can also be included independently in any class

Instance Attribute Summary

Attributes included from Log

#verbosity

Instance Method Summary collapse

Methods included from Log

clean_up, io=, #log, log_file, log_file=

Instance Method Details

#configure_reader ⇒ Object

The best way of defining Reader#read_pipe is operating system dependent. Work out which is the best way and then define the method read_pipe to be this method.



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# File 'lib/parallelpipes.rb', line 951

def configure_reader
  @verbosity ||= 0  # for logging purposes
  pipes = [nil, IO.pipe]

  pipe = IO.pipe
  
  pipes[1][1].sync = true
  pipe[1].sync = true

  my_pipes = []

  pid = Kernel.fork
  
  if pid
    pipe[1].close
    my_pipes.push pipe[0]
    pipes[1][0].close
    pipes[1] = pipes[1][1]
  #      pipes[1].puts
  #      sleep 0.002
    log 'v8', 'sending pears'
    pipes[1].sync = true
    pipes[1].print('pears' + "\n")
  #      cmd = [2].pack("S")
  #      pipes[1].ioctl(5, cmd)
  #      sleep 1
    log 'v8',  'waiting for apples...'
    method = determine_read(my_pipes[0], "apples\nare\nnice\n")
    log 'v8', method
    self.class.send(:alias_method, :read_pipe, method)
    self.class.send(:alias_method, :get_line, method + :_get_line)
    my_pipes[0].close
    pipes[1].close
    return method
  else
    pipes[1][1].close
    my_pipes.push pipes[1][0]
    pipes[1] = nil
    pipe[0].close
    pipes[0] = pipe[1]
    pipes[0].sync = true
    log 'v8', pipes.inspect
  #      sleep 0.5
    log 'v8', 'waiting for pears'
    log 'v8', determine_read(my_pipes[0], "pears\n")
    
      
    log 'v8', 'sending apples'
    pipes[0].print("apples\nare\nnice" + "\n")
    pipes[0].flush
    exit
  end
end

#get_line(pipe, sep = $/) ⇒ Object

Get the next line from the pipe. Return nil if the pipe is empty or at eof. Blocks if the pipe is not empty but does not contain a complete line.



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# File 'lib/parallelpipes.rb', line 812

def get_line(pipe, sep = $/)
end

#read_pipe(pipe) ⇒ Object

Read all the contents of the pipe. Return nil if the pipe is empty. Never, ever, ever, ever block!



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# File 'lib/parallelpipes.rb', line 807

def read_pipe(pipe)
end