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Contents
require 'hydra/messaging_io'
module Hydra #:nodoc:
# Read and write between two processes via pipes. For example:
# @pipe = Hydra::Pipe.new
# @child = Process.fork do
# @pipe.identify_as_child
# puts "A message from my parent:\n#{@pipe.gets.text}"
# @pipe.close
# end
# @pipe.identify_as_parent
# @pipe.write Hydra::Messages::TestMessage.new(:text => "Hello!")
# @pipe.close
#
# Note that the TestMessage class is only available in tests, and
# not in Hydra by default.
#
#
# When the process forks, the pipe is copied. When a pipe is
# identified as a parent or child, it is choosing which ends
# of the pipe to use.
#
# A pipe is actually two pipes:
#
# Parent == Pipe 1 ==> Child
# Parent <== Pipe 2 == Child
#
# It's like if you had two cardboard tubes and you were using
# them to drop balls with messages in them between processes.
# One tube is for sending from parent to child, and the other
# tube is for sending from child to parent.
class Pipe
include Hydra::MessagingIO
# Creates a new uninitialized pipe pair.
def initialize
@child_read, @parent_write = IO.pipe
@parent_read, @child_write = IO.pipe
end
# Identify this side of the pipe as the child.
def identify_as_child
@parent_write.close
@parent_read.close
@reader = @child_read
@writer = @child_write
end
# Identify this side of the pipe as the parent
def identify_as_parent
@child_write.close
@child_read.close
@reader = @parent_read
@writer = @parent_write
end
# Output pipe nicely
def inspect
"#<#{self.class} @reader=#{@reader.to_s}, @writer=#{@writer.to_s}>"
end
end
end
Version data entries
63 entries across 63 versions & 8 rubygems