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.
Creates a new uninitialized pipe pair.
# File lib/hydra/pipe.rb, line 34 def initialize @child_read, @parent_write = IO.pipe @parent_read, @child_write = IO.pipe end
Identify this side of the pipe as the child.
# File lib/hydra/pipe.rb, line 40 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
# File lib/hydra/pipe.rb, line 48 def identify_as_parent @child_write.close @child_read.close @reader = @parent_read @writer = @parent_write end
Output pipe nicely
# File lib/hydra/pipe.rb, line 56 def inspect "#<#{self.class} @reader=#{@reader.to_s}, @writer=#{@writer.to_s}>" end