Class: Cult::Paramap::Job

Inherits:
Object
  • Object
show all
Defined in:
lib/cult/paramap.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ident, value, rebind: {}, &block) ⇒ Job

Returns a new instance of Job.



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# File 'lib/cult/paramap.rb', line 24

def initialize(ident, value, rebind: {}, &block)
  @ident, @value, @rebind, @block = ident, value, rebind, block

  @pipe = IO.pipe
  @pid = fork do
    @pipe[0].close
    prepare_forked_environment!
    begin
      write_response!('=', block.call(value))
    rescue Exception => e
      write_response!('!', e)
    end
  end
  @pipe[1].close
end

Instance Attribute Details

#block ⇒ Object (readonly)

Returns the value of attribute block.



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# File 'lib/cult/paramap.rb', line 21

def block
  @block
end

#ident ⇒ Object (readonly)

Returns the value of attribute ident.



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# File 'lib/cult/paramap.rb', line 21

def ident
  @ident
end

#pid ⇒ Object (readonly)

Returns the value of attribute pid.



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# File 'lib/cult/paramap.rb', line 22

def pid
  @pid
end

#pipe ⇒ Object (readonly)

Returns the value of attribute pipe.



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# File 'lib/cult/paramap.rb', line 22

def pipe
  @pipe
end

#rebind ⇒ Object (readonly)

Returns the value of attribute rebind.



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# File 'lib/cult/paramap.rb', line 21

def rebind
  @rebind
end

#value ⇒ Object (readonly)

Returns the value of attribute value.



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# File 'lib/cult/paramap.rb', line 21

def value
  @value
end

Instance Method Details

#exception ⇒ Object 



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# File 'lib/cult/paramap.rb', line 99

def exception
  fetch_response!
  @exception
end

#fetch_response! ⇒ Object 



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# File 'lib/cult/paramap.rb', line 75

def fetch_response!
  unless pipe[0].closed?
    data = @pipe[0].read

    scode = data[0]
    fail unless ['!', '='].include?(scode)

    data = data[1..-1]
    ivar = (scode == '!') ? :exception : :result
    begin
      obj = Marshal.load(data)
    rescue
      obj = nil
    end
    instance_variable_set("@#{ivar}", obj)
    pipe[0].close
  end
end

#prepare_forked_environment! ⇒ Object 



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# File 'lib/cult/paramap.rb', line 54

def prepare_forked_environment!
  rebind_streams!
  # Stub out things that have caused a problem in the past.
  Kernel.send(:define_method, :exec) do |*a|
    fail "don't use Kernel\#exec inside of a paramap job"
  end
end

#rebind_streams! ⇒ Object 



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# File 'lib/cult/paramap.rb', line 40

def rebind_streams!
  names = {
    stdout: STDOUT,
    stdin: STDIN,
    stderr: STDERR,
    nil => '/dev/null'
  }
  rebind.each do |k, v|
    src, dst = names[k], names[v]
    dst = File.open(dst, 'w+') if dst.is_a?(String)
    src.reopen(dst)
  end
end

#result ⇒ Object 



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# File 'lib/cult/paramap.rb', line 94

def result
  fetch_response!
  @result
end

#success? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cult/paramap.rb', line 104

def success?
  exception.nil?
end

#write_response!(scode, obj) ⇒ Object 



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# File 'lib/cult/paramap.rb', line 62

def write_response!(scode, obj)
  fail unless ['!', '='].include?(scode)
  begin
    pipe[1].write(scode + Marshal.dump(obj))
  rescue TypeError => e
    # Unmarshallable
    raise unless e.message.match(/_dump_data/)
    pipe[1].write(scode + Marshal.dump(nil))
  end
  pipe[1].flush
  pipe[1].close
end