Class: CommandRunner

Inherits:
Object show all
Defined in:
lib/carat-dev/commandrunner/commandrunner.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*command) ⇒ CommandRunner

Returns a new instance of CommandRunner.



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 5

def initialize(*command)
    @command        = command
    @child_pid      = nil
    @waiting_thread = nil

    @read_pipe        = nil
    @read_error_pipe  = nil
    @write_pipe       = nil
end

Instance Attribute Details

#child_pid ⇒ Object (readonly)

Returns the value of attribute child_pid.



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 3

def child_pid
  @child_pid
end

#command ⇒ Object (readonly)

Returns the value of attribute command.



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 2

def command
  @command
end

Instance Method Details

#closeWrite ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 15

def closeWrite
    @write_pipe.close
end

#kill ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 19

def kill
    Process.kill("KILL", @child_pid)
end

#read ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 23

def read
    return @read_pipe.read
end

#readError ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 27

def readError
    return @read_error_pipe.read
end

#run ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 31

def run
    parent_to_child_read, parent_to_child_write             = IO.pipe
    child_to_parent_read, child_to_parent_write             = IO.pipe
    child_to_parent_error_read, child_to_parent_error_write = IO.pipe

    @child_pid = fork do
        parent_to_child_write.close
        child_to_parent_read.close
        child_to_parent_error_read.close

        # Wait until parent is ready before we start doing anything
        if parent_to_child_read.readchar.chr != "R"
            raise "Unexpected input from parent"
        end

        $stdin.reopen(parent_to_child_read)
        $stdout.reopen(child_to_parent_write)
        $stderr.reopen(child_to_parent_error_write)

        exec(*@command)
    end

    @waiting_thread = Thread.new(@child_pid) do |pid|
        return_code = -1

        begin
            return_code = Process.waitpid2(pid)
        rescue SystemError
            raise "Process finished running already!"
        end
        return_code = return_code[1].exitstatus

        return_code
    end

    child_to_parent_write.close
    child_to_parent_error_write.close
    parent_to_child_read.close

    @read_pipe        = child_to_parent_read
    @read_error_pipe  = child_to_parent_error_read
    @write_pipe       = parent_to_child_write

    @write_pipe.write("R")
    @write_pipe.flush
end

#wait ⇒ Object

Waits for command to exit Returns: The return code of the program when it exited



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 82

def wait
    if not @child_pid or not @waiting_thread
        raise "Waiting for a process that has not started"
    end

    return_value = @waiting_thread.value

    @waiting_thread = nil
    @child_pid = nil

    return return_value
end

#write(string) ⇒ Object 



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# File 'lib/carat-dev/commandrunner/commandrunner.rb', line 95

def write(string)
    @write_pipe.write(string)
end