Class: Ask::Tools::Repl::Kernel

Inherits:
Object
  • Object
show all
Defined in:
lib/ask/tools/shell/repl.rb

Overview

A single long-lived Ruby subprocess executing the kernel script.

Communicates over newline-delimited JSON on stdin/stdout. One eval at a time per kernel; concurrent calls serialize on an internal monitor.

Defined Under Namespace

Classes: DeadError, Error, TimeoutError

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(session:, ruby: "ruby") ⇒ Kernel

Returns a new instance of Kernel.



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# File 'lib/ask/tools/shell/repl.rb', line 186

def initialize(session:, ruby: "ruby")
  @session = session
  @script = File.expand_path("repl/kernel_script.rb", __dir__)
  @monitor = Monitor.new
  @last_used = Time.now
  @next_id = 0
  spawn_process(ruby)
end

Instance Attribute Details

#last_used ⇒ Time (readonly)

Returns last time an evaluation completed.

Returns:

  • (Time) —

    last time an evaluation completed



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# File 'lib/ask/tools/shell/repl.rb', line 184

def last_used
  @last_used
end

#session ⇒ String (readonly)

Returns session name this kernel belongs to.

Returns:

  • (String) —

    session name this kernel belongs to



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# File 'lib/ask/tools/shell/repl.rb', line 181

def session
  @session
end

Instance Method Details

#close ⇒ void

This method returns an undefined value.

Terminate the kernel process and close pipes. TERM is normally enough (the kernel script exits on it); KILL is the fallback for user code that overrode the trap or wedged the VM.



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# File 'lib/ask/tools/shell/repl.rb', line 244

def close
  @monitor.synchronize do
    return if @closed

    @closed = true
    if @pid
      begin
        Process.kill("TERM", @pid)
      rescue Errno::ESRCH, Errno::ECHILD
        @pid = nil
      end
      wait_for_exit(2)
      if @pid
        begin
          Process.kill("KILL", @pid)
        rescue Errno::ESRCH, Errno::ECHILD
          @pid = nil
        end
        wait_for_exit(1)
      end
    end
    @in_w.close unless @in_w.closed?
    @out_r.close unless @out_r.closed?
    @err_r.close unless @err_r.closed?
  end
  nil
end

#dead? ⇒ Boolean

Returns whether the kernel process is gone. Reaps the child if it already exited (zombies count as dead).

Returns:

  • (Boolean) —

    whether the kernel process is gone. Reaps the child if it already exited (zombies count as dead).



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# File 'lib/ask/tools/shell/repl.rb', line 202

def dead?
  return true if @closed
  return true unless @pid

  _, status = Process.waitpid(@pid, Process::WNOHANG)
  if status.nil?
    false
  else
    @pid = nil
    true
  end
rescue Errno::ECHILD, Errno::ESRCH, Errno::EINTR
  @pid = nil
  true
end

#eval(code, timeout: Repl.eval_timeout) ⇒ Hash

Evaluate code in the persistent binding.

Parameters:

  • code (String)
  • timeout (Integer) (defaults to: Repl.eval_timeout) —

    max seconds for this evaluation

Returns:

  • (Hash) —

    => String, "stdout" => String, "stderr" => String, "error" => String or nil

Raises:

  • (TimeoutError) —

    evaluation exceeded timeout; the kernel was killed and session state lost

  • (DeadError) —

    the kernel process died



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# File 'lib/ask/tools/shell/repl.rb', line 227

def eval(code, timeout: Repl.eval_timeout)
  @monitor.synchronize do
    raise DeadError, "process not running" if dead?

    id = (@next_id += 1)
    write_frame("id" => id, "code" => code)
    response = read_frame(id, timeout)
    @last_used = Time.now
    response
  end
end

#idle_seconds ⇒ Float

Returns seconds since the last evaluation.

Returns:

  • (Float) —

    seconds since the last evaluation



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# File 'lib/ask/tools/shell/repl.rb', line 196

def idle_seconds
  Time.now - @last_used
end