[ruby] capture3_with_timeout

capture3_with_timeout.rb

# encoding: utf-8

require "timeout"

# Capture the standard output and the standard error of a command.
# Almost same as Open3.capture3 method except for timeout handling and return value.
# See Open3.capture3.
#
#   result = capture3_with_timeout([env,] cmd... [, opts])
#
# The arguments env, cmd and opts are passed to Process.spawn except
# opts[:stdin_data], opts[:binmode], opts[:timeout], opts[:signal]
# and opts[:kill_after].  See Process.spawn.
#
# If opts[:stdin_data] is specified, it is sent to the command's standard input.
#
# If opts[:binmode] is true, internal pipes are set to binary mode.
#
# If opts[:timeout] is specified, SIGTERM is sent to the command after specified seconds.
#
# If opts[:signal] is specified, it is used instead of SIGTERM on timeout.
#
# If opts[:kill_after] is specified, also send a SIGKILL after specified seconds.
# it is only sent if the command is still running after the initial signal was sent.
#
# The return value is a Hash as shown below.
#
#   {
#     :pid     => PID of the command,
#     :status  => Process::Status of the command,
#     :stdout  => the standard output of the command,
#     :stderr  => the standard error of the command,
#     :timeout => whether the command was timed out,
#   }
def capture3_with_timeout(*cmd)
  spawn_opts = Hash === cmd.last ? cmd.pop.dup : {}
  opts = {
    :stdin_data => spawn_opts.delete(:stdin_data) || "",
    :binmode    => spawn_opts.delete(:binmode) || false,
    :timeout    => spawn_opts.delete(:timeout),
    :signal     => spawn_opts.delete(:signal) || :TERM,
    :kill_after => spawn_opts.delete(:kill_after),
  }

  in_r,  in_w  = IO.pipe
  out_r, out_w = IO.pipe
  err_r, err_w = IO.pipe
  in_w.sync = true

  if opts[:binmode]
    in_w.binmode
    out_r.binmode
    err_r.binmode
  end

  spawn_opts[:in]  = in_r
  spawn_opts[:out] = out_w
  spawn_opts[:err] = err_w

  result = {
    :pid     => nil,
    :status  => nil,
    :stdout  => nil,
    :stderr  => nil,
    :timeout => false,
  }

  out_reader = nil
  err_reader = nil
  wait_thr = nil

  begin
    Timeout.timeout(opts[:timeout]) do
      result[:pid] = spawn(*cmd, spawn_opts)
      wait_thr = Process.detach(result[:pid])
      in_r.close
      out_w.close
      err_w.close

      out_reader = Thread.new { out_r.read }
      err_reader = Thread.new { err_r.read }

      in_w.write opts[:stdin_data]
      in_w.close

      result[:status] = wait_thr.value
    end
  rescue Timeout::Error
    result[:timeout] = true
    pid = spawn_opts[:pgroup] ? -result[:pid] : result[:pid]
    Process.kill(opts[:signal], pid)
    if opts[:kill_after]
      unless wait_thr.join(opts[:kill_after])
        Process.kill(:KILL, pid)
      end
    end
  ensure
    result[:status] = wait_thr.value if wait_thr
    result[:stdout] = out_reader.value if out_reader
    result[:stderr] = err_reader.value if err_reader
    out_r.close unless out_r.closed?
    err_r.close unless err_r.closed?
  end

  result
end