ruby/lib/timeout.rb

# Timeout long-running blocks
#
# == Synopsis
#
#   require 'timeout'
#   status = Timeout::timeout(5) {
#     # Something that should be interrupted if it takes more than 5 seconds...
#   }
#
# == Description
#
# Timeout provides a way to auto-terminate a potentially long-running
# operation if it hasn't finished in a fixed amount of time.
#
# Previous versions didn't use a module for namespacing, however
# #timeout is provided for backwards compatibility.  You
# should prefer Timeout#timeout instead.
#
# == Copyright
#
# Copyright:: (C) 2000  Network Applied Communication Laboratory, Inc.
# Copyright:: (C) 2000  Information-technology Promotion Agency, Japan

module Timeout
  # Raised by Timeout#timeout when the block times out.
  class Error < RuntimeError
  end
  class ExitException < ::Exception # :nodoc:
  end

  # :stopdoc:
  THIS_FILE = /\A#{Regexp.quote(__FILE__)}:/o
  CALLER_OFFSET = ((c = caller[0]) && THIS_FILE =~ c) ? 1 : 0
  # :startdoc:

  # Perform an operation in a block, timing it out if it takes longer
  # than +sec+ seconds to complete.
  #
  # +sec+:: Number of seconds to wait for the block to terminate. Any number
  #         may be used, including Floats to specify fractional seconds.
  # +klass+:: Exception Class to raise if the block fails to terminate
  #           in +sec+ seconds.  Omitting will use the default, Timeout::Error
  #
  # Returns the result of the block *if* the block completed before
  # +sec+ seconds, otherwise throws an exception, based on the value of +klass+.
  #
  # Note that this is both a method of module Timeout, so you can <tt>include
  # Timeout</tt> into your classes so they have a #timeout method, as well as
  # a module method, so you can call it directly as Timeout.timeout().
  def timeout(sec, klass = nil, immediate: false)   #:yield: +sec+
    return yield(sec) if sec == nil or sec.zero?
    exception = klass || Class.new(ExitException)
    Thread.async_interrupt_timing(exception => immediate ? :immediate : :on_blocking) do
      begin
        begin
          x = Thread.current
          y = Thread.start {
            begin
              sleep sec
            rescue => e
              x.raise e
            else
              x.raise exception, "execution expired"
            end
          }
          return yield(sec)
        ensure
          if y
            y.kill
            y.join # make sure y is dead.
          end
        end
      rescue exception => e
        rej = /\A#{Regexp.quote(__FILE__)}:#{__LINE__-4}\z/o
        (bt = e.backtrace).reject! {|m| rej =~ m}
        level = -caller(CALLER_OFFSET).size
        while THIS_FILE =~ bt[level]
          bt.delete_at(level)
          level += 1
        end
        raise if klass            # if exception class is specified, it
                                  # would be expected outside.
        raise Error, e.message, e.backtrace
      end
    end
  end

  module_function :timeout
end

# Identical to:
#
#   Timeout::timeout(n, e, &block).
#
# This method is deprecated and provided only for backwards compatibility.
# You should use Timeout#timeout instead.
def timeout(n, e = nil, &block)
  Timeout::timeout(n, e, &block)
end

# Another name for Timeout::Error, defined for backwards compatibility with
# earlier versions of timeout.rb.
TimeoutError = Timeout::Error