module Timeout

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

© 2000 Network Applied Communication Laboratory, Inc.

Copyright

© 2000 Information-technology Promotion Agency, Japan

Constants

VERSION

Public Class Methods

timeout(sec, klass = nil, message = nil) { |sec| ... } click to toggle source

Perform an operation in a block, raising an error 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. A value of 0 or nil will execute the block without any timeout.

klass

Exception Class to raise if the block fails to terminate in sec seconds. Omitting will use the default, Timeout::Error

message

Error message to raise with Exception Class. Omitting will use the default, “execution expired”

Returns the result of the block if the block completed before sec seconds, otherwise throws an exception, based on the value of klass.

The exception thrown to terminate the given block cannot be rescued inside the block unless klass is given explicitly. However, the block can use ensure to prevent the handling of the exception. For that reason, this method cannot be relied on to enforce timeouts for untrusted blocks.

If a scheduler is defined, it will be used to handle the timeout by invoking Scheduler#timeout_after.

Note that this is both a method of module Timeout, so you can include Timeout into your classes so they have a timeout method, as well as a module method, so you can call it directly as Timeout.timeout().

# File timeout.rb, line 83
def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
  return yield(sec) if sec == nil or sec.zero?

  message ||= "execution expired".freeze

  if Fiber.respond_to?(:current_scheduler) && (scheduler = Fiber.current_scheduler)&.respond_to?(:timeout_after)
    return scheduler.timeout_after(sec, klass || Error, message, &block)
  end

  from = "from #{caller_locations(1, 1)[0]}" if $DEBUG
  e = Error
  bl = proc do |exception|
    begin
      x = Thread.current
      y = Thread.start {
        Thread.current.name = from
        begin
          sleep sec
        rescue => e
          x.raise e
        else
          x.raise exception, message
        end
      }
      return yield(sec)
    ensure
      if y
        y.kill
        y.join # make sure y is dead.
      end
    end
  end
  if klass
    begin
      bl.call(klass)
    rescue klass => e
      message = e.message
      bt = e.backtrace
    end
  else
    bt = Error.catch(message, &bl)
  end
  level = -caller(CALLER_OFFSET).size-2
  while THIS_FILE =~ bt[level]
    bt.delete_at(level)
  end
  raise(e, message, bt)
end

Private Instance Methods

timeout(sec, klass = nil, message = nil) { |sec| ... } click to toggle source

Perform an operation in a block, raising an error 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. A value of 0 or nil will execute the block without any timeout.

klass

Exception Class to raise if the block fails to terminate in sec seconds. Omitting will use the default, Timeout::Error

message

Error message to raise with Exception Class. Omitting will use the default, “execution expired”

Returns the result of the block if the block completed before sec seconds, otherwise throws an exception, based on the value of klass.

The exception thrown to terminate the given block cannot be rescued inside the block unless klass is given explicitly. However, the block can use ensure to prevent the handling of the exception. For that reason, this method cannot be relied on to enforce timeouts for untrusted blocks.

If a scheduler is defined, it will be used to handle the timeout by invoking Scheduler#timeout_after.

Note that this is both a method of module Timeout, so you can include Timeout into your classes so they have a timeout method, as well as a module method, so you can call it directly as Timeout.timeout().

# File timeout.rb, line 83
def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
  return yield(sec) if sec == nil or sec.zero?

  message ||= "execution expired".freeze

  if Fiber.respond_to?(:current_scheduler) && (scheduler = Fiber.current_scheduler)&.respond_to?(:timeout_after)
    return scheduler.timeout_after(sec, klass || Error, message, &block)
  end

  from = "from #{caller_locations(1, 1)[0]}" if $DEBUG
  e = Error
  bl = proc do |exception|
    begin
      x = Thread.current
      y = Thread.start {
        Thread.current.name = from
        begin
          sleep sec
        rescue => e
          x.raise e
        else
          x.raise exception, message
        end
      }
      return yield(sec)
    ensure
      if y
        y.kill
        y.join # make sure y is dead.
      end
    end
  end
  if klass
    begin
      bl.call(klass)
    rescue klass => e
      message = e.message
      bt = e.backtrace
    end
  else
    bt = Error.catch(message, &bl)
  end
  level = -caller(CALLER_OFFSET).size-2
  while THIS_FILE =~ bt[level]
    bt.delete_at(level)
  end
  raise(e, message, bt)
end