# 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¶ ↑

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 lib/timeout.rb, line 172
    def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
      return yield(sec) if sec == nil or sec.zero?

      message ||= "execution expired"

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

      Timeout.ensure_timeout_thread_created
      perform = Proc.new do |exc|
        request = Request.new(Thread.current, sec, exc, message)
        QUEUE_MUTEX.synchronize do
          QUEUE << request
          CONDVAR.signal
        end
        begin
          return yield(sec)
        ensure
          request.finished
        end
      end

      if klass
        perform.call(klass)
      else
        backtrace = Error.catch(&perform)
        raise Error, message, backtrace
      end
    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 lib/timeout.rb, line 172
    def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
      return yield(sec) if sec == nil or sec.zero?

      message ||= "execution expired"

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

      Timeout.ensure_timeout_thread_created
      perform = Proc.new do |exc|
        request = Request.new(Thread.current, sec, exc, message)
        QUEUE_MUTEX.synchronize do
          QUEUE << request
          CONDVAR.signal
        end
        begin
          return yield(sec)
        ensure
          request.finished
        end
      end

      if klass
        perform.call(klass)
      else
        backtrace = Error.catch(&perform)
        raise Error, message, backtrace
      end
    end