1# frozen_string_literal: false
2# Timeout long-running blocks
3#
4# == Synopsis
5#
6#   require 'timeout'
7#   status = Timeout::timeout(5) {
8#     # Something that should be interrupted if it takes more than 5 seconds...
9#   }
10#
11# == Description
12#
13# Timeout provides a way to auto-terminate a potentially long-running
14# operation if it hasn't finished in a fixed amount of time.
15#
16# Previous versions didn't use a module for namespacing, however
17# #timeout is provided for backwards compatibility.  You
18# should prefer Timeout.timeout instead.
19#
20# == Copyright
21#
22# Copyright:: (C) 2000  Network Applied Communication Laboratory, Inc.
23# Copyright:: (C) 2000  Information-technology Promotion Agency, Japan
24
25module Timeout
26  # Raised by Timeout.timeout when the block times out.
27  class Error < RuntimeError
28    attr_reader :thread
29
30    def self.catch(*args)
31      exc = new(*args)
32      exc.instance_variable_set(:@thread, Thread.current)
33      ::Kernel.catch(exc) {yield exc}
34    end
35
36    def exception(*)
37      # TODO: use Fiber.current to see if self can be thrown
38      if self.thread == Thread.current
39        bt = caller
40        begin
41          throw(self, bt)
42        rescue UncaughtThrowError
43        end
44      end
45      self
46    end
47  end
48
49  # :stopdoc:
50  THIS_FILE = /\A#{Regexp.quote(__FILE__)}:/o
51  CALLER_OFFSET = ((c = caller[0]) && THIS_FILE =~ c) ? 1 : 0
52  private_constant :THIS_FILE, :CALLER_OFFSET
53  # :startdoc:
54
55  # Perform an operation in a block, raising an error if it takes longer than
56  # +sec+ seconds to complete.
57  #
58  # +sec+:: Number of seconds to wait for the block to terminate. Any number
59  #         may be used, including Floats to specify fractional seconds. A
60  #         value of 0 or +nil+ will execute the block without any timeout.
61  # +klass+:: Exception Class to raise if the block fails to terminate
62  #           in +sec+ seconds.  Omitting will use the default, Timeout::Error
63  # +message+:: Error message to raise with Exception Class.
64  #             Omitting will use the default, "execution expired"
65  #
66  # Returns the result of the block *if* the block completed before
67  # +sec+ seconds, otherwise throws an exception, based on the value of +klass+.
68  #
69  # The exception thrown to terminate the given block cannot be rescued inside
70  # the block unless +klass+ is given explicitly.
71  #
72  # Note that this is both a method of module Timeout, so you can <tt>include
73  # Timeout</tt> into your classes so they have a #timeout method, as well as
74  # a module method, so you can call it directly as Timeout.timeout().
75  def timeout(sec, klass = nil, message = nil)   #:yield: +sec+
76    return yield(sec) if sec == nil or sec.zero?
77    message ||= "execution expired".freeze
78    from = "from #{caller_locations(1, 1)[0]}" if $DEBUG
79    e = Error
80    bl = proc do |exception|
81      begin
82        x = Thread.current
83        y = Thread.start {
84          Thread.current.name = from
85          begin
86            sleep sec
87          rescue => e
88            x.raise e
89          else
90            x.raise exception, message
91          end
92        }
93        return yield(sec)
94      ensure
95        if y
96          y.kill
97          y.join # make sure y is dead.
98        end
99      end
100    end
101    if klass
102      begin
103        bl.call(klass)
104      rescue klass => e
105        bt = e.backtrace
106      end
107    else
108      bt = Error.catch(message, &bl)
109    end
110    level = -caller(CALLER_OFFSET).size-2
111    while THIS_FILE =~ bt[level]
112      bt.delete_at(level)
113    end
114    raise(e, message, bt)
115  end
116
117  module_function :timeout
118end
119
120def timeout(*args, &block)
121  warn "Object##{__method__} is deprecated, use Timeout.timeout instead.", uplevel: 1
122  Timeout.timeout(*args, &block)
123end
124
125# Another name for Timeout::Error, defined for backwards compatibility with
126# earlier versions of timeout.rb.
127TimeoutError = Timeout::Error
128class Object
129  deprecate_constant :TimeoutError
130end
131