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|
# frozen_string_literal: true
# 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
# The version
VERSION = "0.4.1"
# Internal error raised to when a timeout is triggered.
class ExitException < Exception
def exception(*) # :nodoc:
self
end
end
# Raised by Timeout.timeout when the block times out.
class Error < RuntimeError
def self.handle_timeout(message) # :nodoc:
exc = ExitException.new(message)
begin
yield exc
rescue ExitException => e
raise new(message) if exc.equal?(e)
raise
end
end
end
# :stopdoc:
CONDVAR = ConditionVariable.new
QUEUE = Queue.new
QUEUE_MUTEX = Mutex.new
TIMEOUT_THREAD_MUTEX = Mutex.new
@timeout_thread = nil
private_constant :CONDVAR, :QUEUE, :QUEUE_MUTEX, :TIMEOUT_THREAD_MUTEX
class Request
attr_reader :deadline
def initialize(thread, timeout, exception_class, message)
@thread = thread
@deadline = GET_TIME.call(Process::CLOCK_MONOTONIC) + timeout
@exception_class = exception_class
@message = message
@mutex = Mutex.new
@done = false # protected by @mutex
end
def done?
@mutex.synchronize do
@done
end
end
def expired?(now)
now >= @deadline
end
def interrupt
@mutex.synchronize do
unless @done
@thread.raise @exception_class, @message
@done = true
end
end
end
def finished
@mutex.synchronize do
@done = true
end
end
end
private_constant :Request
def self.create_timeout_thread
watcher = Thread.new do
requests = []
while true
until QUEUE.empty? and !requests.empty? # wait to have at least one request
req = QUEUE.pop
requests << req unless req.done?
end
closest_deadline = requests.min_by(&:deadline).deadline
now = 0.0
QUEUE_MUTEX.synchronize do
while (now = GET_TIME.call(Process::CLOCK_MONOTONIC)) < closest_deadline and QUEUE.empty?
CONDVAR.wait(QUEUE_MUTEX, closest_deadline - now)
end
end
requests.each do |req|
req.interrupt if req.expired?(now)
end
requests.reject!(&:done?)
end
end
ThreadGroup::Default.add(watcher) unless watcher.group.enclosed?
watcher.name = "Timeout stdlib thread"
watcher.thread_variable_set(:"\0__detached_thread__", true)
watcher
end
private_class_method :create_timeout_thread
def self.ensure_timeout_thread_created
unless @timeout_thread and @timeout_thread.alive?
TIMEOUT_THREAD_MUTEX.synchronize do
unless @timeout_thread and @timeout_thread.alive?
@timeout_thread = create_timeout_thread
end
end
end
end
# We keep a private reference so that time mocking libraries won't break
# Timeout.
GET_TIME = Process.method(:clock_gettime)
private_constant :GET_TIME
# :startdoc:
# 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 <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, 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
Error.handle_timeout(message, &perform)
end
end
module_function :timeout
end
|
