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194 lines
5.6 KiB
Ruby
194 lines
5.6 KiB
Ruby
# frozen_string_literal: true
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# Timeout long-running blocks
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#
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# == Synopsis
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#
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# require 'timeout'
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# status = Timeout::timeout(5) {
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# # Something that should be interrupted if it takes more than 5 seconds...
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# }
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#
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# == Description
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#
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# Timeout provides a way to auto-terminate a potentially long-running
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# operation if it hasn't finished in a fixed amount of time.
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#
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# Previous versions didn't use a module for namespacing, however
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# #timeout is provided for backwards compatibility. You
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# should prefer Timeout.timeout instead.
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#
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# == Copyright
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#
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# Copyright:: (C) 2000 Network Applied Communication Laboratory, Inc.
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# Copyright:: (C) 2000 Information-technology Promotion Agency, Japan
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module Timeout
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VERSION = "0.3.0"
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# Raised by Timeout.timeout when the block times out.
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class Error < RuntimeError
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attr_reader :thread
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def self.catch(*args)
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exc = new(*args)
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exc.instance_variable_set(:@thread, Thread.current)
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exc.instance_variable_set(:@catch_value, exc)
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::Kernel.catch(exc) {yield exc}
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end
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def exception(*)
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# TODO: use Fiber.current to see if self can be thrown
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if self.thread == Thread.current
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bt = caller
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begin
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throw(@catch_value, bt)
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rescue UncaughtThrowError
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end
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end
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super
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end
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end
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# :stopdoc:
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CONDVAR = ConditionVariable.new
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QUEUE = Queue.new
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QUEUE_MUTEX = Mutex.new
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TIMEOUT_THREAD_MUTEX = Mutex.new
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@timeout_thread = nil
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private_constant :CONDVAR, :QUEUE, :QUEUE_MUTEX, :TIMEOUT_THREAD_MUTEX
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class Request
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attr_reader :deadline
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def initialize(thread, timeout, exception_class, message)
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@thread = thread
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@deadline = Process.clock_gettime(Process::CLOCK_MONOTONIC) + timeout
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@exception_class = exception_class
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@message = message
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@mutex = Mutex.new
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@done = false # protected by @mutex
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end
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def done?
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@mutex.synchronize do
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@done
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end
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end
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def expired?(now)
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now >= @deadline
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end
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def interrupt
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@mutex.synchronize do
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unless @done
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@thread.raise @exception_class, @message
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@done = true
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end
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end
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end
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def finished
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@mutex.synchronize do
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@done = true
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end
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end
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end
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private_constant :Request
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def self.create_timeout_thread
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Thread.new do
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Thread.current.thread_variable_set(:"\0__detached_thread__", true)
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requests = []
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while true
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until QUEUE.empty? and !requests.empty? # wait to have at least one request
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req = QUEUE.pop
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requests << req unless req.done?
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end
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closest_deadline = requests.min_by(&:deadline).deadline
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now = 0.0
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QUEUE_MUTEX.synchronize do
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while (now = Process.clock_gettime(Process::CLOCK_MONOTONIC)) < closest_deadline and QUEUE.empty?
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CONDVAR.wait(QUEUE_MUTEX, closest_deadline - now)
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end
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end
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requests.each do |req|
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req.interrupt if req.expired?(now)
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end
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requests.reject!(&:done?)
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end
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end
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end
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private_class_method :create_timeout_thread
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def self.ensure_timeout_thread_created
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unless @timeout_thread and @timeout_thread.alive?
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TIMEOUT_THREAD_MUTEX.synchronize do
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unless @timeout_thread and @timeout_thread.alive?
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@timeout_thread = create_timeout_thread
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end
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end
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end
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end
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# :startdoc:
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# Perform an operation in a block, raising an error if it takes longer than
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# +sec+ seconds to complete.
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#
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# +sec+:: Number of seconds to wait for the block to terminate. Any number
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# may be used, including Floats to specify fractional seconds. A
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# value of 0 or +nil+ will execute the block without any timeout.
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# +klass+:: Exception Class to raise if the block fails to terminate
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# in +sec+ seconds. Omitting will use the default, Timeout::Error
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# +message+:: Error message to raise with Exception Class.
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# Omitting will use the default, "execution expired"
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#
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# Returns the result of the block *if* the block completed before
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# +sec+ seconds, otherwise throws an exception, based on the value of +klass+.
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#
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# The exception thrown to terminate the given block cannot be rescued inside
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# the block unless +klass+ is given explicitly. However, the block can use
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# ensure to prevent the handling of the exception. For that reason, this
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# method cannot be relied on to enforce timeouts for untrusted blocks.
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#
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# If a scheduler is defined, it will be used to handle the timeout by invoking
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# Scheduler#timeout_after.
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#
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# Note that this is both a method of module Timeout, so you can <tt>include
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# Timeout</tt> into your classes so they have a #timeout method, as well as
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# a module method, so you can call it directly as Timeout.timeout().
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def timeout(sec, klass = nil, message = nil, &block) #:yield: +sec+
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return yield(sec) if sec == nil or sec.zero?
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message ||= "execution expired"
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if Fiber.respond_to?(:current_scheduler) && (scheduler = Fiber.current_scheduler)&.respond_to?(:timeout_after)
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return scheduler.timeout_after(sec, klass || Error, message, &block)
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end
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Timeout.ensure_timeout_thread_created
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perform = Proc.new do |exc|
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request = Request.new(Thread.current, sec, exc, message)
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QUEUE_MUTEX.synchronize do
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QUEUE << request
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CONDVAR.signal
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end
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begin
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return yield(sec)
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ensure
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request.finished
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end
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end
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if klass
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perform.call(klass)
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else
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backtrace = Error.catch(&perform)
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raise Error, message, backtrace
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end
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end
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module_function :timeout
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end
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