ExecutionDeadline
Odds are, you should never ever, ever, use Ruby's built in timeout module unless you are 100% certain the wrapped code may be interrupted at any point. This gem provides a way to easily identify safe breakpoints for timeout operations.
Usage of this gem should be combined with the-ultimate-guide-to-ruby-timeouts to ensure your application releases resources from otherwise stuck threads.
Why use deadlines?
Installation
Add this line to your application's Gemfile:
gem 'execution_deadline'
And then execute:
$ bundle
Or install it yourself as:
$ gem install execution_deadline
Usage
Deadline Enforcement
Deadlines are enforced only at breakpoints in the code specifically marked as safe to error. This is most easily done with the simple method wrappers provided in ExecutionDeadline::Helpers.
Examples
class SlowClass
extend ExecutionDeadline::Helpers
deadline in: 1
def perform
sub_method_1
sub_method_1
method_never_called
end
deadline runs_for: 0.6
def sub_method_1
sleep 0.7
end
def method_never_called; end
end
instance = SlowClass.new
instance.perform # Throws OutOfTime error since sub_method_1 takes 0.6s of
# the total allowed 1s execution time. Since only 0.4s
# is left, the second execution of sub_method_1 is prevented
When calculating time left after the execution of a method the actual execution time of the method is used. Consider the above example, but with a shorter actual execution time.
class ThinksItsSlowClass
extend ExecutionDeadline::Helpers
deadline in: 1
def perform
sub_method_1
sub_method_1
method_never_called
end
deadline runs_for: 0.6
def sub_method_1
sleep 0.1
end
def method_is_called
:abcd
end
end
instance = SlowClass.new
instance.perform # No errors are thrown and :abcd returned. Even though
# sub_method_1 says it will take 0.6 seconds, it actually
# takes 0.1 seconds. The second execution of sub_method_1 is
# checked against the remaining 0.9s, and allowed to continue
Deadlines are also usable on class methods and module methods.
class SlowClass
extend ExecutionDeadline::Helpers
deadline in: 1
def self.perform
sub_method_1
sub_method_1
method_never_called
end
deadline runs_for: 0.6
def self.sub_method_1
sleep 0.7
end
def self.method_never_called; end
end
SlowClass..perform # Throws OutOfTime error
module SlowModule
extend ExecutionDeadline::Helpers
deadline in: 1
def self.perform
sub_method_1
sub_method_1
method_never_called
end
deadline runs_for: 0.6
def self.sub_method_1
sleep 0.7
end
def self.method_never_called; end
end
SlowModule.perform # Throws OutOfTime error
Raised Errors
ExecutionDeadline::OutOfTime
- Raised when a deadlined method is called but
there is less time left then the expected runtime.
ExecutionDeadline::DeadlineExceeded
- Raised when a deadlined method is
and completed after the deadline time has passed.
All errors are subclasses of ExecutionDeadline::DeadlineError
Customizing Errors
The errors raised may be customized using the raises
keyword. The error to be
raised may only be set when the deadline is defined (using the in
keyword)
module SlowModule
class CustomError < StandardError; end
extend ExecutionDeadline::Helpers
deadline in: 1, raises: CustomError
def self.runs_out_of_time
sub_method_1
sub_method_1
method_never_called
end
deadline runs_for: 0.6
def self.sub_method_1
sleep 0.8
end
deadline in: 1, raises: CustomError
def self.runs_over_time
runs_over
method_never_called
end
deadline runs_for: 0.5
def self.runs_over
sleep 1.1
end
def self.method_never_called; end
end
SlowModule.runs_out_of_time # Throws CustomError error in place of OutOfTime
SlowModule.runs_over_time # Throws CustomError error in place of DeadlineExceeded
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run rake spec
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/execution_deadline. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
License
The gem is available as open source under the terms of the MIT License.
Code of Conduct
Everyone interacting in the ExecutionDeadline project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.