HashedWheelTimer | HashedWheelTimer implemented in C # and .Net Standard

HashedWheelTimer is a C# library. HashedWheelTimer has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.

It is a timer based on George Varghese and Tony Lauck's paper, Hashed and Hierarchical Timing Wheels: data structures to efficiently implement a timer facility. The concept on the Timer Wheel is rather simple to understand: in order to keep track of events on given resolution, an array of linked lists (alternatively - sets or even arrays, YMMV) is preallocated. When event is scheduled, it's address is found by dividing deadline time t by resolution and wheel size. The registration is then assigned with rounds (how many times we should go around the wheel in order for the time period to be elapsed). For each scheduled resolution, a bucket is created. There are wheel size buckets, each one of which is holding Registrations. Timer is going through each bucket from the first until the next one, and decrements rounds for each registration. As soon as registration's rounds is reaching 0, the timeout is triggered. After that it is either rescheduled (with same offset and amount of rounds as initially) or removed from timer. Hashed Wheel is often called approximated timer, since it acts on the certain resolution, which allows it's optimisations. All the tasks scheduled for the timer period lower than the resolution or "between" resolution steps will be rounded to the "ceiling" (for example, given resolution 10 milliseconds, all the tasks for 5,6,7 etc milliseconds will first fire after 10, and 15, 16, 17 will first trigger after 20). If you're a visual person, it might be useful for you to check out these slides, which help to understand the concept underlying the Hashed Wheel Timer better.