add example for timingwheel

[tsingson]

add example

[RussellLuo]

@tsingson Thanks for your contribution! The example code you provide is correct and well-formatted, but I think it's a little complicated.

While using the same library (here is timingwheel), different users have different use-cases and different opinions about how to structure their code. For simplicity, I think the examples of timingwheel should try to avoid:

• involving use-case specific things
  • in your example code, like periodically printing out the current time from goInternalTimer(), or continuously printing out the current time in for i := 1; i <= MainGoroutineWait; i++ loop.
• or showing two many structuring styles
  • in your example code, like defining three global variables tw, taskChannel and tl, and initializing them within init(), or defining many small functions such as timingwheelTaskTriggerFunc(), timingWheelTaskRunner(), goInternalTimerTaskRunner() and goInternalTimer().

In other words, being a basic library, timingwheel should provide examples as concentrated (also simple) as possible, just like what most standard Go libraries do.

So if I understand your example code correctly, the core snippet that is concentrated on how to use timingwheel is mostly the same with the first example (i.e. Example (AddTimer)) provided in Godoc?

[RussellLuo]

The API to create a new timer has been changed (by this commit), see Godoc for new examples.

I hope the new API will be considered more user-friendly.

[tsingson]

Thank you for your quick response.

Yes, my example is a bit complicated and not easy to understand. Perhaps this is related to personal coding habits.