Event system

[kyle-emmerich]

There is an experimental class under Experiments/EventStream that can store event objects for another system to read. Right now, it supports basic synchronization in that it can only read OR write; not both.

Features:

• [x] Circular buffer for storing events
• [x] Basic synchronization
• [ ] Filtered delegates
• [ ] Simultaneous read/write
• [ ] Dynamic heuristic-driven buffer sizing

Since this will be a very core concept for Blueshift, it needs to be very fast and must avoid cache misses when possible. Much of this is dependent on user code though; slow event processing will lead to a lot of thread preemption by the operating system and will thrash the cache.

[kyle-emmerich]

Also need to think about how this will interact with Lua. The Lua API needs to be able to recreate the delegate system. Perhaps multiple event queues can be used, and events not handled by C++ may be left in another queue for Lua to handle.

On second thought, maybe no delegate system on the C++ side. The system processing events should be able to handle delegation as it sees fit.

[kyle-emmerich]

One last thing: some examples should be written up for using an event queue. Should help guide the creation of its API if some use-cases are known.