This is better for performance because these then don't need to be reevaluated every time they are called.
When encountering an unqualified function or constant reference, PHP will first try to locate a symbol in the current namespace by that name, and then fall back to the global namespace.
This short-circuits the check, which has substantial performance effects in some cases - in particular, ord(), chr() and strlen() show ~1500x faster calls when they are fully qualified.
However, this doesn't mean that PM is getting a massive amount faster. In real world terms, this translates to about 10-15% performance improvement.
But before anyone gets excited, you should know that the CodeOptimizer in the PreProcessor repo has been applying fully-qualified symbol optimizations to Jenkins builds for years, which is one of the reasons why Jenkins builds have better performance than home-built or source installations.
We're choosing to do this for the sake of future SafePHP integration and also to be able to get rid of the buggy CodeOptimizer, so that phar and source are more consistent.
This cleans up some cargo-cult code poorly copied from Bukkit, which has negative performance effects and also makes internal event handling more complex than necessary.
## API changes
- Removed `EventExecutor` and `MethodEventExecutor`.
- A listener is no longer required for an event handler to be registered. Closure objects can now be used directly provided that they meet the conditions for registration.
- `PluginManager->registerEvent()` signature has changed: the `Listener` and `EventExecutor` parameters have been removed and a `\Closure $handler` has been added in its place.
- `RegisteredListener` now requires a `Closure` parameter instead of `Listener, EventExecutor`.
## Behavioural changes
These changes reduce the execution complexity involved with calling an event handler. Since event calls can happen in hot paths, this may have visible positive effects on performance.
Initial testing reveals a performance improvement of ~15% per event handler call compared to the old method.
* Event handlers always handle subclass events. public static $handlerList no longer required.
* Removed $handlerList declarations
* HandlerList cleanup: Removed HandlerList->handlers and related bake methods
* Removed obsolete Event->getHandlers()
* EventPriority: Added fromString()
* PluginManager: throw exceptions on registering handlers with invalid priorities
This allows specifying a handler of `EntityDamageEvent` which will handle any instanceof it (as per current behaviour), AND also now allows specifying a handler specifically for `EntityDamageByEntityEvent`, which only handles `EntityDamageEvent`.
This was not previously possible due to limitations in the way handlers were registered.
Abstract events may not be handled unless they declare the `@allowHandle` PhpDoc tag.
