Prevent fiber switching in tick function and signal handlers

[trowski]

Switching fibers in these contexts causes unexpected consequences:

• Switching during a tick will prevent further ticks from being executed until the fiber is resumed.
• Switching when handing a signal will prevent further signals being handled until the fiber is resumed.

This PR prevents fiber switching in either context. It is possible in the future ticks or signal handling may be modified to be re-entrant, allowing multiple fibers to enter the handler function. Preventing fiber switching gives us greater freedom to define switching behavior in the future should we decide to properly support switching fibers. However, it is my opinion that support for fiber switching is not really necessary in these contexts.

[cmb69]

Thank you!

However, it is my opinion that support for fiber switching is not really necessary in these contexts.

I concur.

[Alimadadi]

So, please update the docs too. I have a suggestion:

Fiber::suspend
(PHP 8 >= 8.1.0)
Fiber::suspend — Suspends execution of the current fiber (Well, except if you use it inside of tick functions, because we are too good to leave even a harmless bug open, but also too unwilling to fix issues of features that we don't like enough).

That's sad, really sad.

[staabm]

@Alimadadi feel free to invest your own free time to investigate the bug (or your own money to contract someone doing it for you) and propose a proper solution - instead of judging about other people, investing their own free time to investigate your bugs.

it seems as of now, you are the only one having a use-case for fibers and tick functions in combination.

[Alimadadi]

@staabm No judge here at all.
What I mean by saying "it's sad", was about not being able to use those features in future inside pure PHP, even if it's buggy.
I think I can continue to use other libraries for my purpose, or comment out a couple of lines before compiling PHP.
And yes, it's open source software, and we are all very thankful of all programmers who share their time for contributing and making a better world 💐.
Maybe I do what you said in future and contribute too.
Peace.