Permit overriding join() to intercept thread shutdowns triggered by pthreads itself

[dktapps]

Environment

• PHP: 7.2.13
• pthreads: 5eb80c0c691aa81e0d235bdd37f6f30b633c433e
• OS: w10 x64

Summary

I would like to be able to have my custom join() function called when the thread context tries to be destroyed. Currently this isn't possible because pthreads_join is called directly, without giving the user chance to react to it.

Reproducing Code

$t = new class extends \Thread{

	private $shutdown = false;

	public function run(){
		$this->synchronized(function(){
			while(!$this->shutdown){
				$this->wait();
			}
		});
	}

	public function join(){
		$this->synchronized(function(){
			$this->shutdown = true;
			$this->notify();
		});
	}
};

$t->start();
unset($t);
die("OK");

Desired output

OK

Actual Output

Nothing - the script just hangs at the unset() call as pthreads tries to fruitlessly join it.