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Allow GC of arguments during microtask execution #60

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Merged
trowski merged 1 commit into from
Aug 1, 2022
Merged

Allow GC of arguments during microtask execution #60

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3 changes: 2 additions & 1 deletion src/EventLoop/Internal/AbstractDriver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -418,7 +418,8 @@ private function invokeMicrotasks(): void
[$callback, $args] = $this->microtaskQueue->dequeue();

try {
$callback(...$args);
// Clear $args to allow garbage collection
$callback(...$args, ...($args = []));
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@WyriHaximus WyriHaximus Jul 31, 2022

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So how does this work? You first pass all the elements of the $args array into the argument list for $callback, and then you overwrite $args with an empty array and also "push" that to the same argument list?

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@Nevay Nevay Jul 31, 2022

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Yes, it overwrites the $args array (and pushes zero arguments to the argument list) after pushing the original arguments and before invoking the callback.

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@WyriHaximus WyriHaximus Aug 1, 2022

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Near trick, it's a tad confusing when you first read the line tbh.

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@HLeithner HLeithner Aug 1, 2022

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A better documentation what happens here would be good especially for people like me that doesn't see what's happening at the first glance and why it's needed.

} catch (\Throwable $exception) {
$this->error($callback, $exception);
} finally {
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18 changes: 18 additions & 0 deletions test/Driver/DriverTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1387,6 +1387,24 @@ public function testMicrotaskExecutedImmediatelyAfterCallback(): void
});
}

public function testMicrotaskExecutionDoesNotKeepReferenceToArgs(): void
{
$this->expectOutputString('123');

$this->loop->queue(function (object $object): void {
print 1;
unset($object);
print 3;
}, new class () {
public function __destruct()
{
print 2;
}
});

$this->loop->run();
}

public function testMicrotaskThrowingStillExecutesNextMicrotask(): void
{
$exception = new \Exception();
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