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Register shutdown function to clear event loop #101

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Register shutdown function to clear event loop #101

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bc4cfa6
Register shutdown function to clear event loop
trowski Dec 7, 2024
1f1e9be
Collect GC cycles first
trowski Dec 7, 2024
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36 changes: 36 additions & 0 deletions examples/shutdown.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
<?php

declare(strict_types=1);

require __DIR__ . '/../vendor/autoload.php';

use Revolt\EventLoop;

\register_shutdown_function(function (): void {
\register_shutdown_function(function (): void {
EventLoop::defer(function (): void {
print 'Shutdown function registered within pre-loop-run shutdown function' . PHP_EOL;
});
});


EventLoop::defer(function (): void {
print 'Shutdown function registered before EventLoop::run()' . PHP_EOL;
});
});

EventLoop::run();

\register_shutdown_function(function (): void {
\register_shutdown_function(function (): void {
EventLoop::defer(function (): void {
print 'Shutdown function registered within post-loop-run shutdown function' . PHP_EOL;
});
});

EventLoop::defer(function (): void {
print 'Shutdown function registered after EventLoop::run()' . PHP_EOL;
});
});

print 'End of script' . PHP_EOL;
31 changes: 29 additions & 2 deletions src/EventLoop.php
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,12 @@ final class EventLoop
public static function setDriver(Driver $driver): void
{
/** @psalm-suppress RedundantPropertyInitializationCheck, RedundantCondition */
if (isset(self::$driver) && self::$driver->isRunning()) {
throw new \Error("Can't swap the event loop driver while the driver is running");
if (isset(self::$driver)) {
if (self::$driver->isRunning()) {
throw new \Error("Can't swap the event loop driver while the driver is running");
}
} else {
\register_shutdown_function(self::onShutdown(...), 0);
}

try {
Expand Down Expand Up @@ -67,6 +71,29 @@ protected function now(): float
}
}

private static function onShutdown(int $invocationCount): void
{
\gc_collect_cycles();

$driver = self::getDriver();

$pending = false;
foreach ($driver->getIdentifiers() as $identifier) {
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Shouldn't this also check for pending microtasks/queued callbacks?

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@trowski trowski Dec 7, 2024 •
edited
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Yes, you're right. I guess AbstractDriver::isEmpty() also isn't doing that and maybe should (though that function is private and due to how the queue is invoked, I'm not sure there ever can be queued microtasks when isEmpty() is called).

Unfortunately there is nothing on Driver which will let me query if there are queued microtasks, so that would need to be added.

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In my code, I just unconditionally do

                if (!EventLoop::getDriver()->isRunning()) {
                        $delay = PHP_SAPI === 'cli' ? 5 : 1;
                        $id2 = null;
                        EventLoop::unreference($id1 = EventLoop::delay((float)$delay, static function () use ($delay, &$id2): void {
                                $t = time() - $delay;
                                EventLoop::unreference($id2 = EventLoop::repeat(1.0, static function () use ($t): void {
                                        $t = time() - $t;
                                        Logger::get()->error("Still waiting for shutdown of the event loop for {$t} seconds...");
                                }));
                        }));
                        EventLoop::run();
                        EventLoop::cancel($id1);
                        if ($id2 !== null) {
                                EventLoop::cancel($id2);
                        }
                }

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i.e. an unconditional run()

if ($driver->isEnabled($identifier) && $driver->isReferenced($identifier)) {
$pending = true;
break;
}
}

if ($pending) {
$driver->run();
}

if (!$invocationCount++ || $pending) {
\register_shutdown_function(self::onShutdown(...), $invocationCount);
}
}

/**
* Queue a microtask.
*
Expand Down
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