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[3.x] Fast forward resolved/rejected promises with await #22

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[3.x] Fast forward resolved/rejected promises with await #22

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61 changes: 45 additions & 16 deletions src/functions.php
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Original file line number Diff line number Diff line change
Expand Up @@ -53,18 +53,47 @@
function await(PromiseInterface $promise)
{
$wait = true;
$resolved = null;
$exception = null;
$resolved = false;
$rejected = false;
$resolvedValue = null;
$rejectedThrowable = null;

$promise->then(
function ($c) use (&$resolved, &$wait) {
$resolved = $c;
function ($c) use (&$resolved, &$resolvedValue, &$wait) {
$resolvedValue = $c;
$resolved = true;
$wait = false;
Loop::stop();
},
function ($error) use (&$exception, &$rejected, &$wait) {
$exception = $error;
function ($error) use (&$rejected, &$rejectedThrowable, &$wait) {
// promise is rejected with an unexpected value (Promise API v1 or v2 only)
if (!$error instanceof \Exception && !$error instanceof \Throwable) {
$error = new \UnexpectedValueException(
'Promise rejected with unexpected value of type ' . (is_object($error) ? get_class($error) : gettype($error))
);

// avoid garbage references by replacing all closures in call stack.
// what a lovely piece of code!
$r = new \ReflectionProperty('Exception', 'trace');
$r->setAccessible(true);
$trace = $r->getValue($error);

// Exception trace arguments only available when zend.exception_ignore_args is not set
// @codeCoverageIgnoreStart
foreach ($trace as $ti => $one) {
if (isset($one['args'])) {
foreach ($one['args'] as $ai => $arg) {
if ($arg instanceof \Closure) {
$trace[$ti]['args'][$ai] = 'Object(' . \get_class($arg) . ')';
}
}
}
}
// @codeCoverageIgnoreEnd
$r->setValue($error, $trace);
}

$rejectedThrowable = $error;
$rejected = true;
$wait = false;
Loop::stop();
Expand All @@ -75,25 +104,25 @@ function ($error) use (&$exception, &$rejected, &$wait) {
// argument does not show up in the stack trace in PHP 7+ only.
$promise = null;

if ($rejected) {
throw $rejectedThrowable;
}

if ($resolved) {
return $resolvedValue;
}

while ($wait) {
Loop::run();
}

if ($rejected) {
// promise is rejected with an unexpected value (Promise API v1 or v2 only)
if (!$exception instanceof \Throwable) {
$exception = new \UnexpectedValueException(
'Promise rejected with unexpected value of type ' . (is_object($exception) ? get_class($exception) : gettype($exception))
);
}

throw $exception;
throw $rejectedThrowable;
}

return $resolved;
return $resolvedValue;
}


/**
* Execute a Generator-based coroutine to "await" promises.
*
Expand Down
32 changes: 32 additions & 0 deletions tests/AwaitTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,38 @@ public function testAwaitShouldNotCreateAnyGarbageReferencesForRejectedPromise()
$this->assertEquals(0, gc_collect_cycles());
}

public function testAlreadyFulfilledPromiseShouldShortCircuitAndNotRunLoop()
{
for ($i = 0; $i < 6; $i++) {
$this->assertSame($i, React\Async\await(React\Promise\resolve($i)));
}
}

public function testPendingPromiseShouldNotShortCircuitAndRunLoop()
{
Loop::futureTick($this->expectCallableOnce());

$this->assertSame(1, React\Async\await(new Promise(static function (callable $resolve) {
Loop::futureTick(static function () use ($resolve) {
$resolve(1);
});
})));
}

public function testPendingPromiseShouldNotShortCircuitAndRunLoopAndThrowOnRejection()
{
Loop::futureTick($this->expectCallableOnce());

$this->expectException(\Exception::class);
$this->expectExceptionMessage('test');

$this->assertSame(1, React\Async\await(new Promise(static function (callable $resolve, callable $reject) {
Loop::futureTick(static function () use ($reject) {
$reject(new \Exception('test'));
});
})));
}

public function testAwaitShouldNotCreateAnyGarbageReferencesForPromiseRejectedWithNullValue()
{
if (!interface_exists('React\Promise\CancellablePromiseInterface')) {
Expand Down