Simple implementation of Promises A+ for our sync case (using queue)

This commit is contained in:
vladar 2016-12-02 18:43:54 +07:00
parent 821e96508b
commit 3a375bb78e
2 changed files with 455 additions and 0 deletions

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<?php
namespace GraphQL\Executor\Promise\Adapter;
use GraphQL\Utils;
/**
* Class SyncPromise
*
* Simplistic (yet full-featured) implementation of Promises A+ spec for regular PHP `sync` mode
* (using queue to defer promises execution)
*
* @package GraphQL\Executor\Promise\Adapter
*/
class SyncPromise
{
const PENDING = 'pending';
const FULFILLED = 'fulfilled';
const REJECTED = 'rejected';
/**
* @var \SplQueue
*/
public static $queue;
public static function runQueue()
{
while (self::$queue && !self::$queue->isEmpty()) {
$task = self::$queue->dequeue();
$task();
}
}
public $state = self::PENDING;
private $result;
/**
* Promises created in `then` method of this promise and awaiting for resolution of this promise
* @var array
*/
private $waiting = [];
public function __construct()
{
if (!self::$queue) {
self::$queue = new \SplQueue();
}
}
public function reject(\Exception $reason)
{
switch ($this->state) {
case self::PENDING:
$this->state = self::REJECTED;
$this->result = $reason;
$this->enqueueWaitingPromises();
break;
case self::REJECTED:
if ($reason !== $this->result) {
throw new \Exception("Cannot change rejection reason");
}
break;
case self::FULFILLED:
throw new \Exception("Cannot reject fulfilled promise");
}
return $this;
}
public function resolve($value)
{
switch ($this->state) {
case self::PENDING:
if ($value === $this) {
throw new \Exception("Cannot resolve promise with self");
}
if ($value instanceof self) {
$value->then(
function($resolvedValue) {
$this->resolve($resolvedValue);
},
function($reason) {
$this->reject($reason);
}
);
return $this;
}
$this->state = self::FULFILLED;
$this->result = $value;
$this->enqueueWaitingPromises();
break;
case self::FULFILLED:
if ($this->result !== $value) {
throw new \Exception("Cannot change value of fulfilled promise");
}
break;
case self::REJECTED:
throw new \Exception("Cannot resolve rejected promise");
}
return $this;
}
public function then(callable $onFulfilled = null, callable $onRejected = null)
{
if ($this->state === self::REJECTED && !$onRejected) {
return $this;
}
if ($this->state === self::FULFILLED && !$onFulfilled) {
return $this;
}
$tmp = new self();
$this->waiting[] = [$tmp, $onFulfilled, $onRejected];
if ($this->state !== self::PENDING) {
$this->enqueueWaitingPromises();
}
return $tmp;
}
private function enqueueWaitingPromises()
{
Utils::invariant($this->state !== self::PENDING, 'Cannot enqueue derived promises when parent is still pending');
foreach ($this->waiting as $descriptor) {
self::$queue->enqueue(function () use ($descriptor) {
/** @var $promise self */
list($promise, $onFulfilled, $onRejected) = $descriptor;
if ($this->state === self::FULFILLED) {
try {
$promise->resolve($onFulfilled ? $onFulfilled($this->result) : $this->result);
} catch (\Exception $e) {
$promise->reject($e);
}
} else if ($this->state === self::REJECTED) {
try {
$promise->resolve($onRejected ? $onRejected($this->result) : $this->result);
} catch (\Exception $e) {
$promise->reject($e);
}
}
});
}
$this->waiting = [];
}
}

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<?php
namespace GraphQL\Tests\Executor\Promise;
use GraphQL\Executor\Promise\Adapter\SyncPromise;
class SyncPromiseTest extends \PHPUnit_Framework_TestCase
{
public function getFulfilledPromiseResolveData()
{
$onFulfilledReturnsNull = function() {
return null;
};
$onFulfilledReturnsSameValue = function($value) {
return $value;
};
$onFulfilledReturnsOtherValue = function($value) {
return 'other-' . $value;
};
$onFulfilledThrows = function($value) {
throw new \Exception("onFulfilled throws this!");
};
return [
// $resolvedValue, $onFulfilled, $expectedNextValue, $expectedNextReason, $expectedNextState
['test-value', null, 'test-value', null, SyncPromise::FULFILLED],
[uniqid(), $onFulfilledReturnsNull, null, null, SyncPromise::FULFILLED],
['test-value', $onFulfilledReturnsSameValue, 'test-value', null, SyncPromise::FULFILLED],
['test-value-2', $onFulfilledReturnsOtherValue, 'other-test-value-2', null, SyncPromise::FULFILLED],
['test-value-3', $onFulfilledThrows, null, "onFulfilled throws this!", SyncPromise::REJECTED],
];
}
/**
* @dataProvider getFulfilledPromiseResolveData
*/
public function testFulfilledPromise(
$resolvedValue,
$onFulfilled,
$expectedNextValue,
$expectedNextReason,
$expectedNextState
)
{
$promise = new SyncPromise();
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$promise->resolve($resolvedValue);
$this->assertEquals(SyncPromise::FULFILLED, $promise->state);
try {
$promise->resolve($resolvedValue . '-other-value');
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals('Cannot change value of fulfilled promise', $e->getMessage());
}
try {
$promise->reject(new \Exception('anything'));
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals('Cannot reject fulfilled promise', $e->getMessage());
}
$nextPromise = $promise->then(null, function() {});
$this->assertSame($promise, $nextPromise);
$onRejectedCalled = false;
$nextPromise = $promise->then($onFulfilled, function () use (&$onRejectedCalled) {
$onRejectedCalled = true;
});
if ($onFulfilled) {
$this->assertNotSame($promise, $nextPromise);
$this->assertEquals(SyncPromise::PENDING, $nextPromise->state);
} else {
$this->assertEquals(SyncPromise::FULFILLED, $nextPromise->state);
}
$this->assertEquals(false, $onRejectedCalled);
$this->assertValidPromise($nextPromise, $expectedNextReason, $expectedNextValue, $expectedNextState);
$nextPromise2 = $promise->then($onFulfilled);
$nextPromise3 = $promise->then($onFulfilled);
if ($onFulfilled) {
$this->assertNotSame($nextPromise, $nextPromise2);
}
SyncPromise::runQueue();
$this->assertValidPromise($nextPromise2, $expectedNextReason, $expectedNextValue, $expectedNextState);
$this->assertValidPromise($nextPromise3, $expectedNextReason, $expectedNextValue, $expectedNextState);
}
public function getRejectedPromiseData()
{
$onRejectedReturnsNull = function() {
return null;
};
$onRejectedReturnsSomeValue = function($reason) {
return 'some-value';
};
$onRejectedThrowsSameReason = function($reason) {
throw $reason;
};
$onRejectedThrowsOtherReason = function($value) {
throw new \Exception("onRejected throws other!");
};
return [
// $rejectedReason, $onRejected, $expectedNextValue, $expectedNextReason, $expectedNextState
[new \Exception('test-reason'), null, null, 'test-reason', SyncPromise::REJECTED],
[new \Exception('test-reason-2'), $onRejectedReturnsNull, null, null, SyncPromise::FULFILLED],
[new \Exception('test-reason-3'), $onRejectedReturnsSomeValue, 'some-value', null, SyncPromise::FULFILLED],
[new \Exception('test-reason-4'), $onRejectedThrowsSameReason, null, 'test-reason-4', SyncPromise::REJECTED],
[new \Exception('test-reason-5'), $onRejectedThrowsOtherReason, null, 'onRejected throws other!', SyncPromise::REJECTED],
];
}
/**
* @dataProvider getRejectedPromiseData
*/
public function testRejectedPromise(
$rejectedReason,
$onRejected,
$expectedNextValue,
$expectedNextReason,
$expectedNextState
)
{
$promise = new SyncPromise();
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$promise->reject($rejectedReason);
$this->assertEquals(SyncPromise::REJECTED, $promise->state);
try {
$promise->reject(new \Exception('other-reason'));
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals('Cannot change rejection reason', $e->getMessage());
}
try {
$promise->resolve('anything');
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals('Cannot resolve rejected promise', $e->getMessage());
}
$nextPromise = $promise->then(function() {}, null);
$this->assertSame($promise, $nextPromise);
$onFulfilledCalled = false;
$nextPromise = $promise->then(
function () use (&$onFulfilledCalled) {
$onFulfilledCalled = true;
},
$onRejected
);
if ($onRejected) {
$this->assertNotSame($promise, $nextPromise);
$this->assertEquals(SyncPromise::PENDING, $nextPromise->state);
} else {
$this->assertEquals(SyncPromise::REJECTED, $nextPromise->state);
}
$this->assertEquals(false, $onFulfilledCalled);
$this->assertValidPromise($nextPromise, $expectedNextReason, $expectedNextValue, $expectedNextState);
$nextPromise2 = $promise->then(null, $onRejected);
$nextPromise3 = $promise->then(null, $onRejected);
if ($onRejected) {
$this->assertNotSame($nextPromise, $nextPromise2);
}
SyncPromise::runQueue();
$this->assertValidPromise($nextPromise2, $expectedNextReason, $expectedNextValue, $expectedNextState);
$this->assertValidPromise($nextPromise3, $expectedNextReason, $expectedNextValue, $expectedNextState);
}
public function testPendingPromise()
{
$promise = new SyncPromise();
$this->assertEquals(SyncPromise::PENDING, $promise->state);
try {
$promise->resolve($promise);
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals('Cannot resolve promise with self', $e->getMessage());
$this->assertEquals(SyncPromise::PENDING, $promise->state);
}
// Try to resolve with other promise (must resolve when other promise resolves)
$otherPromise = new SyncPromise();
$promise->resolve($otherPromise);
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$this->assertEquals(SyncPromise::PENDING, $otherPromise->state);
$otherPromise->resolve('the value');
$this->assertEquals(SyncPromise::FULFILLED, $otherPromise->state);
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$this->assertValidPromise($promise, null, 'the value', SyncPromise::FULFILLED);
$promise = new SyncPromise();
$promise->resolve('resolved!');
$this->assertValidPromise($promise, null, 'resolved!', SyncPromise::FULFILLED);
// Test rejections
$promise = new SyncPromise();
$this->assertEquals(SyncPromise::PENDING, $promise->state);
try {
$promise->reject('a');
$this->fail('Expected exception not thrown');
} catch (\Exception $e) {
$this->assertEquals(SyncPromise::PENDING, $promise->state);
}
$promise->reject(new \Exception("Rejected Reason"));
$this->assertValidPromise($promise, "Rejected Reason", null, SyncPromise::REJECTED);
}
public function testPendingPromiseThen()
{
$promise = new SyncPromise();
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$nextPromise = $promise->then();
$this->assertNotSame($promise, $nextPromise);
$this->assertEquals(SyncPromise::PENDING, $promise->state);
$this->assertEquals(SyncPromise::PENDING, $nextPromise->state);
// Make sure that it queues derivative promises until resolution:
$onFulfilledCount = 0;
$onRejectedCount = 0;
$onFulfilled = function($value) use (&$onFulfilledCount) {
$onFulfilledCount++;
return $onFulfilledCount;
};
$onRejected = function($reason) use (&$onRejectedCount) {
$onRejectedCount++;
throw $reason;
};
$nextPromise2 = $promise->then($onFulfilled, $onRejected);
$nextPromise3 = $promise->then($onFulfilled, $onRejected);
$nextPromise4 = $promise->then($onFulfilled, $onRejected);
$this->assertEquals(SyncPromise::$queue->count(), 0);
$this->assertEquals($onFulfilledCount, 0);
$this->assertEquals($onRejectedCount, 0);
$promise->resolve(1);
$this->assertEquals(SyncPromise::$queue->count(), 4);
$this->assertEquals($onFulfilledCount, 0);
$this->assertEquals($onRejectedCount, 0);
$this->assertEquals(SyncPromise::PENDING, $nextPromise->state);
$this->assertEquals(SyncPromise::PENDING, $nextPromise2->state);
$this->assertEquals(SyncPromise::PENDING, $nextPromise3->state);
$this->assertEquals(SyncPromise::PENDING, $nextPromise4->state);
SyncPromise::runQueue();
$this->assertEquals(SyncPromise::$queue->count(), 0);
$this->assertEquals($onFulfilledCount, 3);
$this->assertEquals($onRejectedCount, 0);
$this->assertValidPromise($nextPromise, null, 1, SyncPromise::FULFILLED);
$this->assertValidPromise($nextPromise2, null, 1, SyncPromise::FULFILLED);
$this->assertValidPromise($nextPromise3, null, 2, SyncPromise::FULFILLED);
$this->assertValidPromise($nextPromise4, null, 3, SyncPromise::FULFILLED);
}
private function assertValidPromise(SyncPromise $promise, $expectedNextReason, $expectedNextValue, $expectedNextState)
{
$actualNextValue = null;
$actualNextReason = null;
$onFulfilledCalled = false;
$onRejectedCalled = false;
$promise->then(
function($nextValue) use (&$actualNextValue, &$onFulfilledCalled) {
$onFulfilledCalled = true;
$actualNextValue = $nextValue;
},
function(\Exception $reason) use (&$actualNextReason, &$onRejectedCalled) {
$onRejectedCalled = true;
$actualNextReason = $reason->getMessage();
}
);
$this->assertEquals($onFulfilledCalled, false);
$this->assertEquals($onRejectedCalled, false);
SyncPromise::runQueue();
$this->assertEquals(!$expectedNextReason, $onFulfilledCalled);
$this->assertEquals(!!$expectedNextReason, $onRejectedCalled);
$this->assertEquals($expectedNextValue, $actualNextValue);
$this->assertEquals($expectedNextReason, $actualNextReason);
$this->assertEquals($expectedNextState, $promise->state);
}
}