From e97ca7f971662de1973c67e7f04c56f68a6d330f Mon Sep 17 00:00:00 2001
From: vladar <vladimir.razuvaev@gmail.com>
Date: Sat, 3 Dec 2016 02:14:14 +0700
Subject: [PATCH] Execution: added SyncPromiseAdapter and made it default for
 Executor (+removed GenericPromiseAdapter)

---
 src/Deferred.php                              |  53 +++++
 src/Executor/Executor.php                     |   8 +-
 .../Promise/Adapter/GenericPromiseAdapter.php |  57 -----
 src/Executor/Promise/Adapter/SyncPromise.php  |  21 +-
 .../Promise/Adapter/SyncPromiseAdapter.php    | 146 +++++++++++++
 src/Utils.php                                 |   3 +
 .../Promise/SyncPromiseAdapterTest.php        | 203 ++++++++++++++++++
 tests/Executor/Promise/SyncPromiseTest.php    |   6 +-
 8 files changed, 424 insertions(+), 73 deletions(-)
 create mode 100644 src/Deferred.php
 delete mode 100644 src/Executor/Promise/Adapter/GenericPromiseAdapter.php
 create mode 100644 src/Executor/Promise/Adapter/SyncPromiseAdapter.php
 create mode 100644 tests/Executor/Promise/SyncPromiseAdapterTest.php

diff --git a/src/Deferred.php b/src/Deferred.php
new file mode 100644
index 0000000..2fc6c1d
--- /dev/null
+++ b/src/Deferred.php
@@ -0,0 +1,53 @@
+<?php
+namespace GraphQL;
+
+use GraphQL\Executor\Promise\Adapter\SyncPromise;
+
+class Deferred
+{
+    private static $queue;
+
+    private $callback;
+
+    /**
+     * @var SyncPromise
+     */
+    public $promise;
+
+    public static function getQueue()
+    {
+        return self::$queue ?: self::$queue = new \SplQueue();
+    }
+
+    public static function runQueue()
+    {
+        $q = self::getQueue();
+        while (!$q->isEmpty()) {
+            /** @var self $dfd */
+            $dfd = $q->dequeue();
+            $dfd->run();
+        }
+    }
+
+    public function __construct(callable $callback)
+    {
+        $this->callback = $callback;
+        $this->promise = new SyncPromise();
+        self::getQueue()->enqueue($this);
+    }
+
+    public function then($onFulfilled = null, $onRejected = null)
+    {
+        return $this->promise->then($onFulfilled, $onRejected);
+    }
+
+    private function run()
+    {
+        try {
+            $cb = $this->callback;
+            $this->promise->resolve($cb());
+        } catch (\Exception $e) {
+            $this->promise->reject($e);
+        }
+    }
+}
diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index b601102..eba8b76 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -3,6 +3,7 @@ namespace GraphQL\Executor;
 
 use GraphQL\Error\Error;
 use GraphQL\Error\InvariantViolation;
+use GraphQL\Executor\Promise\Adapter\SyncPromiseAdapter;
 use GraphQL\Executor\Promise\Promise;
 use GraphQL\Language\AST\DocumentNode;
 use GraphQL\Language\AST\FieldNode;
@@ -10,7 +11,6 @@ use GraphQL\Language\AST\FragmentDefinitionNode;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\OperationDefinitionNode;
 use GraphQL\Language\AST\SelectionSetNode;
-use GraphQL\Executor\Promise\Adapter\GenericPromiseAdapter;
 use GraphQL\Executor\Promise\PromiseAdapter;
 use GraphQL\Schema;
 use GraphQL\Type\Definition\AbstractType;
@@ -68,7 +68,7 @@ class Executor
      */
     public static function getPromiseAdapter()
     {
-        return self::$promiseAdapter ?: (self::$promiseAdapter = new GenericPromiseAdapter());
+        return self::$promiseAdapter ?: (self::$promiseAdapter = new SyncPromiseAdapter());
     }
 
     /**
@@ -112,6 +112,10 @@ class Executor
         $executor = new self($exeContext, $promiseAdapter);
         $result = $executor->executeQuery();
 
+        if ($result instanceof Promise && $promiseAdapter instanceof SyncPromiseAdapter) {
+            $result = $promiseAdapter->wait($result);
+        }
+
         return $result;
     }
 
diff --git a/src/Executor/Promise/Adapter/GenericPromiseAdapter.php b/src/Executor/Promise/Adapter/GenericPromiseAdapter.php
deleted file mode 100644
index 0a4d79a..0000000
--- a/src/Executor/Promise/Adapter/GenericPromiseAdapter.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-namespace GraphQL\Executor\Promise\Adapter;
-
-use GraphQL\Executor\Promise\PromiseAdapter;
-
-class GenericPromiseAdapter implements PromiseAdapter
-{
-    public function isPromise($value)
-    {
-        return false;
-    }
-
-    /**
-     * Accepts value qualified by `isPromise` and returns other promise.
-     *
-     * @param $promise
-     * @param callable|null $onFullFilled
-     * @param callable|null $onRejected
-     * @return mixed
-     */
-    public function then($promise, callable $onFullFilled = null, callable $onRejected = null)
-    {
-        try {
-            if (null !== $onFullFilled) {
-                $promise = $onFullFilled($promise);
-            }
-
-            return $this->createResolvedPromise($promise);
-        } catch (\Exception $e) {
-            if (null !== $onRejected) {
-                $onRejected($e);
-            }
-            return $this->createRejectedPromise($e);
-        }
-    }
-    
-    public function createPromise(callable $resolver)
-    {
-        return $resolver(function ($value) {
-            return $value;
-        });
-    }
-
-    public function createResolvedPromise($promiseOrValue = null)
-    {
-        return $promiseOrValue;
-    }
-
-    public function createRejectedPromise($reason)
-    {
-    }
-
-    public function createPromiseAll($promisesOrValues)
-    {
-    }
-}
diff --git a/src/Executor/Promise/Adapter/SyncPromise.php b/src/Executor/Promise/Adapter/SyncPromise.php
index 65d3111..8b8f6e7 100644
--- a/src/Executor/Promise/Adapter/SyncPromise.php
+++ b/src/Executor/Promise/Adapter/SyncPromise.php
@@ -22,10 +22,16 @@ class SyncPromise
      */
     public static $queue;
 
+    public static function getQueue()
+    {
+        return self::$queue ?: self::$queue = new \SplQueue();
+    }
+
     public static function runQueue()
     {
-        while (self::$queue && !self::$queue->isEmpty()) {
-            $task = self::$queue->dequeue();
+        $q = self::getQueue();
+        while (!$q->isEmpty()) {
+            $task = $q->dequeue();
             $task();
         }
     }
@@ -40,13 +46,6 @@ class SyncPromise
      */
     private $waiting = [];
 
-    public function __construct()
-    {
-        if (!self::$queue) {
-            self::$queue = new \SplQueue();
-        }
-    }
-
     public function reject(\Exception $reason)
     {
         switch ($this->state) {
@@ -73,7 +72,7 @@ class SyncPromise
                 if ($value === $this) {
                     throw new \Exception("Cannot resolve promise with self");
                 }
-                if ($value instanceof self) {
+                if (is_object($value) && method_exists($value, 'then')) {
                     $value->then(
                         function($resolvedValue) {
                             $this->resolve($resolvedValue);
@@ -123,7 +122,7 @@ class SyncPromise
         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 ($descriptor) {
+            self::getQueue()->enqueue(function () use ($descriptor) {
                 /** @var $promise self */
                 list($promise, $onFulfilled, $onRejected) = $descriptor;
 
diff --git a/src/Executor/Promise/Adapter/SyncPromiseAdapter.php b/src/Executor/Promise/Adapter/SyncPromiseAdapter.php
new file mode 100644
index 0000000..08100d4
--- /dev/null
+++ b/src/Executor/Promise/Adapter/SyncPromiseAdapter.php
@@ -0,0 +1,146 @@
+<?php
+namespace GraphQL\Executor\Promise\Adapter;
+
+use GraphQL\Deferred;
+use GraphQL\Error\InvariantViolation;
+use GraphQL\Executor\Promise\Promise;
+use GraphQL\Executor\Promise\PromiseAdapter;
+use GraphQL\Utils;
+
+/**
+ * Class SyncPromiseAdapter
+ *
+ * Allows changing order of field resolution even in sync environments
+ * (by leveraging queue of deferreds and promises)
+ *
+ * @package GraphQL\Executor\Promise\Adapter
+ */
+class SyncPromiseAdapter implements PromiseAdapter
+{
+    /**
+     * @inheritdoc
+     */
+    public function isThenable($value)
+    {
+        return $value instanceof Deferred;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function convert($value)
+    {
+        if (!$value instanceof Deferred) {
+            throw new InvariantViolation('Expected instance of GraphQL\Deferred, got ' . Utils::printSafe($value));
+        }
+        return new Promise($value->promise, $this);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function then(Promise $promise, callable $onFulfilled = null, callable $onRejected = null)
+    {
+        /** @var SyncPromise $promise */
+        $promise = $promise->adoptedPromise;
+        return new Promise($promise->then($onFulfilled, $onRejected), $this);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function createPromise(callable $resolver)
+    {
+        $promise = new SyncPromise();
+
+        $resolver(
+            [$promise, 'resolve'],
+            [$promise, 'reject']
+        );
+
+        return new Promise($promise, $this);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function createResolvedPromise($value = null)
+    {
+        $promise = new SyncPromise();
+        return new Promise($promise->resolve($value), $this);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function createRejectedPromise(\Exception $reason)
+    {
+        $promise = new SyncPromise();
+        return new Promise($promise->reject($reason), $this);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function createPromiseAll(array $promisesOrValues)
+    {
+        $all = new SyncPromise();
+
+        $total = count($promisesOrValues);
+        $count = 0;
+        $result = [];
+
+        foreach ($promisesOrValues as $index => $promiseOrValue) {
+            if ($promiseOrValue instanceof Promise) {
+                $promiseOrValue->then(
+                    function($value) use ($index, &$count, $total, &$result, $all) {
+                        $result[$index] = $value;
+                        $count++;
+                        if ($count >= $total) {
+                            $all->resolve($result);
+                        }
+                    },
+                    [$all, 'reject']
+                );
+            } else {
+                $result[$index] = $promiseOrValue;
+                $count++;
+            }
+        }
+        if ($count === $total) {
+            $all->resolve($result);
+        }
+        return new Promise($all, $this);
+    }
+
+    public function wait(Promise $promise)
+    {
+        $fulfilledValue = null;
+        $rejectedReason = null;
+
+        $promise->then(
+            function ($value) use (&$fulfilledValue) {
+                $fulfilledValue = $value;
+            },
+            function ($reason) use (&$rejectedReason) {
+                $rejectedReason = $reason;
+            }
+        );
+
+        while (
+            $promise->adoptedPromise->state === SyncPromise::PENDING &&
+            !(Deferred::getQueue()->isEmpty() && SyncPromise::getQueue()->isEmpty())
+        ) {
+            Deferred::runQueue();
+            SyncPromise::runQueue();
+        }
+
+        if ($promise->adoptedPromise->state === SyncPromise::PENDING) {
+            throw new InvariantViolation("Could not resolve promise");
+        }
+        if ($rejectedReason instanceof \Exception) {
+            throw $rejectedReason;
+        }
+        return $fulfilledValue;
+    }
+}
diff --git a/src/Utils.php b/src/Utils.php
index 903ffc9..358e6ae 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -242,6 +242,9 @@ class Utils
         if (is_object($var)) {
             return 'instance of ' . get_class($var);
         }
+        if ('' === $var) {
+            return '(empty string)';
+        }
         if (is_scalar($var)) {
             return (string) $var;
         }
diff --git a/tests/Executor/Promise/SyncPromiseAdapterTest.php b/tests/Executor/Promise/SyncPromiseAdapterTest.php
new file mode 100644
index 0000000..863c146
--- /dev/null
+++ b/tests/Executor/Promise/SyncPromiseAdapterTest.php
@@ -0,0 +1,203 @@
+<?php
+namespace GraphQL\Tests\Executor\Promise;
+
+use GraphQL\Deferred;
+use GraphQL\Error\InvariantViolation;
+use GraphQL\Executor\Promise\Adapter\SyncPromise;
+use GraphQL\Executor\Promise\Adapter\SyncPromiseAdapter;
+use GraphQL\Executor\Promise\Promise;
+
+class SyncPromiseAdapterTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @var SyncPromiseAdapter
+     */
+    private $promises;
+
+    public function setUp()
+    {
+        $this->promises = new SyncPromiseAdapter();
+    }
+
+    public function testIsThenable()
+    {
+        $this->assertEquals(true, $this->promises->isThenable(new Deferred(function() {})));
+        $this->assertEquals(false, $this->promises->isThenable(false));
+        $this->assertEquals(false, $this->promises->isThenable(true));
+        $this->assertEquals(false, $this->promises->isThenable(1));
+        $this->assertEquals(false, $this->promises->isThenable(0));
+        $this->assertEquals(false, $this->promises->isThenable('test'));
+        $this->assertEquals(false, $this->promises->isThenable(''));
+        $this->assertEquals(false, $this->promises->isThenable([]));
+        $this->assertEquals(false, $this->promises->isThenable(new \stdClass()));
+    }
+
+    public function testConvert()
+    {
+        $dfd = new Deferred(function() {});
+        $result = $this->promises->convert($dfd);
+
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Promise', $result);
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Adapter\SyncPromise', $result->adoptedPromise);
+
+        try {
+            $this->promises->convert('');
+            $this->fail('Expected exception no thrown');
+        } catch (InvariantViolation $e) {
+            $this->assertEquals('Expected instance of GraphQL\Deferred, got (empty string)', $e->getMessage());
+        }
+    }
+
+    public function testThen()
+    {
+        $dfd = new Deferred(function() {});
+        $promise = $this->promises->convert($dfd);
+
+        $result = $this->promises->then($promise);
+
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Promise', $result);
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Adapter\SyncPromise', $result->adoptedPromise);
+    }
+
+    public function testCreatePromise()
+    {
+        $promise = $this->promises->createPromise(function($resolve, $reject) {});
+
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Promise', $promise);
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Adapter\SyncPromise', $promise->adoptedPromise);
+
+        $promise = $this->promises->createPromise(function($resolve, $reject) {
+            $resolve('A');
+        });
+
+        $this->assertValidPromise($promise, null, 'A', SyncPromise::FULFILLED);
+    }
+
+    public function testCreateFulfilledPromise()
+    {
+        $promise = $this->promises->createResolvedPromise('test');
+        $this->assertValidPromise($promise, null, 'test', SyncPromise::FULFILLED);
+    }
+
+    public function testCreateRejectedPromise()
+    {
+        $promise = $this->promises->createRejectedPromise(new \Exception('test reason'));
+        $this->assertValidPromise($promise, 'test reason', null, SyncPromise::REJECTED);
+    }
+
+    public function testCreatePromiseAll()
+    {
+        $promise = $this->promises->createPromiseAll([]);
+        $this->assertValidPromise($promise, null, [], SyncPromise::FULFILLED);
+
+        $promise = $this->promises->createPromiseAll(['1']);
+        $this->assertValidPromise($promise, null, ['1'], SyncPromise::FULFILLED);
+
+        $promise1 = new SyncPromise();
+        $promise2 = new SyncPromise();
+        $promise3 = $promise2->then(
+            function($value) {
+                return $value .'-value3';
+            }
+        );
+
+        $data = [
+            '1',
+            new Promise($promise1, $this->promises),
+            new Promise($promise2, $this->promises),
+            3,
+            new Promise($promise3, $this->promises),
+            []
+        ];
+
+        $promise = $this->promises->createPromiseAll($data);
+        $this->assertValidPromise($promise, null, null, SyncPromise::PENDING);
+
+        $promise1->resolve('value1');
+        $this->assertValidPromise($promise, null, null, SyncPromise::PENDING);
+        $promise2->resolve('value2');
+        $this->assertValidPromise($promise, null, ['1', 'value1', 'value2', 3, 'value2-value3', []], SyncPromise::FULFILLED);
+    }
+
+    public function testWait()
+    {
+        $called = [];
+
+        $deferred1 = new Deferred(function() use (&$called) {
+            $called[] = 1;
+            return 1;
+        });
+        $deferred2 = new Deferred(function() use (&$called) {
+            $called[] = 2;
+            return 2;
+        });
+
+        $p1 = $this->promises->convert($deferred1);
+        $p2 = $this->promises->convert($deferred2);
+
+        $p3 = $p2->then(function() use (&$called) {
+            $dfd = new Deferred(function() use (&$called) {
+                $called[] = 3;
+                return 3;
+            });
+            return $this->promises->convert($dfd);
+        });
+
+        $p4 = $p3->then(function() use (&$called) {
+            return new Deferred(function() use (&$called) {
+                $called[] = 4;
+                return 4;
+            });
+        });
+
+        $all = $this->promises->createPromiseAll([0, $p1, $p2, $p3, $p4]);
+
+        $result = $this->promises->wait($p2);
+        $this->assertEquals(2, $result);
+        $this->assertEquals(SyncPromise::PENDING, $p3->adoptedPromise->state);
+        $this->assertEquals(SyncPromise::PENDING, $all->adoptedPromise->state);
+        $this->assertEquals([1, 2], $called);
+
+        $expectedResult = [0,1,2,3,4];
+        $result = $this->promises->wait($all);
+        $this->assertEquals($expectedResult, $result);
+        $this->assertEquals([1, 2, 3, 4], $called);
+        $this->assertValidPromise($all, null, [0,1,2,3,4], SyncPromise::FULFILLED);
+    }
+
+    private function assertValidPromise($promise, $expectedNextReason, $expectedNextValue, $expectedNextState)
+    {
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Promise', $promise);
+        $this->assertInstanceOf('GraphQL\Executor\Promise\Adapter\SyncPromise', $promise->adoptedPromise);
+
+        $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();
+
+        if ($expectedNextState !== SyncPromise::PENDING) {
+            $this->assertEquals(!$expectedNextReason, $onFulfilledCalled);
+            $this->assertEquals(!!$expectedNextReason, $onRejectedCalled);
+        }
+
+        $this->assertEquals($expectedNextValue, $actualNextValue);
+        $this->assertEquals($expectedNextReason, $actualNextReason);
+        $this->assertEquals($expectedNextState, $promise->adoptedPromise->state);
+    }
+}
diff --git a/tests/Executor/Promise/SyncPromiseTest.php b/tests/Executor/Promise/SyncPromiseTest.php
index e0566dc..f91ba91 100644
--- a/tests/Executor/Promise/SyncPromiseTest.php
+++ b/tests/Executor/Promise/SyncPromiseTest.php
@@ -252,12 +252,12 @@ class SyncPromiseTest extends \PHPUnit_Framework_TestCase
         $nextPromise3 = $promise->then($onFulfilled, $onRejected);
         $nextPromise4 = $promise->then($onFulfilled, $onRejected);
 
-        $this->assertEquals(SyncPromise::$queue->count(), 0);
+        $this->assertEquals(SyncPromise::getQueue()->count(), 0);
         $this->assertEquals($onFulfilledCount, 0);
         $this->assertEquals($onRejectedCount, 0);
         $promise->resolve(1);
 
-        $this->assertEquals(SyncPromise::$queue->count(), 4);
+        $this->assertEquals(SyncPromise::getQueue()->count(), 4);
         $this->assertEquals($onFulfilledCount, 0);
         $this->assertEquals($onRejectedCount, 0);
         $this->assertEquals(SyncPromise::PENDING, $nextPromise->state);
@@ -266,7 +266,7 @@ class SyncPromiseTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(SyncPromise::PENDING, $nextPromise4->state);
 
         SyncPromise::runQueue();
-        $this->assertEquals(SyncPromise::$queue->count(), 0);
+        $this->assertEquals(SyncPromise::getQueue()->count(), 0);
         $this->assertEquals($onFulfilledCount, 3);
         $this->assertEquals($onRejectedCount, 0);
         $this->assertValidPromise($nextPromise, null, 1, SyncPromise::FULFILLED);