Calling cancel() on resulting promise should cancel all pending tasks

Author: clue

src/functions.php

@@ -98,7 +98,14 @@ function ($error) use (&$exception, &$rejected, &$wait) {
 function parallel(array $tasks)
 {
     $pending = array();
-    $deferred = new Deferred();
+    $deferred = new Deferred(function () use (&$pending) {
+        foreach ($pending as $promise) {
+            if ($promise instanceof CancellablePromiseInterface) {
+                $promise->cancel();
+            }
+        }
+        $pending = array();
+    });
     $results = array();
     $errored = false;
 
@@ -148,7 +155,13 @@ function parallel(array $tasks)
  */
 function series(array $tasks)
 {
-    $deferred = new Deferred();
+    $pending = null;
+    $deferred = new Deferred(function () use (&$pending) {
+        if ($pending instanceof CancellablePromiseInterface) {
+            $pending->cancel();
+        }
+        $pending = null;
+    });
     $results = array();
 
     /** @var callable():void $next */
@@ -157,7 +170,7 @@ function series(array $tasks)
         $next();
     };
 
-    $next = function () use (&$tasks, $taskCallback, $deferred, &$results) {
+    $next = function () use (&$tasks, $taskCallback, $deferred, &$results, &$pending) {
         if (0 === count($tasks)) {
             $deferred->resolve($results);
             return;
@@ -166,6 +179,7 @@ function series(array $tasks)
         $task = array_shift($tasks);
         $promise = call_user_func($task);
         assert($promise instanceof PromiseInterface);
+        $pending = $promise;
 
         $promise->then($taskCallback, array($deferred, 'reject'));
     };
@@ -181,10 +195,16 @@ function series(array $tasks)
  */
 function waterfall(array $tasks)
 {
-    $deferred = new Deferred();
+    $pending = null;
+    $deferred = new Deferred(function () use (&$pending) {
+        if ($pending instanceof CancellablePromiseInterface) {
+            $pending->cancel();
+        }
+        $pending = null;
+    });
 
     /** @var callable $next */
-    $next = function ($value = null) use (&$tasks, &$next, $deferred) {
+    $next = function ($value = null) use (&$tasks, &$next, $deferred, &$pending) {
         if (0 === count($tasks)) {
             $deferred->resolve($value);
             return;
@@ -193,6 +213,7 @@ function waterfall(array $tasks)
         $task = array_shift($tasks);
         $promise = call_user_func_array($task, func_get_args());
         assert($promise instanceof PromiseInterface);
+        $pending = $promise;
 
         $promise->then($next, array($deferred, 'reject'));
     };

tests/ParallelTest.php

@@ -110,6 +110,29 @@ function () use (&$cancelled) {
         $this->assertSame(1, $cancelled);
     }
 
+    public function testParallelWillCancelPendingPromisesWhenCallingCancelOnResultingPromise()
+    {
+        $cancelled = 0;
+
+        $tasks = array(
+            function () use (&$cancelled) {
+                return new Promise(function () { }, function () use (&$cancelled) {
+                    $cancelled++;
+                });
+            },
+            function () use (&$cancelled) {
+                return new Promise(function () { }, function () use (&$cancelled) {
+                    $cancelled++;
+                });
+            }
+        );
+
+        $promise = React\Async\parallel($tasks);
+        $promise->cancel();
+
+        $this->assertSame(2, $cancelled);
+    }
+
     public function testParallelWithDelayedErrorReturnsPromiseRejectedWithExceptionFromTask()
     {
         $called = 0;

tests/SeriesTest.php

@@ -79,4 +79,27 @@ function () use (&$called) {
 
         $this->assertSame(1, $called);
     }
+
+    public function testSeriesWillCancelFirstPendingPromiseWhenCallingCancelOnResultingPromise()
+    {
+        $cancelled = 0;
+
+        $tasks = array(
+            function () {
+                return new Promise(function ($resolve) {
+                    $resolve();
+                });
+            },
+            function () use (&$cancelled) {
+                return new Promise(function () { }, function () use (&$cancelled) {
+                    $cancelled++;
+                });
+            }
+        );
+
+        $promise = React\Async\series($tasks);
+        $promise->cancel();
+
+        $this->assertSame(1, $cancelled);
+    }
 }

tests/WaterfallTest.php

@@ -86,4 +86,27 @@ function () use (&$called) {
 
         $this->assertSame(1, $called);
     }
+
+    public function testWaterfallWillCancelFirstPendingPromiseWhenCallingCancelOnResultingPromise()
+    {
+        $cancelled = 0;
+
+        $tasks = array(
+            function () {
+                return new Promise(function ($resolve) {
+                    $resolve();
+                });
+            },
+            function () use (&$cancelled) {
+                return new Promise(function () { }, function () use (&$cancelled) {
+                    $cancelled++;
+                });
+            }
+        );
+
+        $promise = React\Async\waterfall($tasks);
+        $promise->cancel();
+
+        $this->assertSame(1, $cancelled);
+    }
 }