Improve await() for asyc() to avoid unneeded futureTick() calls

Author: clue

src/SimpleFiber.php

@@ -10,6 +10,7 @@
 final class SimpleFiber implements FiberInterface
 {
     private static ?\Fiber $scheduler = null;
+    private static ?\Closure $suspend = null;
     private ?\Fiber $fiber = null;
 
     public function __construct()
@@ -20,29 +21,45 @@ public function __construct()
     public function resume(mixed $value): void
     {
         if ($this->fiber === null) {
+            $suspend = static fn() => $value;
             if (\Fiber::getCurrent() !== self::$scheduler) {
-                Loop::futureTick(static fn() => \Fiber::suspend(static fn() => $value));
+                self::$suspend = $suspend;
             } else {
-                \Fiber::suspend(static fn() => $value);
+                \Fiber::suspend($suspend);
             }
             return;
         }
 
         $this->fiber->resume($value);
+
+        if (self::$suspend) {
+            $suspend = self::$suspend;
+            self::$suspend = null;
+
+            \Fiber::suspend($suspend);
+        }
     }
 
     public function throw(\Throwable $throwable): void
     {
         if ($this->fiber === null) {
+            $suspend = static fn() => throw $throwable;
             if (\Fiber::getCurrent() !== self::$scheduler) {
-                Loop::futureTick(static fn() => \Fiber::suspend(static fn() => throw $throwable));
+                self::$suspend = $suspend;
             } else {
-                \Fiber::suspend(static fn() => throw $throwable);
+                \Fiber::suspend($suspend);
             }
             return;
         }
 
         $this->fiber->throw($throwable);
+
+        if (self::$suspend) {
+            $suspend = self::$suspend;
+            self::$suspend = null;
+
+            \Fiber::suspend($suspend);
+        }
     }
 
     public function suspend(): mixed

tests/AwaitTest.php

@@ -6,6 +6,7 @@
 use React\EventLoop\Loop;
 use React\Promise\Deferred;
 use React\Promise\Promise;
+use function React\Async\async;
 
 class AwaitTest extends TestCase
 {
@@ -68,6 +69,34 @@ public function testAwaitThrowsExceptionImmediatelyWhenPromiseIsRejected(callabl
         }
     }
 
+    /**
+     * @dataProvider provideAwaiters
+     */
+    public function testAwaitAsyncThrowsExceptionImmediatelyWhenPromiseIsRejected(callable $await)
+    {
+        $deferred = new Deferred();
+
+        $ticks = 0;
+        Loop::futureTick(function () use (&$ticks) {
+            ++$ticks;
+            Loop::futureTick(function () use (&$ticks) {
+                ++$ticks;
+            });
+        });
+
+        Loop::futureTick(fn() => $deferred->reject(new \RuntimeException()));
+
+        $promise = async(function () use ($deferred, $await) {
+            return $await($deferred->promise());
+        })();
+
+        try {
+            $await($promise);
+        } catch (\RuntimeException $e) {
+            $this->assertEquals(1, $ticks);
+        }
+    }
+
     /**
      * @dataProvider provideAwaiters
      */
@@ -176,6 +205,31 @@ public function testAwaitReturnsValueImmediatelyWhenPromiseIsFulfilled(callable
         $this->assertEquals(1, $ticks);
     }
 
+    /**
+     * @dataProvider provideAwaiters
+     */
+    public function testAwaitAsyncReturnsValueImmediatelyWhenPromiseIsFulfilled(callable $await)
+    {
+        $deferred = new Deferred();
+
+        $ticks = 0;
+        Loop::futureTick(function () use (&$ticks) {
+            ++$ticks;
+            Loop::futureTick(function () use (&$ticks) {
+                ++$ticks;
+            });
+        });
+
+        Loop::futureTick(fn() => $deferred->resolve(42));
+
+        $promise = async(function () use ($deferred, $await) {
+            return $await($deferred->promise());
+        })();
+
+        $this->assertEquals(42, $await($promise));
+        $this->assertEquals(1, $ticks);
+    }
+
     /**
      * @dataProvider provideAwaiters
      */