Add traits to forbid cloning and serialization (#388)

src/CompositeCancellation.php

@@ -6,6 +6,9 @@
 
 final class CompositeCancellation implements Cancellation
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     /** @var array<int, array{Cancellation, string}> */
     private array $cancellations = [];
 

src/DeferredCancellation.php

@@ -37,6 +37,9 @@
  */
 final class DeferredCancellation
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     private readonly Internal\Cancellable $source;
     private readonly Cancellation $cancellation;
 

src/DeferredFuture.php

@@ -7,6 +7,9 @@
  */
 final class DeferredFuture
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     /** @var Internal\FutureState<T> */
     private readonly Internal\FutureState $state;
 

src/ForbidCloning.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Amp;
+
+trait ForbidCloning
+{
+    final protected function __clone()
+    {
+        throw new \Error(__CLASS__ . ' does not support cloning');
+    }
+}

src/ForbidSerialization.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Amp;
+
+trait ForbidSerialization
+{
+    final public function __serialize(): never
+    {
+        throw new \Error(__CLASS__ . ' does not support serialization');
+    }
+}

src/Future.php

@@ -11,6 +11,9 @@
  */
 final class Future
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     /**
      * Iterate over the given futures in completion order.
      *

src/Internal/Cancellable.php

@@ -4,6 +4,8 @@
 
 use Amp\Cancellation;
 use Amp\CancelledException;
+use Amp\ForbidCloning;
+use Amp\ForbidSerialization;
 use Revolt\EventLoop;
 
 /**
@@ -13,6 +15,9 @@
  */
 final class Cancellable implements Cancellation
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     private string $nextId = "a";
 
     /** @var \Closure[] */

src/Internal/FutureIterator.php

@@ -3,6 +3,8 @@
 namespace Amp\Internal;
 
 use Amp\Cancellation;
+use Amp\ForbidCloning;
+use Amp\ForbidSerialization;
 use Amp\Future;
 use Amp\NullCancellation;
 use Revolt\EventLoop;
@@ -15,6 +17,9 @@
  */
 final class FutureIterator
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     /**
      * @var FutureIteratorQueue<Tk, Tv>
      */

src/Internal/WrappedCancellation.php

@@ -3,12 +3,17 @@
 namespace Amp\Internal;
 
 use Amp\Cancellation;
+use Amp\ForbidCloning;
+use Amp\ForbidSerialization;
 
 /**
  * @internal
  */
 final class WrappedCancellation implements Cancellation
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     public function __construct(
         private readonly Cancellation $cancellation
     ) {

src/TimeoutCancellation.php

@@ -9,6 +9,9 @@
  */
 final class TimeoutCancellation implements Cancellation
 {
+    use ForbidCloning;
+    use ForbidSerialization;
+
     private readonly string $watcher;
 
     private readonly Cancellation $cancellation;

test/Cancellation/CompositeCancellationTest.php

@@ -34,7 +34,7 @@ public function testBenchmark(): void
 
             // Asserts
             if ($firstMemoryMeasure > 0) {
-                self::assertEquals($firstMemoryMeasure, \memory_get_usage(true));
+                self::assertLessThanOrEqual($firstMemoryMeasure, \memory_get_usage(true));
             }
         }
     }