Implemented Fiber GC handler

Zend/tests/fibers/gc-cycle-callback.phpt

@@ -0,0 +1,31 @@
+--TEST--
+GC can cleanup cycle when callback references fiber
+--FILE--
+<?php
+
+$ref = new class () {
+    public $fiber;
+
+    public function __destruct() {
+        var_dump('DTOR');
+    }
+};
+
+$fiber = new Fiber(function () use ($ref) {
+    die('UNREACHABLE');
+});
+
+$ref->fiber = $fiber;
+
+$fiber = null;
+$ref = null;
+
+var_dump('COLLECT CYCLES');
+gc_collect_cycles();
+var_dump('DONE');
+
+?>
+--EXPECT--
+string(14) "COLLECT CYCLES"
+string(4) "DTOR"
+string(4) "DONE"

Zend/tests/fibers/gc-cycle-result.phpt

@@ -0,0 +1,42 @@
+--TEST--
+GC can cleanup cycle when fiber result references fiber
+--FILE--
+<?php
+
+$fiber = null;
+$fiber = new Fiber(function () use (&$fiber) {
+    return new class($fiber) {
+        private $fiber;
+
+        public function __construct($fiber) {
+            $this->fiber = $fiber;
+        }
+
+        public function __destruct() {
+            var_dump('DTOR');
+        }
+    };
+});
+
+$fiber->start();
+
+var_dump('COLLECT CYCLES');
+gc_collect_cycles();
+var_dump('DONE');
+
+var_dump($fiber->isTerminated());
+
+unset($fiber);
+
+var_dump('COLLECT CYCLES');
+gc_collect_cycles();
+var_dump('DONE');
+
+?>
+--EXPECT--
+string(14) "COLLECT CYCLES"
+string(4) "DONE"
+bool(true)
+string(14) "COLLECT CYCLES"
+string(4) "DTOR"
+string(4) "DONE"

Zend/zend_fibers.c

@@ -425,7 +425,9 @@ static ZEND_STACK_ALIGNED void zend_fiber_execute(zend_fiber_transfer *transfer)
 
 		zend_call_function(&fiber->fci, &fiber->fci_cache);
 
+		/* Cleanup callback and unset field to prevent GC / duplicate dtor issues. */
 		zval_ptr_dtor(&fiber->fci.function_name);
+		ZVAL_UNDEF(&fiber->fci.function_name);
 
 		if (EG(exception)) {
 			if (!(fiber->flags & ZEND_FIBER_FLAG_DESTROYED)
@@ -516,9 +518,8 @@ static zend_always_inline zend_fiber_transfer zend_fiber_suspend(zend_fiber *fib
 
 static zend_object *zend_fiber_object_create(zend_class_entry *ce)
 {
-	zend_fiber *fiber;
+	zend_fiber *fiber = emalloc(sizeof(zend_fiber));
 
-	fiber = emalloc(sizeof(zend_fiber));
 	memset(fiber, 0, sizeof(zend_fiber));
 
 	zend_object_std_init(&fiber->std, ce);
@@ -565,16 +566,25 @@ static void zend_fiber_object_free(zend_object *object)
 {
 	zend_fiber *fiber = (zend_fiber *) object;
 
-	if (fiber->context.status == ZEND_FIBER_STATUS_INIT) {
-		// Fiber was never started, so we need to release the reference to the callback.
-		zval_ptr_dtor(&fiber->fci.function_name);
-	}
-
+	zval_ptr_dtor(&fiber->fci.function_name);
 	zval_ptr_dtor(&fiber->result);
 
 	zend_object_std_dtor(&fiber->std);
 }
 
+static HashTable *zend_fiber_object_gc(zend_object *object, zval **table, int *num)
+{
+	zend_fiber *fiber = (zend_fiber *) object;
+	zend_get_gc_buffer *buf = zend_get_gc_buffer_create();
+
+	zend_get_gc_buffer_add_zval(buf, &fiber->fci.function_name);
+	zend_get_gc_buffer_add_zval(buf, &fiber->result);
+
+	zend_get_gc_buffer_use(buf, table, num);
+
+	return NULL;
+}
+
 ZEND_METHOD(Fiber, __construct)
 {
 	zend_fiber *fiber = (zend_fiber *) Z_OBJ_P(ZEND_THIS);
@@ -590,12 +600,9 @@ ZEND_METHOD(Fiber, __construct)
 ZEND_METHOD(Fiber, start)
 {
 	zend_fiber *fiber = (zend_fiber *) Z_OBJ_P(ZEND_THIS);
-	zval *params;
-	uint32_t param_count;
-	zend_array *named_params;
 
 	ZEND_PARSE_PARAMETERS_START(0, -1)
-		Z_PARAM_VARIADIC_WITH_NAMED(params, param_count, named_params);
+		Z_PARAM_VARIADIC_WITH_NAMED(fiber->fci.params, fiber->fci.param_count, fiber->fci.named_params);
 	ZEND_PARSE_PARAMETERS_END();
 
 	if (UNEXPECTED(zend_fiber_switch_blocked())) {
@@ -608,10 +615,6 @@ ZEND_METHOD(Fiber, start)
 		RETURN_THROWS();
 	}
 
-	fiber->fci.params = params;
-	fiber->fci.param_count = param_count;
-	fiber->fci.named_params = named_params;
-
 	if (!zend_fiber_init_context(&fiber->context, zend_ce_fiber, zend_fiber_execute, EG(fiber_stack_size))) {
 		RETURN_THROWS();
 	}
@@ -827,6 +830,7 @@ void zend_register_fiber_ce(void)
 	zend_fiber_handlers = std_object_handlers;
 	zend_fiber_handlers.dtor_obj = zend_fiber_object_destroy;
 	zend_fiber_handlers.free_obj = zend_fiber_object_free;
+	zend_fiber_handlers.get_gc = zend_fiber_object_gc;
 	zend_fiber_handlers.clone_obj = NULL;
 
 	zend_ce_fiber_error = register_class_FiberError(zend_ce_error);