Merge pull request woocommerce#26878 from woocommerce/fix/26787

Moved synchronous webhook execution into a shutdown function

includes/wc-webhook-functions.php

@@ -8,6 +8,23 @@
 
 defined( 'ABSPATH' ) || exit;
 
+/**
+ * Process the synchronous web hooks at the end of the request.
+ *
+ * @since 4.4.0
+ */
+function wc_webhook_execute_synchronous_queue() {
+	global $wc_queued_sync_webhooks;
+	if ( empty( $wc_queued_sync_webhooks ) ) {
+		return;
+	}
+
+	foreach ( $wc_queued_sync_webhooks as $data ) {
+		$data['webhook']->deliver( $data['arg'] );
+	}
+}
+register_shutdown_function( 'wc_webhook_execute_synchronous_queue' );
+
 /**
  * Process webhook delivery.
  *
@@ -33,8 +50,16 @@ function wc_webhook_process_delivery( $webhook, $arg ) {
 			WC()->queue()->add( 'woocommerce_deliver_webhook_async', $queue_args, 'woocommerce-webhooks' );
 		}
 	} else {
-		// Deliver immediately.
-		$webhook->deliver( $arg );
+		// We need to queue the webhook so that it can be ran after the request has finished processing.
+		// This must be done in order to keep parity with how they are executed asynchronously.
+		global $wc_queued_sync_webhooks;
+		if ( ! isset( $wc_queued_sync_webhooks ) ) {
+			$wc_queued_sync_webhooks = array();
+		}
+		$wc_queued_sync_webhooks[] = array(
+			'webhook' => $webhook,
+			'arg'     => $arg,
+		);
 	}
 }
 add_action( 'woocommerce_webhook_process_delivery', 'wc_webhook_process_delivery', 10, 2 );

tests/legacy/unit-tests/webhooks/functions.php

@@ -238,6 +238,29 @@ public function test_woocommerce_webhook_is_delivered_only_once() {
 		remove_action( 'woocommerce_webhook_process_delivery', array( $this, 'woocommerce_webhook_process_delivery' ), 1, 2 );
 	}
 
+	/**
+	 * Verify that a webhook is queued when intended to be delivered synchronously. This allows us to then execute them
+	 * all in a `register_shutdown_function` after the request has processed. Since async jobs are handled in
+	 * this way, we can be more confident that it is consistent.
+	 */
+	public function test_woocommerce_webhook_synchronous_is_queued() {
+		add_filter( 'woocommerce_webhook_deliver_async', '__return_false' );
+		$webhook = wc_get_webhook( $this->create_webhook( 'customer.created' )->get_id() );
+		wc_load_webhooks( 'active' );
+		add_action( 'woocommerce_webhook_process_delivery', array( $this, 'woocommerce_webhook_process_delivery' ), 1, 2 );
+		$customer = WC_Helper_Customer::create_customer( 'test1', 'pw1', '[email protected]' );
+
+		global $wc_queued_sync_webhooks;
+		$this->assertCount( 1, $wc_queued_sync_webhooks );
+		$this->assertEquals( $webhook->get_id(), $wc_queued_sync_webhooks[0]['webhook']->get_id() );
+		$this->assertEquals( $customer->get_id(), $wc_queued_sync_webhooks[0]['arg'] );
+
+		$wc_queued_sync_webhooks = null;
+		remove_filter( 'woocommerce_webhook_deliver_async', '__return_false' );
+		$webhook->delete( true );
+		$customer->delete( true );
+	}
+
 	/**
 	 * Helper function to keep track of which webhook (and corresponding arg) has been delivered
 	 * within the current request.