Jetpack Sync: Allow syncing directly during cron

projects/packages/sync/changelog/update-sync-do-sync-cron-bypass-dedicated-route

@@ -0,0 +1,4 @@
+Significance: minor
+Type: changed
+
+Ensure we sync directly during cron.

projects/packages/sync/src/class-sender.php

@@ -358,7 +358,10 @@ private function continue_full_sync_enqueue() {
 	 * @return boolean|WP_Error True if this sync sending was successful, error object otherwise.
 	 */
 	public function do_sync() {
-		if ( ! Settings::is_dedicated_sync_enabled() ) {
+		// Sync directly during cron. We are doing this because otherwise
+		// the dedicated sync flow would be spawning HTTP requests during cron shutdown,
+		// which can be unreliable and cause sync lag for time-sensitive events like updates.
+		if ( ! Settings::is_dedicated_sync_enabled() || Settings::is_doing_cron() ) {
 			$result = $this->do_sync_and_set_delays( $this->sync_queue );
 		} else {
 			$result = Dedicated_Sender::spawn_sync( $this->sync_queue );
@@ -498,7 +501,9 @@ public function do_sync_and_set_delays( $queue ) {
 				$this->set_next_sync_time( time() + self::WPCOM_ERROR_SYNC_DELAY, $queue->id );
 			}
 		} elseif ( $exceeded_sync_wait_threshold && ! Settings::is_doing_cron() ) {
-			// If we actually sent data and it took a while, wait before sending again.
+			// If a send was slow, briefly pause before the next one.
+			// Applies only to Dedicated/Normal Sync to avoid impacting user traffic;
+			// cron jobs are exempt.
 			$this->set_next_sync_time( time() + $this->get_sync_wait_time(), $queue->id );
 		}
 

projects/plugins/jetpack/changelog/update-sync-do-sync-cron-bypass-dedicated-route

@@ -0,0 +1,5 @@
+Significance: patch
+Type: other
+Comment: Tests: Updating sync tests to consider that we now allow syncing directly during cron.
+
+

projects/plugins/jetpack/tests/php/sync/Jetpack_Sync_Sender_Test.php

@@ -47,6 +47,9 @@ public function tear_down() {
 		// Restore default setting.
 		Settings::update_settings( array( 'dedicated_sync_enabled' => 0 ) );
 
+		// Reset cron flag to default behavior.
+		Settings::set_doing_cron( null );
+
 		delete_transient( Dedicated_Sender::DEDICATED_SYNC_CHECK_TRANSIENT );
 
 		// Reset queue.
@@ -624,6 +627,85 @@ public function test_do_sync_errors_if_read_only() {
 		$this->assertTrue( is_wp_error( $response ) );
 	}
 
+	/**
+	 * Test do_sync syncs directly when doing cron even if dedicated sync is enabled.
+	 */
+	public function test_do_sync_runs_inline_when_doing_cron_even_if_dedicated_enabled() {
+		Settings::update_settings( array( 'dedicated_sync_enabled' => 1 ) );
+		Settings::set_doing_cron( true );
+		self::factory()->post->create();
+
+		add_filter( 'pre_http_request', array( $this, 'pre_http_sync_request_spawned' ), 10, 3 );
+		$this->sender->do_sync();
+		remove_filter( 'pre_http_request', array( $this, 'pre_http_sync_request_spawned' ) );
+		Settings::set_doing_cron( null );
+
+		$this->assertFalse( $this->dedicated_sync_request_spawned );
+
+		$event = $this->server_event_storage->get_most_recent_event( 'jetpack_sync_save_post' );
+		$this->assertNotNull( $event );
+	}
+
+	/**
+	 * Test do_sync syncs directly when doing cron even with an active dedicated sync lock.
+	 */
+	public function test_do_sync_runs_inline_when_doing_cron_even_with_dedicated_lock_set() {
+		Settings::update_settings( array( 'dedicated_sync_enabled' => 1 ) );
+		Settings::set_doing_cron( true );
+
+		// Set up an active dedicated sync lock.
+		$lock_option_name = Dedicated_Sender::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME;
+		\Jetpack_Options::update_raw_option( $lock_option_name, 'dummy' );
+		$lock_expires_name = $lock_option_name . '_expires';
+		$expires_at        = microtime( true ) + 10;
+		\Jetpack_Options::update_raw_option( $lock_expires_name, $expires_at );
+
+		self::factory()->post->create();
+
+		add_filter( 'pre_http_request', array( $this, 'pre_http_sync_request_spawned' ), 10, 3 );
+		$this->sender->do_sync();
+		remove_filter( 'pre_http_request', array( $this, 'pre_http_sync_request_spawned' ) );
+		Settings::set_doing_cron( null );
+
+		$this->assertFalse( $this->dedicated_sync_request_spawned );
+
+		$event = $this->server_event_storage->get_most_recent_event( 'jetpack_sync_save_post' );
+		$this->assertNotNull( $event );
+	}
+
+	/**
+	 * Test do_sync does not set throttle when doing cron.
+	 */
+	public function test_do_sync_does_not_set_throttle_when_doing_cron() {
+		// Flush any existing queue items first.
+		$this->sender->do_sync();
+
+		Settings::set_doing_cron( true );
+
+		// Set up throttling config.
+		$this->sender->set_upload_max_rows( 2 );
+		$this->sender->set_sync_wait_time( 2 );
+		$this->sender->set_sync_wait_threshold( 0 );
+
+		add_action( 'demo_action', array( $this->listener, 'action_handler' ) );
+
+		do_action( 'demo_action' );
+		do_action( 'demo_action' );
+		do_action( 'demo_action' );
+		do_action( 'demo_action' );
+
+		// First sync should work and send 2 items.
+		$this->assertTrue( $this->sender->do_sync() );
+		$this->assertCount( 2, $this->server_event_storage->get_all_events( 'demo_action' ) );
+
+		// Second sync should also work (not throttled) because cron doesn't set throttles.
+		$result = $this->sender->do_sync();
+		$this->assertTrue( $result );
+		$this->assertCount( 4, $this->server_event_storage->get_all_events( 'demo_action' ) );
+		Settings::set_doing_cron( null );
+		remove_action( 'demo_action', array( $this->listener, 'action_handler' ) );
+	}
+
 	/**
 	 * Validate that WP_Error is returned in do_full_sync if JETPACK_SYNC_READ_ONLY is defined and true.
 	 */