@Override
            public void onDone(CompletionCode code, String message) {
                super.onDone(code, message);
                phaser.arriveAndAwaitAdvance(); // Synchronize with the reindexer control thread.
            }
Starts and tracks reprocessing of ready document types until done, or interrupted.
clustercontroller-reindexer/src/main/java/ai/vespa/reindexing/Reindexer.java