@Override
    public synchronized void doFlush() {
      // this is called by flusher thread so have it wait
      try {
        super.waitForFlush();
      } catch (InterruptedException ignore) {
        Thread.currentThread().interrupt();
      }
    }
Return true if a non-zero value is found and the decrement was done.
geode-core/src/main/java/org/apache/geode/internal/cache/DiskStoreImpl.java