public boolean reset(final long nextLogIndex) {
        this.flushStatusCheckpoint.destroy();
        this.fileManager.reset(nextLogIndex);
        doCheckpoint();
        return true;
    }
Flush db files and wait for flushPosition >= maxExpectedFlushPosition
@return true if flushPosition >= maxExpectedFlushPosition
jraft-extension/java-log-storage-impl/src/main/java/com/alipay/sofa/jraft/storage/db/AbstractDB.java