@Override
    public long flush(boolean force) throws IOException {
        this.channel.force(force);
        this.flushedSize.set(this.cachedSize.get());
        return this.start + this.flushedSize.get();
    }
Flush file cache to disk.

@param force whether to brush
@return the latest writable position

@throws IOException exception while force data to disk
inlong-tubemq/tubemq-server/src/main/java/org/apache/inlong/tubemq/server/broker/msgstore/disk/FileSegment.java