in.remove();
} else if (msg instanceof FileRegion) {
FileRegion region = (FileRegion) msg;
long transfered = region.transfered();
doWriteFileRegion(region);
in.progress(region.transfered() - transfered);
in.remove();
} else {
in.remove(new UnsupportedOperationException(
"unsupported message type: " + StringUtil.simpleClassName(msg)));
}