/**
* This method is called before writing to the map. The default implementation checks whether
* writing is allowed, and tries to detect concurrent modification.
*
* @throws UnsupportedOperationException if the map is read-only, or if another thread is
* concurrently writing
*/
protected void beforeWrite() {
if (readOnly) {
checkOpen();
throw DataUtils.newUnsupportedOperationException("This map is read-only");
}
checkConcurrentWrite();
writing = true;
store.beforeWrite();
}
