DataDB getDataDB(DBRecord rec) {
		lock.acquire();
		try {
			if (rec != null) {
				DataDB data = (DataDB) cache.get(rec);
				if (data != null) {
					return data;
				}
				long addr = rec.getKey();
				Address address = addrMap.decodeAddress(addr);
				long datatypeID = rec.getLongValue(DataDBAdapter.DATA_TYPE_ID_COL);
				DataType dt = dataManager.getDataType(datatypeID);
				data = new DataDB(this, cache, addr, address, addr, dt);
				return data;
			}
			return null;

		}
		finally {
			lock.release();
		}
	}
Get the DataDB object from the cache; if it is not in the cache, create a new DB object and 
add it.
@param rec data record
@return the data
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/code/CodeManager.java