private OldVariableStorage getVariableStorage(Address variableAddr) throws IOException {
		if (!variableAddr.isVariableAddress()) {
			throw new IllegalArgumentException();
		}
		if (lastNamespaceCacheID != -1) {
			OldVariableStorage varStore = variableAddrLookupCache.get(variableAddr);
			if (varStore != null) {
				return varStore;
			}
		}
		DBRecord rec = adapter.getRecord(variableAddr.getOffset());
		if (rec == null) {
			return null;
		}
		cacheNamespaceStorage(rec.getLongValue(OldVariableStorageDBAdapterV0V1.NAMESPACE_ID_COL));
		return variableAddrLookupCache.get(variableAddr);
	}
Construct a read-only variable storage manager for the old record format
utilized by the VariableStorage table (NOTE: old table name does not have
a space in the name).  This adapter is intended for use during upgrades
only.
@param handle the database handle.
@param addrMap the address map
@param monitor the task monitor.
@throws IOException if a database error occurs.
@throws CancelledException if the user cancels the upgrade.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/OldVariableStorageManagerDB.java