close method
Closes all active streams and clears internal state.
Called by Database.close. After this, existing subscriber streams receive a done event and no new streams can be created.
Implementation
void close() {
for (final entry in _entries.values) {
for (final sub in entry.subscribers) {
if (!sub.isClosed) sub.close();
}
entry.subscribers.clear();
}
_entries.clear();
_tableToKeys.clear();
}