public override (IReadOnlyCollection <Row>, IReadOnlyCollection <Row>, IReadOnlyCollection <Row>) CalculateChanges()
{
List <Row> inserted = new List <Row>();
List <Row> updated = new List <Row>();
List <Row> deleted = new List <Row>();
Db.Config.DatabaseConnectionString.WithReader(Query, reader =>
{
Dictionary <object[], Row> oldState = new Dictionary <object[], Row>(_data, Schema.RowKeyEqualityComparer);
while (reader.Read())
{
var row = Schema.ReadRow(reader);
if (_data.TryGetValue(row.Key, out Row oldRow))
{
oldState.Remove(row.Key);
if (Schema.RowEqualityComparer.Equals(row, oldRow) == false)
{
updated.Add(row);
_data[row.Key] = row;
}
}
else
{
inserted.Add(row);
_data.Add(row.Key, row);
}
}
deleted = oldState.Values.ToList();
_data.RemoveAll(oldState.Keys);
});
return(inserted, updated, deleted);
}
private void ViewOnInvalidated()
{
var changes = _view.CalculateChanges();
lock (_dataAccessLock)
{
foreach (var row in changes.Item1)
{
var entry = _rowFactory(row);
var key = _keyExtractor(entry);
_rows.Add(key, entry);
}
foreach (var row in changes.Item2)
{
var entry = _rowFactory(row);
var key = _keyExtractor(entry);
_rows[key] = entry;
}
_rows.RemoveAll(changes.Item3.Select(_rowFactory).Select(_keyExtractor));
}
}