public static ConnectionWrapper GetConnection(string connectionString, DbProviderFactory dbProvider)
{
Transaction currentTran = Transaction.Current;
if (currentTran == null)
{
return(new ConnectionWrapper(CreateConnection(connectionString, dbProvider)));
}
// tranConnections是一个多线程安全的字典对象，尽量必免使用锁带来的性能损耗。
Dictionary <string, ConnectionWrapper> connWrappers =
tranConnections.GetOrAdd(currentTran, x =>
{
x.TransactionCompleted += OnTransactionCompleted;
return(new Dictionary <string, ConnectionWrapper>());
});
// connWrappers通常不会在并发环境下操作，也就不会发生锁竞争，对于锁带来的性能损耗可以忽略。此处上一把锁主要是为了安全起见。
ConnectionWrapper connWrapper;
lock (connWrappers)
{
if (!connWrappers.TryGetValue(connectionString, out connWrapper))
{
connWrapper = new ConnectionWrapper(CreateConnection(connectionString, dbProvider));
connWrappers.Add(connectionString, connWrapper);
}
connWrapper.AddReference();
}
return(connWrapper);
}
/// <summary>
///
/// </summary>
/// <param name="connnection"></param>
/// <param name="datareader"></param>
public DataReaderWrapper(ConnectionWrapper connnection, IDataReader datareader)
{
this.connnection = connnection;
this.datareader = datareader;
this.connnection.AddReference();
}
/// <summary>
///
/// </summary>
/// <param name="connectionString"></param>
/// <returns></returns>
public ConnectionWrapper GetWrapperedConnection(string connectionString)
{
return(ConnectionWrapper.GetConnection(connectionString, DbProviderFactory));
}
