如果我们开始一个事务,然后执行一些db操作,比如说insert,并且发生异常,如果我不在catch / exception处理程序中调用transaction.rollback(),那么事务会自动回滚吗?
即使事务被回滚,是否会导致内存泄漏,即事务对象和连接对象在内存中以原始状态挂起,直到垃圾收集器启动?
CREATE TABLE [Friend]
(
[ID] [int] IDENTITY(1,1) NOT NULL,
[FullName] [varchar](50) NOT NULL,
[Phone] [varchar](50) NULL,
)
客户端:
namespace Client
{
class Program
{
static void Main(string[] args)
{
DaContract Impl = new Impl();
Impl.AddFriend(new Friend("Someone", "100"));
Impl.AddFriend(new Friend("Someone else"));
Console.ReadLine();
}
}
}
SERVER:
using System;
using MyLib.DataAccess;
using System.Data;
namespace TestTransactionAndConnectionStateOnException
{
public class Friend
{
public string FullName;
public string Phone;
public Friend(string fullName): this(fullName, null) {}
public Friend(string fullName, string phone)
{
this.FullName = fullName;
this.Phone = phone;
}
}
public interface DaContract
{
int AddFriend( Friend f );
int UpdatePhone(string fullName, string phone);
}
public class Impl: DaContract
{
Mediator _m;
public Impl() { this._m = new Mediator(); }
public int AddFriend( Friend f )
{
int ret = 0;
try
{
ret = this._m.AddFriend( f );
}
catch(Exception ex)
{
HandleException(ex);
}
return ret;
}
public int UpdatePhone(string fullName, string phone)
{
int ret = 0;
try
{
ret = this._m.UpdatePhone(fullName, phone);
}
catch(Exception ex)
{
HandleException(ex);
}
return ret;
}
public void HandleException(Exception ex)
{
/* see the transaction state */
/* see connection state */
/* do nothing and let the client call another method to initiate a new
* transaction and a new connection */
}
}
public class Mediator
{
private string _connectionString = "Data Source=localhost;Integrated Security=SSPI;Initial Catalog=MyFriends";
private Manager _m = new Manager();
public int AddFriend( Friend f )
{
int ret = 0;
using (ISession session = SessionFactory.Create(SessionType.Ado, this._connectionString))
{
session.BeginTransaction();
ret = this._m.AddFriend(f, session);
session.CommitTransaction();
}
return ret;
}
public int UpdatePhone(string fullName, string phone)
{
int ret = 0;
using (ISession session = SessionFactory.Create(SessionType.Ado, this._connectionString))
{
session.BeginTransaction();
ret = this._m.UpdateFriend(fullName, phone, session);
session.CommitTransaction();
}
return ret;
}
}
public class Manager
{
public int AddFriend(Friend f, ISession session) { return Handler.Instance.AddFriend(f, session); }
public int UpdateFriend(string fullName, string phone, ISession session) { return Handler.Instance.UpdatePhone(fullName, phone, session); }
}
public class Handler
{
private static Handler _handler = null;
private Handler() {}
public static Handler Instance
{
get
{
if (_handler == null)
_handler = new Handler();
return _handler;
}
}
public int AddFriend( Friend f, ISession session )
{
/* check session, transaction and connection states here */
Console.WriteLine(session.Connection.State.ToString());
int ret = 0;
/* Add the friend */
IDbCommand command = session.CreateCommand();
command.CommandType = CommandType.Text;
command.CommandText = string.Format("INSERT INTO Friend(FullName, Phone) values('{0}', '{1}')", f.FullName, f.Phone);
ret = command.ExecuteNonQuery();
/* throw an exception just for the heck of it (don't dispose off ISession yet) */
if (string.Compare(f.FullName, "Someone", true) == 0)
throw new Exception("Fake exception. Friend value can't be 'Someone'");
return ret;
}
public int UpdatePhone(string fullName, string phone, ISession session )
{
return 0;
}
}
}
由于字数限制,我无法在评论部分发布代码,因为它搞砸了所有格式。
答案 0 :(得分:3)
如果事务在未提交的情况下处理,则将回滚该事务。因此,只要你使用using()开始你的事务,或者有一个调用Dispose()的finally块,它就会在异常的情况下自动回滚。
如果你没有处理事务/连接,它最终将由垃圾收集器回收,但在此之前会在内存中挂起。 (实际上,托管的SqlTransaction对象将在内存中挂起,直到GC无论如何都会出现;但是处理可以确保尽早清理非托管事务/连接资源,释放服务器端资源并释放连接以便重用。)
答案 1 :(得分:1)
CREATE TABLE [Friend]
(
[ID] [int] IDENTITY(1,1) NOT NULL,
[FullName] [varchar](50) NOT NULL,
[Phone] [varchar](50) NULL,
)
namespace Client
{
class Program
{
static void Main(string[] args)
{
DaContract Impl = new Impl();
Impl.AddFriend(new Friend("Someone", "100"));
Impl.AddFriend(new Friend("Someone else"));
Console.ReadLine();
}
}
}
using System;
using MyLib.DataAccess;
using System.Data;
namespace TestTransactionAndConnectionStateOnException
{
public class Friend
{
public string FullName;
public string Phone;
public Friend(string fullName): this(fullName, null) {}
public Friend(string fullName, string phone)
{
this.FullName = fullName;
this.Phone = phone;
}
}
public interface DaContract
{
int AddFriend( Friend f );
int UpdatePhone(string fullName, string phone);
}
public class Impl: DaContract
{
Mediator _m;
public Impl() { this._m = new Mediator(); }
public int AddFriend( Friend f )
{
int ret = 0;
try
{
ret = this._m.AddFriend( f );
}
catch(Exception ex)
{
HandleException(ex);
}
return ret;
}
public int UpdatePhone(string fullName, string phone)
{
int ret = 0;
try
{
ret = this._m.UpdatePhone(fullName, phone);
}
catch(Exception ex)
{
HandleException(ex);
}
return ret;
}
public void HandleException(Exception ex)
{
/* see the transaction state */
/* see connection state */
/* do nothing and let the client call another method to initiate a new
* transaction and a new connection */
}
}
public class Mediator
{
private string _connectionString = "Data Source=localhost;Integrated Security=SSPI;Initial Catalog=MyFriends";
private Manager _m = new Manager();
public int AddFriend( Friend f )
{
int ret = 0;
using (ISession session = SessionFactory.Create(SessionType.Ado, this._connectionString))
{
session.BeginTransaction();
ret = this._m.AddFriend(f, session);
session.CommitTransaction();
}
return ret;
}
public int UpdatePhone(string fullName, string phone)
{
int ret = 0;
using (ISession session = SessionFactory.Create(SessionType.Ado, this._connectionString))
{
session.BeginTransaction();
ret = this._m.UpdateFriend(fullName, phone, session);
session.CommitTransaction();
}
return ret;
}
}
public class Manager
{
public int AddFriend(Friend f, ISession session) { return Handler.Instance.AddFriend(f, session); }
public int UpdateFriend(string fullName, string phone, ISession session) { return Handler.Instance.UpdatePhone(fullName, phone, session); }
}
public class Handler
{
private static Handler _handler = null;
private Handler() {}
public static Handler Instance
{
get
{
if (_handler == null)
_handler = new Handler();
return _handler;
}
}
public int AddFriend( Friend f, ISession session )
{
/* check session, transaction and connection states here */
Console.WriteLine(session.Connection.State.ToString());
int ret = 0;
/* Add the friend */
IDbCommand command = session.CreateCommand();
command.CommandType = CommandType.Text;
command.CommandText = string.Format("INSERT INTO Friend(FullName, Phone) values('{0}', '{1}')", f.FullName, f.Phone);
ret = command.ExecuteNonQuery();
/* throw an exception just for the heck of it (don't dispose off ISession yet) */
if (string.Compare(f.FullName, "Someone", true) == 0)
throw new Exception("Fake exception. Friend value can't be 'Someone'");
return ret;
}
public int UpdatePhone(string fullName, string phone, ISession session )
{
return 0;
}
}
}
由于字数限制,我无法在评论部分发布代码,因为它搞砸了所有格式。