对于我的基于网络的项目，我需要锁定一些代码以防止同时访问。 这是我的代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Utility;
using DataBaseConnection;
using System.Net.Sockets;
using System.Data;
using System.IO;
namespace SunHavenClasses
{
public delegate void CtatReceiveDelegate(string message);
public class ServerHandlerClass
{
public event CtatReceiveDelegate OnChatDataReceive;
private Settings settings;
private DBCon con;
private Utility.Network.Server server;
private Dictionary<string, Socket> UsersOnline;
private Dictionary<string, int> unAuthenticatedIps;
private string pass = "logisoftlogicielbarundipankar";
public ServerHandlerClass(Settings s)
{
settings = s;
con = s.GetConnection();
server = new Utility.Network.Server(7777);
server.ClientConnectEventArise += OnUserConnect;//.OnClientConnect(OnUserConnect);
server.ClientDataReceiveEventArise += OnUsersDataReceive;
server.ClientDataSendEventArise += OnDataSendToUser;
server.ClientDisconnectEventArise += OnUserDisconnect;
server.OnBlockUser += OnUserBlocked;
UsersOnline = new Dictionary<string, Socket>();
unAuthenticatedIps = new Dictionary<string, int>();
}
private void OnUserConnect(Utility.Network.ServerEventArguments e)
{
Stream data = Utility.Serializing.Serialize(settings);
data = ZipNEncrypt.Zip(new string[] { "settings" }, new Stream[] { data }, pass);
server.Send(data, e.ClientSocket);
//MessageBox.Show(e.ClientSocket.RemoteEndPoint.ToString() + " is Connected!!");
}
private void OnUsersDataReceive(Utility.Network.ServerEventArguments e)
{
Dictionary<string, System.IO.Stream> data = ZipNEncrypt.Unzip(e.Data, pass);
User user;
try
{
user = (User)Serializing.Deserialize(data["user"]);
if (!UsersOnline.ContainsKey(user.GetUserId()))
{
server.BlockIp(e.ClientSocket);
return;
}
data.Remove("user");
}
catch (Exception)
{
bool passed = true;
foreach (string key in data.Keys)
{
if (key.Equals("LoggedIn")) break;
string[] str = key.Split('_');
if (str[0].Equals("GetData"))
{
string strr = (string)Serializing.Deserialize(data[key]);
if (strr.Contains("Users"))
{
string ip = e.ClientSocket.RemoteEndPoint.ToString().Split(':')[0];
/*CHANGE 1.2.10 00:14*/
lock (unAuthenticatedIps)
{
if (!unAuthenticatedIps.ContainsKey(ip))
{
unAuthenticatedIps.Add(ip, 1);
}
else unAuthenticatedIps[ip] += 1;
if (unAuthenticatedIps[ip] >= 11) passed = false;
}
/*CHANGE 1.2.10 00:14*/
break;
}
else passed = false;//server.AddBlockedIp(ip);
}
else passed = false;
}
if (!passed)
{
server.BlockIp(e.ClientSocket);
}
}
foreach (string key in data.Keys)
{
if (key.Equals("LoggedIn"))
{
try
{
User u = (User)Serializing.Deserialize(data["LoggedIn"]);
if (!UsersOnline.ContainsKey(u.GetUserId()))
{
if (User.ValidateUser(u.GetUserId(), u.GetPassword(), con))
{
/*CHANGE 1.2.10 00:14*/
lock (UsersOnline)
{
UsersOnline.Add(u.GetUserId(), e.ClientSocket);
string ip = e.ClientSocket.RemoteEndPoint.ToString().Split(':')[0];
Utility.Log.Write("UserLog.log", u.GetUserId() +
" Logged In From Ip " + ip);
}
/*CHANGE 1.2.10 00:14*/
}
else
{
server.BlockIp(e.ClientSocket);
return;
}
}
else
{
Stream tmpStream = Serializing.Serialize("Same User");
tmpStream = ZipNEncrypt.Zip(new string[] { key + "ERROR_SameUser" },
new Stream[] { tmpStream }, pass);
server.Send(tmpStream, e.ClientSocket);
return;
}
}
catch (Exception) { }
return;
}
else if (key.Equals("chat"))
{
string ip = e.ClientSocket.RemoteEndPoint.ToString().Split(':')[0];
string message = ip + " : "+ (string)Serializing.Deserialize(data[key]);
OnChatDataReceive(message);
return;
}
string[] str = key.Split('_');
Stream dataStream = null;
object obj = null;
try
{
if (str[0].StartsWith("Get"))
{
if (str[0].Equals("GetData"))
{
string query = (string)Serializing.Deserialize(data[key]);
obj = con.GetData(query);
}
else if (str[0].Equals("GetColumn"))
{
string query = (string)Serializing.Deserialize(data[key]);
string[] tmp = query.Split('%');
obj = con.GetColumn(tmp[0], tmp[1]);
}
else if (str[0].Equals("GetColumnDistrinctValue"))
{
string query = (string)Serializing.Deserialize(data[key]);
string[] tmp = query.Split('%');
obj = con.GetColumnDistrinctValue(tmp[0], tmp[1]);
}
}
else
{
lock (this)
{
if (str[0].Equals("ExecuteUpdate"))
{
if (str[1].Equals("Query"))
{
Query query = (Query)Serializing.Deserialize(data[key]);
obj = con.ExecuteUpdate(query);
}
else if (str[1].Equals("String"))
{
string query = (string)Serializing.Deserialize(data[key]);
obj = con.ExecuteUpdate(query);
}
}
else if (str[0].Equals("ExecuteBatchUpdate"))
{
if (str[1].Equals("Query"))
{
Query[] query = (Query[])Serializing.Deserialize(data[key]);
obj = con.ExecuteBatchUpdate(query);
}
else if (str[1].Equals("String"))
{
string[] query = (string[])Serializing.Deserialize(data[key]);
obj = con.ExecuteBatchUpdate(query);
}
}
else if (str[0].Equals("ExecutrInsert"))
{
Query query = (Query)Serializing.Deserialize(data[key]);
obj = con.ExecutrInsert(query);
}
}
}
dataStream = Serializing.Serialize(obj);
dataStream = ZipNEncrypt.Zip(new string[] { key },
new Stream[] { dataStream }, pass);
}
catch (Exception ex)
{
dataStream = Serializing.Serialize(ex.Message);
dataStream = ZipNEncrypt.Zip(new string[] { key + "_ERROR" },
new Stream[] { dataStream }, pass);
}
server.Send(dataStream, e.ClientSocket);
}
}
private void OnDataSendToUser(Utility.Network.ServerEventArguments e)
{
}
private void OnUserDisconnect(Utility.Network.ServerEventArguments e)
{
//System.Windows.Forms.MessageBox.Show("Disconnected");
string ip = e.ClientSocket.RemoteEndPoint.ToString().Split(':')[0];
/*CHANGE 1.2.10 00:14*/
lock (unAuthenticatedIps)
{
if (unAuthenticatedIps.ContainsKey(ip))
unAuthenticatedIps.Remove(ip);
}
lock (UsersOnline)
{
foreach (string key in UsersOnline.Keys)
if (UsersOnline[key].Equals(e.ClientSocket))
{
Utility.Log.Write("UserLog.log", key + " Logged Out From Ip " + ip);
UsersOnline.Remove(key);
break;
}
}
/*CHANGE 1.2.10 00:14*/
}
private void OnUserBlocked(Utility.Network.ServerEventArguments e)
{
string ip = e.ClientSocket.RemoteEndPoint.ToString().Split(':')[0];
Utility.Log.Write("UserLog.log", "Blocked For Illegal Access From Ip " + ip);
}
public void Send(Stream dataStream)
{
foreach (string key in UsersOnline.Keys)
{
try
{
server.Send(dataStream, UsersOnline[key]);
}
catch (Exception) { }
}
}
public void Send(Stream dataStream, Socket client)
{
try
{
server.Send(dataStream, client);
}
catch (Exception) { }
}
/*changed*/
public bool AddUser(string userId, Socket socket)
{
if (UsersOnline.ContainsKey(userId)) return false;
UsersOnline.Add(userId, null);
return true;
}
public void RemoveUser(string userId)
{
if (!UsersOnline.ContainsKey(userId) || UsersOnline[userId] != null) return;
UsersOnline.Remove(userId);
}
}
}
现在我不确定我是否正确使用锁。请给我一些建议。 感谢。
答案 0 :(得分：1)
你正确地使用它一些。 unAuthenticatedIps受到正确保护，但UsersOnline不受保护。让我们考虑两个并行线程通过您的代码：
Thread A Thread B
-------- --------
if (!UsersOnline.ContainsKey(u.GetUserId()) Statement's true Statement's true
{
lock (UsersOnline) Get lock Block
{
UsersOnline.Add UsersOnline.Add
} Release Lock
} Get lock
UsersOnline.Add
Release lock
请注意，线程A和B都修改UsersOnline字典。这种结构可以恰当地保护该对象：
if (!UsersOnline.ContainsKey(u.GetUserId()))
{
if (User.ValidateUser(u.GetUserId(), u.GetPassword(), con))
{
lock (UsersOnline)
{
// Note the additional check in case another thread
// added this already
if (!UsersOnline.ContainsKey(u.GetUserId())
{
UsersOnline.Add(u.GetUserId(), e.ClientSocket);
// ...
}
}
}
else
{
server.BlockIp(e.ClientSocket);
return;
}
}
就最后一次锁定而言（lock (this)），我还不明白为什么你会需要它。 str和obj都是局部变量，因此您不必担心它们会被单独的线程修改。而且，正如其他人所说，不建议锁定this。
答案 1 :(得分：1)
我猜你读的比你写的要多得多？如果是这样，ReaderWriterLockSlim可能更适合减少阻塞（当您只想检查密钥时读取，并写入以操纵数据）。
我的意思是你可以先用读取进行双重检查锁定，然后如果失败则进行写锁定，再次检查并在必要时添加。
另外 - lock(this)通常不赞成;有一个单独的锁定对象是首选。
请注意，为了有效，所有访问必须尊重锁定;例如，有些地方UsersOnline被锁定，有些地方没有锁定就被访问;那些第二种情况可能会在一个混乱的混乱中爆炸。
例如：
if (!UsersOnline.ContainsKey(u.GetUserId()))
{
if (User.ValidateUser(u.GetUserId(), u.GetPassword(), con))
{
/*CHANGE 1.2.10 00:14*/
lock (UsersOnline)
{
UsersOnline.Add(u.GetUserId(), e.ClientSocket);
在上文中，如果两个线程可能正在查看UsersOnline，那么在没有锁定的情况下尝试ContainsKey您已经失败了。当你这样做的时候，另一个线程正在改变状态....... 繁荣。
答案 2 :(得分：1)
首先，您的代码根本不是线程安全的。在您的代码中，您仅锁定修改操作（删除，添加），但您还应锁定对共享字段的所有访问。实际上这段代码根本不是线程安全的。我认为在这种情况下，ReaderWriterLockSlim - 将是最好的选择。
二。锁（这） - 很有想法。您应该使用特殊对象。
最后，我认为你的代码很乱，很难理解。也许你的班级解决了许多不同的任务也许你应该提取一些逻辑来分离类（例如创建受保护的字典作为单独的类）或其他东西。
使用ReaderWriterLockSlim的示例：
someSharedResource;
someSharedResourceRWLock = new ReaderWriterLockSlim();
一些阅读代码：
try
{
someSharedResourceRWLock.EnterReadLock();
//access to someSharedResource for reading
}
finally
{
someSharedResourceRWLock.ExitReadLock();
}
一些编写代码：
try
{
someSharedResourceRWLock.EnterWriteLock();
//access to someSharedResource for modifications
}
finally
{
someSharedResourceRWLock.ExitWriteLock();
}
答案 3 :(得分：0)
到目前为止给出的建议很棒，但我有一个你可能想要考虑的设计建议。替换这个：
private Dictionary<string, Socket> UsersOnline;
private ThreadSafeDictionary<string, Socket> UsersOnline
如果它适合您的需求，那么将业务逻辑与线程逻辑分开将是一种很好的方法。