高性能大容量SOCKET并发（五）：锁和对象分离

锁和对象一起封装的危险

在多线程编写中，绝大多数编码风格喜欢把锁和要访问的对象封装在同一个对象，释放对象的时候也释放锁，这样会造成死锁。我们写一个测试例子，我们创建一个锁，把锁锁住，然后再创建一个线程，一直不停的等待锁返回，然后我们把锁释放，这时线程就死锁，代码如下：

定义接口：

{ TSocketHandles }constructor TSocketHandles.Create;begin  FList := TList.Create;  FIdleList := TList.Create;  FLock := TCriticalSection.Create;end;destructor TSocketHandles.Destroy;begin  Clear;  FList.Free;  FIdleList.Free;  FLock.Free;  inherited;end;function TSocketHandles.GetItems(const AIndex: Integer): PClientSocket;begin  Result := FList[AIndex];end;function TSocketHandles.GetCount: Integer;begin  Result := FList.Count;end;procedure TSocketHandles.Clear;var  i: Integer;  ClientSocket: PClientSocket;begin  for i := 0 to Count - 1 do  begin    ClientSocket := Items[i];    ClientSocket.Lock.Free;    ClientSocket.SocketHandle.Free;    Dispose(ClientSocket);  end;  FList.Clear;  for i := 0 to FIdleList.Count - 1 do  begin    ClientSocket := FIdleList[i];    ClientSocket.Lock.Free; //释放锁    Dispose(ClientSocket);  end;  FIdleList.Clear;end;procedure TSocketHandles.Lock;begin  FLock.Enter;end;procedure TSocketHandles.UnLock;begin  FLock.Leave;end;function TSocketHandles.Add(ASocketHandle: TSocketHandle): Integer;var  ClientSocket: PClientSocket;begin  if FIdleList.Count > 0 then //先在空余中查找  begin    ClientSocket := FIdleList[0];    FIdleList.Delete(0);  end  else //否则创建一个  begin    New(ClientSocket);    ClientSocket.Lock := TCriticalSection.Create;  end;  ClientSocket.SocketHandle := ASocketHandle;  ASocketHandle.FLock := ClientSocket.Lock;  Result := FList.Add(ClientSocket);end;procedure TSocketHandles.Delete(const AIndex: Integer);var  ClientSocket: PClientSocket;begin  ClientSocket := FList[AIndex];  ClientSocket.Lock.Enter;  try    ClientSocket.SocketHandle.Free;    ClientSocket.SocketHandle := nil;  finally    ClientSocket.Lock.Leave;  end;  FList.Delete(AIndex);  if FIdleList.Count > MAX_IDLELOCK then //如果达到最大空闲个数，则释放    Dispose(ClientSocket)  else    FIdleList.Add(ClientSocket);end;procedure TSocketHandles.Delete(ASocketHandle: TSocketHandle);var  i, iIndex: Integer;begin  iIndex := -1;  for i := 0 to Count - 1 do  begin    if Items[i].SocketHandle = ASocketHandle then    begin      iIndex := i;      Break;    end;  end;  if iIndex <> -1 then  begin    Delete(iIndex);  end;end;

IOCPDemoSvr下载地址：http://download.csdn.net/detail/sqldebug_fan/4510076

免责声明：此代码只是为了演示IOCP编程，仅用于学习和研究，切勿用于商业用途。水平有限，错误在所难免，欢迎指正和指导。邮箱地址：fansheng_hx@163.com