The IO Completion Port C Class (IOCP.h)

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The simple CIOCP C++ class, shown in Listing B-5, just wraps the Windows I/O completion port kernel object functions. All the methods are inline, so there is no performance penalty when you use the class. Wrapping the functions allows you to manipulate an I/O completion port object with a more logical interface.

Listing B-5. The IOCP.h header file

 
IOCP.h
 /****************************************************************************** Module:  IOCP.h Notices: Copyright (c) 2000 Jeffrey Richter Purpose: This class wraps an I/O Completion Port.          See Appendix B. ******************************************************************************/ #pragma once   // Include this header file once per compilation unit /////////////////////////////////////////////////////////////////////////////// #include "..\CmnHdr.h"              // See Appendix A. /////////////////////////////////////////////////////////////////////////////// class CIOCP { public:    CIOCP(int nMaxConcurrency = -1) {        m_hIOCP = NULL;        if (nMaxConcurrency != -1)          (void) Create(nMaxConcurrency);    }    ~CIOCP() {        if (m_hIOCP != NULL)           chVERIFY(CloseHandle(m_hIOCP));     }    BOOL Create(int nMaxConcurrency = 0) {       m_hIOCP = CreateIoCompletionPort(          INVALID_HANDLE_VALUE, NULL, 0, nMaxConcurrency);       chASSERT(m_hIOCP != NULL);       return(m_hIOCP != NULL);    }    BOOL AssociateDevice(HANDLE hDevice, ULONG_PTR CompKey) {       BOOL fOk = (CreateIoCompletionPort(hDevice, m_hIOCP, CompKey, 0)           == m_hIOCP);       chASSERT(fOk);       return(fOk);    }    BOOL AssociateSocket(SOCKET hSocket, ULONG_PTR CompKey) {       return(AssociateDevice((HANDLE) hSocket, CompKey));    }     BOOL PostStatus(ULONG_PTR CompKey, DWORD dwNumBytes = 0,        OVERLAPPED* po = NULL) {       BOOL fOk = PostQueuedCompletionStatus(m_hIOCP, dwNumBytes, CompKey, po);       chASSERT(fOk);       return(fOk);    }    BOOL GetStatus(ULONG_PTR* pCompKey, PDWORD pdwNumBytes,       OVERLAPPED** ppo, DWORD dwMilliseconds = INFINITE) {       return(GetQueuedCompletionStatus(m_hIOCP, pdwNumBytes,           pCompKey, ppo, dwMilliseconds));    } private:    HANDLE m_hIOCP; }; ///////////////////////////////// End of File /////////////////////////////////