使用Win32 API在C++中使用多线程创建多个文件

Question

我正尝试在笔驱动器中创建文件。如果笔驱动器不存在，线程应暂停。当它插入它应该恢复。这是我试过的代码，但它不能正常工作。谁能帮我？

#include "stdafx.h" 
    #include <Windows.h> 
    #include <Strsafe.h> 
    #include <WinBase.h> 


     LPCTSTR Disk=L"E:\"; 

     LPTSTR drive_Name=L"E:\\demo"; 

     CRITICAL_SECTION section; 


     #define BUFFER_SIZE 1024 
     #define count 10 

     HANDLE Write_Handle[10],Open_Handle[10],read_Handle[10] ; 

     DWORD WINAPI check_Thread(LPVOID lpParameter) 

     { 

     int *nThreadNo = (int*)lpParameter; 

     while(1) 

     { 

       if(GetDiskFreeSpaceExW(Disk,NULL,NULL,NULL)) 

       { 

        ResumeThread(Write_Handle[*nThreadNo]); 
        ResumeThread(read_Handle[*nThreadNo]); 
       } 
       else 
       { 
        SuspendThread(Write_Handle[*nThreadNo]); 
        SuspendThread(read_Handle[*nThreadNo]); 
       } 
      } 

     } 


     DWORD WINAPI Write_Thread(LPVOID lpParameter) 
     { 
      DWORD g_tid = GetCurrentThreadId(); 
      _tprintf(_T(" write thread id %d\n"),g_tid); 
      LPCWSTR filename=(LPCWSTR)lpParameter; 
      HANDLE ofile; 
      EnterCriticalSection(&section); 
      ofile=CreateFileW(filename,GENERIC_WRITE,FILE_SHARE_READ,NULL,OPEN_ALWAYS,NULL, NULL); 
      int d; 
       d=GetLastError(); 
       if(ERROR_SUCCESS!=GetLastError()) 
       { 
        _tprintf(_T("error values in open thread %d \n"),GetLastError()); 
        _tprintf(_T("filename %s \n"),filename); 
       } 

      const int filesizeinKB = 1024; 
      BOOL bError; 
      DWORD dwBytesWritten=0; 
      WCHAR ReadBuffer[BUFFER_SIZE] = {0}; 
      int i; 


      for(i = 0; i <= BUFFER_SIZE; i++) 
      { 
       ReadBuffer[i] = (char)(i%26 + 'a'); 
      } 
      for (i = 0; i <= filesizeinKB; i++) 
      { 
       SetLastError(0); 
       bError= WriteFile(ofile, ReadBuffer-1, BUFFER_SIZE,&dwBytesWritten, NULL); 
       bError=GetLastError(); 

       if (ERROR_SUCCESS!=GetLastError()) 
       { _tprintf(_T("error value in write %d\n"),GetLastError()); 
        _tprintf(_T(" Write Error...\n")); 
         return 1; 
       } 

      } 
      SetLastError(0); 
      CloseHandle(ofile); 
      _tprintf(_T("write close error values %d\n"),GetLastError()); 
      LeaveCriticalSection(&section); 
      return 1; 
     } 


     DWORD WINAPI Read_Thread(LPVOID lpParameter) 
     { 
      HANDLE ofile; 
      DWORD g_tid = GetCurrentThreadId(); 
      _tprintf(_T(" write thread id %d\n"),g_tid); 
      LPCWSTR filename=(LPCWSTR)lpParameter; 
      EnterCriticalSection(&section); 
      ofile=CreateFileW(filename,GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_ALWAYS,NULL, NULL); 
      int d; 
       d=GetLastError(); 
       if(ERROR_SUCCESS!=GetLastError()) 
       { 
        _tprintf(_T("error values in open thread %d \n"),GetLastError()); 
        _tprintf(_T("filename %s \n"),filename); 
       } 

      DWORD dwBytesRead=0; 
      WCHAR ReadBuffer[BUFFER_SIZE] = {0}; 
      _tprintf(_T(" read thread \n")); 
      SetLastError(0); 
      int err; 

      ReadFile(ofile, ReadBuffer, (BUFFER_SIZE-1), &dwBytesRead, NULL); 

       err=GetLastError(); 
       _tprintf(_T("read error values %d \n"),GetLastError()); 
       if(ERROR_SUCCESS!=GetLastError()) 
       { 
        _tprintf(L"reading failed \n"); 
        return 0; 
       } 
       SetLastError(0); 
       CloseHandle(ofile); 
       err=GetLastError(); 
       _tprintf(_T("close error values %d\n"),GetLastError()); 
       LeaveCriticalSection(&section); 
       return 1; 
     } 


     int _tmain(int argc, _TCHAR* argv[]) 
     { 

      unsigned int myCounter = 0; 
      DWORD WritethreadID,OpenThreadID,ReadthreadID; 
      HANDLE check_Handle; 
      DWORD exThread; 
      TCHAR filename[100]; 
      HANDLE hfile; 
      INT bsize=100; 
      int i=0; 

      InitializeCriticalSection (&section); 
      CreateDirectory(drive_Name,NULL); 

      for(i=0;i<5;i++) 
      { 
       SetLastError(0); 
       StringCchPrintf(filename,bsize, TEXT("%s\\file_%d.txt"),drive_Name,i); 
       hfile=CreateFileW(filename,GENERIC_WRITE|GENERIC_READ,NULL,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); 

       if (hfile == INVALID_HANDLE_VALUE) 
       { 
        _tprintf(_T("invalid handle \n")); 

       } 
       _tprintf(_T("file created %s\n"),filename); 
       CloseHandle(hfile); 

       Write_Handle[i] =CreateThread(0, 0, Write_Thread, filename, CREATE_SUSPENDED, &WritethreadID); 
       SetThreadPriority(Write_Handle[i],2); 
       _tprintf(_T("write thread id is %d\n"),WritethreadID); 
       read_Handle[i]=CreateThread(0, 0, Read_Thread, filename, CREATE_SUSPENDED, &ReadthreadID); 
       SetThreadPriority(read_Handle[i],1); 
       _tprintf(_T("read thread id is %d\n "),ReadthreadID); 
       check_Handle =CreateThread(0, 0, check_Thread,(void*)&i ,0,&OpenThreadID); 
      } 
      for (i=0; i<count; ++i) 
      { 
       WaitForSingleObject(Write_Handle[i],INFINITE); 
       if (!GetExitCodeThread(Write_Handle, &exThread)) 
       { 
        _tprintf(_T("close thread %08X\n"),GetLastError()); 

       } 
       SetLastError(0); 
       CloseHandle(Write_Handle[i]); 
       _tprintf(_T("close thread %08X\n"),GetLastError()); 
       WaitForSingleObject(read_Handle[i],INFINITE); 
       if (!GetExitCodeThread(read_Handle, &exThread)) 
       { 
        _tprintf(_T("GetExitCodeThread %08X\n"),GetLastError()); 
       } 
       SetLastError(0); 
       CloseHandle(read_Handle[i]); 
       _tprintf(_T("GetExitCodeThread %08X\n"),GetLastError()); 

       CloseHandle(check_Thread); 

      } 

      DeleteCriticalSection(&section); 
      return 1; 

     } 

Answer 1

如果您在移除驱动器时已经打开了USB驱动器的文件句柄，那些文件句柄将变为无效。重新插入USB驱动器将而不是重建这些句柄，以便您可以在恢复线程后继续。

你将需要：

• 检测当设备被删除，并关闭那些现在破碎手柄
• 当设备被插入，再次打开该文件，并继续无论你在做

Answer 2

您的错误处理程序正在返回而无需调用LeaveCriticalSection，从而将CS锁定并无限期地阻止其他线程。从EnterCriticalSection docs:

• 如果一个线程终止，同时它有一个关键部分的所有权， 的关键部分的状态是不确定的。

这些情况还会使文件句柄处于打开状态。