Gopi, First I don't think that this program need to be multithreaded, as all three operations are atomic, so if one operation is going on then you cann't invoke another operation, else it will currupt the list. So making this program as multithreaded will only create the extra load and you will not gain anything out of this.
Do share your thoughts. Regards, Vishal On Sun, Aug 16, 2009 at 11:54 PM, Gopi Krishna Komanduri < [email protected]> wrote: > > > Hi, > Below is the code related to threads. The main concept is , 1 thread > will insert into list (Threadproc1) , another thread deletes from > list(Threadproc3) and third thread (Threadproc2)just prints the values in > list. > > I used events for sync . But I am sure this is not thread safe as some > times I observer , anoither thread is getting executed while the current one > still running. Could you please suggest how to make it thread safe. > > Adv Thanks. > > #include<stdio.h> > #include<conio.h> > #include<tchar.h> > #include<atlstr.h> > #include<windows.h> > > typedef struct MyList > { > int i; > struct MyList *nxt; > > }MyList; > int val; > HANDLE hnd_event,file_handle; > > MyList *lst; > DWORD WINAPI ThreadProc1(LPVOID ptr) > { > WaitForSingleObject(hnd_event,INFINITE); > while(1) > { > ResetEvent(hnd_event); > file_handle= > CreateFile(_T("MyFile.txt"),GENERIC_WRITE|GENERIC_READ,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); > MyList *temp,*temp1; > temp = lst; > temp1 = (MyList *)malloc(1*sizeof(MyList )); > temp1->nxt = NULL; > > if(lst == NULL) > { > lst = temp1; > temp = lst; > // temp->nxt=NULL; > } > > else > { > temp = lst; > while(temp->nxt!=NULL) > temp = temp->nxt; > temp->nxt=temp1; > temp = temp->nxt; > } > temp->i = val; > temp->nxt = NULL; > val++; > CloseHandle(file_handle); > SetEvent(hnd_event); > } > return 1; > > > } > DWORD WINAPI ThreadProc2(LPVOID ptr) > { > WaitForSingleObject(hnd_event,INFINITE); > while(1) > { > ResetEvent(hnd_event); > DWORD written; > file_handle= > CreateFile(_T("MyFile.txt"),GENERIC_WRITE|GENERIC_READ,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); > > MyList *temp; > CString str; > str.Empty(); > > temp = lst; > if(!temp) > { > // printf("\n not yet filled"); > str=SysAllocString(_T("\n not yet filled.. In ThreadProc2")); > > } > else > { > while(temp) > { > printf("\n The val is %d",temp->i); > str.Empty(); > str.Format(_T("\n The val is %d",temp->i)); > temp = temp->nxt; > } > } > WriteFile(file_handle,str.GetBuffer(),str.GetLength()*2,&written,NULL); > CloseHandle(file_handle); > SetEvent(hnd_event); > } > return 1; > } > DWORD WINAPI ThreadProc3(LPVOID ptr) > { > WaitForSingleObject(hnd_event,INFINITE); > while(1) > { > ResetEvent(hnd_event); > file_handle= > CreateFile(_T("MyFile.txt"),GENERIC_WRITE|GENERIC_READ,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); > > MyList *temp,*temp1; > temp = lst; > CString str; > str.Empty(); > DWORD written; > if(!temp) > { > //printf("\n empty"); > str=SysAllocString(_T("\n empty")); > > WriteFile(file_handle,str.GetBuffer(),str.GetLength()*2,&written,NULL); > return 1; > } > /*if(temp->nxt == NULL) > { > printf("\n Now removing %d and list is free now",temp->i); > free(temp); > temp = NULL; > return 1; > } > while(temp->nxt->nxt) > { > temp = temp->nxt; > } > free(temp->nxt);*/ > while(temp->nxt) > temp = temp->nxt; > //printf("\n Now removing %d",temp->i); > str.Empty(); > str.Format(_T("\n Now removing %d",temp->i)); > WriteFile(file_handle,str.GetBuffer(),str.GetLength()*2,&written,NULL); > free(temp); > temp=NULL; > CloseHandle(file_handle); > SetEvent(hnd_event); > } > return 1; > > } > int main() > { > hnd_event = CreateEvent(NULL,false,true,_T("GopiEvent")); > file_handle= > CreateFile(_T("MyFile.txt"),GENERIC_WRITE|GENERIC_READ,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); > CloseHandle(file_handle); > HANDLE thread_handle[3]; > DWORD thid1,thid2,thid3; > > thread_handle[0]=CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ThreadProc1,NULL,CREATE_SUSPENDED,&thid1); > > thread_handle[1]=CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ThreadProc2,NULL,CREATE_SUSPENDED,&thid2); > > thread_handle[2]=CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ThreadProc3,NULL,CREATE_SUSPENDED,&thid2); > ResumeThread(thread_handle[0]); > ResumeThread(thread_handle[1]); > ResumeThread(thread_handle[2]); > WaitForMultipleObjects(3,thread_handle,true,INFINITE); > return 1; > > } > > Love Cricket? Check out live scores, photos, video highlights and more. > Click here http://cricket.yahoo.com > > [Non-text portions of this message have been removed] > > > -- Regards Vishal Thakur +919923206953 [Non-text portions of this message have been removed]
