Multi Threads... just a simple example plz...
quote:Original post by mutexCCriticalSection g_cs;CString g_sData; // data that requires synchronizationUINT ThreadOne(LPVOID param){ g_cs.Lock(); sData = "Blah"; g_cs.Unlock(); return 0;}
If unluckily sData got sick and throws an exception, your g_cs won''t be unlocked... and you will have some ''deadlock'', resulting ThreadTwo waiting......
quote:If unluckily sData got sick and throws an exception, your g_cs won't be unlocked... and you will have some 'deadlock', resulting ThreadTwo waiting......
Good point!
The typical solution is to write a guard class that will automatically lock and unlock the critical section for you.
class CGuard{ CCriticalSection& cs;public: CGuard (CCriticalSection& cs) : cs (cs) { cs. Lock (); } ~CGuard (CCriticalSection& cs) { cs.Unlock (); }};CCriticalSection g_cs;CString g_sData; // data that requires synchronizationUINT ThreadOne(LPVOID param){ CGuard MyGuard (g_cs); sData = "Blah"; return 0;} Remember that CGuard will synchronize access to your whole function, which is probably not ideal. Normally, you should only synchronize access to the data and spend as little time within the synchronized section. After all you wish these threads to run asynchronously, right?
Here's how:
UINT ThreadOne(LPVOID param){ // <insert code to do other stuff> { CGuard MyGuard (g_cs); // <- it is locked here sData = "Blah"; } // <- it is unlocked here // <insert code to do other stuff> return 0;} Although I thought that it was not a good idea to throw into system code (e.g., out of a thread function, out of a window function, etc.). If you use exceptions, you should do this to catch any exceptions that might be thrown out of the thread function:
UINT ThreadOne(LPVOID param){ try { // <insert code to do other stuff> { CGuard MyGuard (g_cs); sData = "Blah"; } // <insert code to do other stuff> } catch (...) { // <insert code to handle exception> } return 0;} [edited by - null_pointer on September 11, 2002 9:35:08 AM]
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cool thx guys... I''ll look over all this and get it going....
thanks for all your help...
thanks for all your help...
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