Re: boost::mutex::scoped_lock conventions

"William E. Kempf" wrote: [...]

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How about moving this discussion to c.p.t.?

Well, just in case... <Forward Quoted>

Thanks... I currently can't access c.p.t. in any reasonable manner. I'm working to rectify this,

http://news.cis.dfn.de might help. ;-) but in the mean time, I appreciate the cross

post.

I'll wait a day or two and post a reply addressing some of your points to comp.programming.threads. You might also want to keep an eye on the discussion of "validity" of the following DCSI** pattern (not exposing thread_specific_ptr::release() or thread_specific_ptr::reset() to the clients... Butenhof believes that since <quote>You at least need to be sure all threads are "done" with the current key and will never read it again, because pthread_key_delete() cannot invalidate the key</quote>, the clients ("individual threads") should <quote>confirm that synchronization by clearing their value for the key</quote>). class stuff { /* ... */ }; class thing { public: thing(/* ... */) : /* ... */ stuff_shared_ptr(0) /* ... */ { /*...*/ } ~thing() { /* ... */ delete stuff_shared_ptr; /* ... */ } /* ... */ const stuff & stuff_instance(); /* ... */ private: /* ... */ mutex stuff_mtx; stuff * stuff_shared_ptr; thread_specific_ptr stuff_thread_ptr; /* ... */ }; const stuff & thing::stuff_instance() { // "lazy" one stuff * ptr; if (0 == (ptr = stuff_thread_ptr.get())) { { mutex::guard guard(stuff_mtx); if (0 == (ptr = stuff_shared_ptr)) ptr = stuff_shared_ptr = new stuff(/*...*/); } stuff_thread_ptr.set(ptr); } return *ptr; } the details can be found in "Double-checked locking and memory barriers" c.p.t. thread. regards, alexander. **) DCSI stands for double-checked serialized initialization. Two variations are known corrently: DCSI-MBR and DCS-TSD (TLS). There's also another DC-"pattern" -- double-checked concurrent initialization [DCCI]; using atomic<> with barriers and "CAS". -- "// Possible implementation for and <cthread> #include <thread> // for <cthread>, please remove the using-directive using namespace std;" -- ...