Roman Morokutti
The code sample I used is from the boost documentation of the thread's library at:
http://www.boost.org/doc/libs/1_39_0/doc/html/thread/time.html
Here's the code:
int main(int argc, char** argv) {
boost::system_time const timeout = boost::get_system_time() + boost::posix_time::milliseconds(500);
extern bool done = true; extern boost::mutex m; extern boost::condition_variable cond;
boost::unique_lockboost::mutex lk(m); while (!done) { if (!cond.timed_wait(lk, timeout)) { throw "timed out"; } }
return (EXIT_SUCCESS); }
But as with the code provided on the net (see link above) where the variables (done, m, cond) are specified with extern, the linker always moaned that it couldn't resolve those symbols. So IMHO this example is not well suited for a standalone example.
If you declare variables "extern" at block scope then you need to provide a declaration at global scope too. The point of declaring them extern in the example is to say that these variables are accessible to, and used by, code elsewhere in the system. In particular, another thread will lock the mutex, set done to true and then notify the condition variable. Anthony -- Author of C++ Concurrency in Action | http://www.manning.com/williams just::thread C++0x thread library | http://www.stdthread.co.uk Just Software Solutions Ltd | http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976