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// condition_variable::wait (with predicate)
#include <iostream> // std::cout
#include <thread> // std::thread, std::this_thread::yield
#include <mutex> // std::mutex, std::unique_lock
#include <condition_variable> // std::condition_variable
std::mutex mtx;
std::condition_variable cv;
int cargo = 0;
bool shipment_available() {return cargo!=0;}
void consume (int n) {
for (int i=0; i<n; ++i) {
std::unique_lock<std::mutex> lck(mtx);
cv.wait(lck,shipment_available);
// consume:
std::cout << cargo << '\n';
cargo=0;
}
}
int main ()
{
std::thread consumer_thread (consume,10);
// produce 10 items when needed:
for (int i=0; i<10; ++i) {
while (shipment_available()) std::this_thread::yield();
std::unique_lock<std::mutex> lck(mtx);
cargo = i+1;
cv.notify_one();
}
consumer_thread.join();
return 0;
}
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