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#ifndef _COUNTER_HPP_
#define _COUNTER_HPP_
#include <boost/shared_ptr.hpp>
#include <boost/thread.hpp>
#include <boost/thread/thread_time.hpp>
struct Counter;
typedef boost::shared_ptr<Counter> CounterPtr;
/**
* A synchronization mechanism with counter-like properties.
*
* To avoid memory corruption when unit tests fail, one should
* never store Counter objects on the stack. Instead, one should
* create them on the heap and use CounterPtr smart pointers.
*/
struct Counter {
struct timeout_expired { };
unsigned int value;
boost::mutex mutex;
boost::condition_variable cond;
static CounterPtr create_ptr() {
return CounterPtr(new Counter());
}
Counter() {
value = 0;
}
/**
* Wait until other threads have increment this counter to at least wanted_value.
* If this doesn't happen within <tt>timeout</tt> miliseconds, then a timeout_expired
* exception will be thrown.
*/
void wait_until(unsigned int wanted_value, unsigned int timeout = 1000) {
boost::unique_lock<boost::mutex> l(mutex);
while (value < wanted_value) {
if (!cond.timed_wait(l, boost::get_system_time() + boost::posix_time::milliseconds(timeout))) {
throw timeout_expired();
}
}
}
/** Increment the counter by one. */
void increment() {
boost::unique_lock<boost::mutex> l(mutex);
value++;
cond.notify_all();
}
};
#endif /* _COUNTER_HPP_ */