bool frontBlock(T& t, duration_type timeout) const
{
boost::mutex::scoped_lock lock(mutex_);
bool gotValue = false;
if (timeout.count() > 0)
{
if (deque_.empty())
{
available_.wait_for(lock, timeout);
}
if (!deque_.empty())
{
t = deque_.front();
gotValue = true;
}
}
else
{
while (deque_.empty())
{
available_.wait(lock);
}
t = deque_.front();
gotValue = true;
}
return gotValue;
}
/// Estimate the necessary number of buckets
std::size_t bucket_count(
duration_type measurement_period, duration_type sampling_period) {
if (sampling_period <= duration_type(0)) {
std::ostringstream os;
os << "jb::event_rate_estimate - sampling period ("
<< sampling_period.count() << ") must be a positive number";
throw std::invalid_argument(os.str());
}
if (sampling_period > measurement_period) {
std::ostringstream os;
os << "jb::event_rate_estimate - measurement period ("
<< measurement_period.count() << ") is smaller than sampling period ("
<< sampling_period.count() << ")";
throw std::invalid_argument(os.str());
}
if ((measurement_period % sampling_period).count() != 0) {
std::ostringstream os;
os << "jb::event_rate_estimate - measurement period ("
<< measurement_period.count()
<< ") must be a multiple of the sampling period ("
<< sampling_period.count() << ")";
throw std::invalid_argument(os.str());
}
// ... because measurement_period and sampling_period are positive
// numbers N will be a positive number ...
typedef typename duration_type::rep rep;
typedef typename std::make_unsigned<rep>::type unsigned_rep;
unsigned_rep N = measurement_period / sampling_period;
// ... beware, the type may be larger than what can be stored in
// an std::size_t (weird segmented memory platforms, yuck) ...
if (N >= std::numeric_limits<std::size_t>::max()) {
std::ostringstream os;
os << "jb::event_rate_estimate - measurement period ("
<< measurement_period.count() << ") is too large for sampling period ("
<< sampling_period.count() << ")";
throw std::invalid_argument(os.str());
}
return static_cast<std::size_t>(N);
}