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#pragma once
#include <atomic>
#include <chrono>
namespace NUnifiedAgent {
class AtomicOneSecondThrottler {
public:
// The current time in seconds by AtomicOneSecondThrottler version.
uint64_t static inline Now() {
return std::chrono::duration_cast<std::chrono::seconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count()
// Add one second, because the steady clock starts after the
// system reboot, and at the first moment, it's zero, and the
// last operation is also zero.
+ 1;
}
// Check if we may do the operation.
inline bool May() noexcept {
return LastOp_.load(std::memory_order_acquire) < Now();
}
// Check if we can do it right now. Book the limits.
inline bool Do() noexcept {
auto now = Now();
auto last_op_expected = LastOp_.load(std::memory_order_acquire);
// Early check that we can do operation.
if (last_op_expected >= now) {
// It means that somebody has already taken our second, or maybe
// this thread is stuck in the past.
return false;
}
// Place our second in the LastOp_,
// if false, that means somebody replaced last_op_expected value.
return LastOp_.compare_exchange_strong(last_op_expected, now,
std::memory_order_acq_rel);
}
private:
// Last operation time
std::atomic<uint64_t> LastOp_{0};
static_assert(decltype(LastOp_)::is_always_lock_free,
"AtomicOneSecondThrottler::LastOp_ must be always lock-free");
};
} // namespace NUnifiedAgent
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