feat: Add ThrottledInvoker utility

Common use case is throttling logging.

SDB-9889

Author: bnbajwa

toolbox/sys/Time.hpp

@@ -468,6 +468,27 @@ struct TypeTraits<WallTime> {
     }
 };
 
+/// Throttles the invocation of a callable to not exceed a specified rate.
+/// The rate is controlled by a cooldown interval.
+class ThrottledInvoker {
+  public:
+    explicit ThrottledInvoker(Seconds cooldown_interval)
+    : cooldown_interval_(cooldown_interval) {}
+
+    template <typename Callable>
+    void operator()(MonoTime now, Callable&& callable)
+    {
+        if (duration_cast<Seconds>(now - last_time_invoked_) >= cooldown_interval_) {
+            last_time_invoked_ = now;
+            std::forward<Callable>(callable)();
+        }
+    }
+
+  private:
+    const Seconds cooldown_interval_{};
+    MonoTime last_time_invoked_{};
+};
+
 } // namespace util
 } // namespace toolbox
 

toolbox/sys/Time.ut.cpp

@@ -124,4 +124,31 @@ BOOST_AUTO_TEST_CASE(PutTimeOutput2)
     BOOST_CHECK_EQUAL(stream.str(), "20180824T05:32:29.001001001");
 }
 
+BOOST_AUTO_TEST_CASE(ThrottledInvokerCheck)
+{
+    constexpr auto threshold = 1s;
+    ThrottledInvoker throttler{threshold};
+
+    std::size_t count = 0;
+    auto now = MonoClock::now();
+
+    auto check_throttling = [&] {
+        const auto end = now + threshold;
+        while (now <= end) {
+            throttler(now, [&]() { ++count; });
+            now = MonoClock::now();
+        }
+    };
+
+    check_throttling();
+    BOOST_CHECK_EQUAL(count, 1);
+
+    now = MonoClock::now() + threshold;
+
+    // the throttle should invoke again now
+    check_throttling();
+    BOOST_CHECK_EQUAL(count, 2);
+}
+
+
 BOOST_AUTO_TEST_SUITE_END()