update ceph source to reef 18.1.2

[ceph.git] / ceph / src / seastar / include / seastar / core / lowres_clock.hh

diff --git a/ceph/src/seastar/include/seastar/core/lowres_clock.hh b/ceph/src/seastar/include/seastar/core/lowres_clock.hh
index 2d683a87aa2749f1763de9ccc2cacc09fe59e376..27358f906765259ea08dd401ce9cc1f289b0e8ed 100644 (file)
--- a/ceph/src/seastar/include/seastar/core/lowres_clock.hh
+++ b/ceph/src/seastar/include/seastar/core/lowres_clock.hh
@@ -38,64 +38,12 @@ namespace seastar {
 class lowres_clock;
 class lowres_system_clock;
 
-/// \cond internal
-
-class lowres_clock_impl final {
-public:
-    using base_steady_clock = std::chrono::steady_clock;
-    using base_system_clock = std::chrono::system_clock;
-
-    // The clocks' resolutions are 10 ms. However, to make it is easier to do calculations with
-    // `std::chrono::milliseconds`, we make the clock period 1 ms instead of 10 ms.
-    using period = std::ratio<1, 1000>;
-
-    using steady_rep = base_steady_clock::rep;
-    using steady_duration = std::chrono::duration<steady_rep, period>;
-    using steady_time_point = std::chrono::time_point<lowres_clock, steady_duration>;
-
-    using system_rep = base_system_clock::rep;
-    using system_duration = std::chrono::duration<system_rep, period>;
-    using system_time_point = std::chrono::time_point<lowres_system_clock, system_duration>;
-
-    static steady_time_point steady_now() noexcept {
-        auto const nr = counters::_steady_now.load(std::memory_order_relaxed);
-        return steady_time_point(steady_duration(nr));
-    }
-
-    static system_time_point system_now() noexcept {
-        auto const nr = counters::_system_now.load(std::memory_order_relaxed);
-        return system_time_point(system_duration(nr));
-    }
-
-    // For construction.
-    friend class smp;
-private:
-    // Both counters are updated by cpu0 and read by other cpus. Place them on their own cache line to avoid false
-    // sharing.
-    struct alignas(seastar::cache_line_size) counters final {
-        static std::atomic<steady_rep> _steady_now;
-        static std::atomic<system_rep> _system_now;
-    };
-
-    // The timer expires every 10 ms.
-    static constexpr std::chrono::milliseconds _granularity{10};
-
-    // High-resolution timer to drive these low-resolution clocks.
-    timer<> _timer{};
-
-    static void update() noexcept;
-
-    // Private to ensure that static variables are only initialized once.
-    // might throw when arming timer.
-    lowres_clock_impl();
-};
-
 /// \endcond
 
 //
 /// \brief Low-resolution and efficient steady clock.
 ///
-/// This is a monotonic clock with a granularity of 10 ms. Time points from this clock do not correspond to system
+/// This is a monotonic clock with a granularity of ~task_quota. Time points from this clock do not correspond to system
 /// time.
 ///
 /// The primary benefit of this clock is that invoking \c now() is inexpensive compared to
@@ -105,19 +53,23 @@ private:
 ///
 class lowres_clock final {
 public:
-    using rep = lowres_clock_impl::steady_rep;
-    using period = lowres_clock_impl::period;
-    using duration = lowres_clock_impl::steady_duration;
-    using time_point = lowres_clock_impl::steady_time_point;
-
+    using rep = std::chrono::steady_clock::rep;
+    using period = std::chrono::steady_clock::period;
+    using duration = std::chrono::steady_clock::duration;
+    using time_point = std::chrono::time_point<lowres_clock, duration>;
     static constexpr bool is_steady = true;
-
+private:
+    // Use inline variable to prevent the compiler from introducing an initialization guard
+    inline static thread_local time_point _now;
+public:
     ///
     /// \note Outside of a Seastar application, the result is undefined.
     ///
     static time_point now() noexcept {
-        return lowres_clock_impl::steady_now();
+        return _now;
     }
+
+    static void update() noexcept;
 };
 
 ///
@@ -131,18 +83,21 @@ public:
 ///
 class lowres_system_clock final {
 public:
-    using rep = lowres_clock_impl::system_rep;
-    using period = lowres_clock_impl::period;
-    using duration = lowres_clock_impl::system_duration;
-    using time_point = lowres_clock_impl::system_time_point;
-
-    static constexpr bool is_steady = lowres_clock_impl::base_system_clock::is_steady;
-
+    using rep = std::chrono::system_clock::rep;
+    using period = std::chrono::system_clock::period;
+    using duration = std::chrono::system_clock::duration;
+    using time_point = std::chrono::time_point<lowres_system_clock, duration>;
+    static constexpr bool is_steady = false;
+private:
+    // Use inline variable to prevent the compiler from introducing an initialization guard
+    inline static thread_local time_point _now;
+    friend class lowres_clock; // for updates
+public:
     ///
     /// \note Outside of a Seastar application, the result is undefined.
     ///
     static time_point now() noexcept {
-        return lowres_clock_impl::system_now();
+        return _now;
     }
 
     static std::time_t to_time_t(time_point t) noexcept {