Made ApplyJitter a separate function in jitter.h. Reimplemented BackoffStrategy with it

3 files changed, 43 insertions, 4 deletions

diff --git a/yt/yt/core/misc/backoff_strategy.cpp b/yt/yt/core/misc/backoff_strategy.cpp
index c902ca5b5d6..4b9e5871338 100644
--- a/yt/yt/core/misc/backoff_strategy.cpp
+++ b/yt/yt/core/misc/backoff_strategy.cpp
@@ -1,4 +1,5 @@
 #include "backoff_strategy.h"
+#include "jitter.h"
 
 #include <util/random/normal.h>
 
@@ -58,10 +59,12 @@ TDuration TBackoffStrategy::GetBackoff() const
 
 void TBackoffStrategy::ApplyJitter()
 {
-    auto rnd = StdNormalRandom<double>();
-    bool isNegative = rnd < 0;
-    auto jitter = std::abs(rnd) * Options_.BackoffJitter * Backoff_;
-    BackoffWithJitter_ = isNegative ? Backoff_ - jitter : Backoff_ + jitter;
+    BackoffWithJitter_ = ::NYT::ApplyJitter(Backoff_, Options_.BackoffJitter, +[]{
+        //! StdNormalRandom produces [-6.660, 6.660] according to Wiki
+        const double StdNormalRandomMaxValue = 7.0;
+
+        return StdNormalRandom<double>() / StdNormalRandomMaxValue;
+    });
 }
 
 
diff --git a/yt/yt/core/misc/jitter.h b/yt/yt/core/misc/jitter.h
new file mode 100644
index 00000000000..7d3935b0d63
--- /dev/null
+++ b/yt/yt/core/misc/jitter.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include "public.h"
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+//! TRandomGenerator is required to produce numbers only in range [-1, 1].
+//! Will crash otherwise
+template <CScalable<double> TValue, class TRandomGenerator>
+    requires std::is_invocable_r<double, TRandomGenerator>::value
+constexpr inline TValue ApplyJitter(TValue average, double jitter, const TRandomGenerator& randomGenerator)
+{
+    YT_VERIFY(jitter >= 0 && jitter <= 1);
+
+    double rnd = randomGenerator();
+
+    YT_VERIFY(std::abs(rnd) <= 1);
+
+    double multiplier = static_cast<double>(1) + jitter * rnd;
+
+    return average * multiplier;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
diff --git a/yt/yt/core/misc/public.h b/yt/yt/core/misc/public.h
index 556fb71a029..a7ee5641b52 100644
--- a/yt/yt/core/misc/public.h
+++ b/yt/yt/core/misc/public.h
@@ -172,4 +172,12 @@ DECLARE_REFCOUNTED_STRUCT(IMemoryReferenceTracker)
 
 ////////////////////////////////////////////////////////////////////////////////
 
+template <class TObject, class TScalar>
+concept CScalable = requires (TObject object, TScalar scalar)
+{
+    { object * scalar } -> std::same_as<TObject>;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
 } // namespace NYT