intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 40 insertions, 0 deletions

diff --git a/util/system/spin_wait.cpp b/util/system/spin_wait.cpp
new file mode 100644
index 0000000000..e27045e74f
--- /dev/null
+++ b/util/system/spin_wait.cpp
@@ -0,0 +1,40 @@
+#include "spin_wait.h"
+#include "yield.h"
+#include "compat.h"
+#include "thread.h"
+#include "spinlock.h"
+
+#include <util/digest/numeric.h>
+#include <util/generic/utility.h>
+
+template <class T>
+static inline T RandomizeSleepTime(T t) noexcept {
+    static TAtomic counter = 0;
+    const T rndNum = IntHash((T)AtomicIncrement(counter));
+
+    return (t * (T)4 + (rndNum % t) * (T)2) / (T)5;
+}
+
+//arbitrary values
+#define MIN_SLEEP_TIME 500
+#define MAX_SPIN_COUNT 0x7FF
+
+TSpinWait::TSpinWait() noexcept
+    : T(MIN_SLEEP_TIME)
+    , C(0)
+{
+}
+
+void TSpinWait::Sleep() noexcept {
+    ++C;
+
+    if (C == MAX_SPIN_COUNT) {
+        ThreadYield();
+    } else if ((C & MAX_SPIN_COUNT) == 0) {
+        usleep(RandomizeSleepTime(T));
+
+        T = Min<unsigned>((T * 3) / 2, 20000);
+    } else {
+        SpinLockPause();
+    }
+}