Back off on reconnect rate

src/backoff.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <stdint.h>
+#include <algorithm>
+#include <random>
+
+struct Backoff
+{
+    int64_t minAmount;
+    int64_t maxAmount;
+    int64_t current;
+    int fails;
+    std::mt19937_64 randGenerator;
+    std::uniform_real_distribution<> randDistribution;
+
+    double rand01() {
+        return randDistribution(randGenerator);
+    }
+
+    Backoff(int64_t min, int64_t max)
+    : minAmount(min)
+    , maxAmount(max)
+    , current(min)
+    , fails(0)
+    {}
+
+    void reset()
+    {
+        fails = 0;
+        current = minAmount;
+    }
+
+    int64_t nextDelay()
+    {
+        ++fails;
+        int64_t delay = (int64_t)((double)current * 2.0 * rand01());
+        current = std::min(current + delay, maxAmount);
+        return current;
+    }
+};
+