Use an exponential backoff when deciding how long we need to wait for reconnects (#2892)

Co-authored-by: Leon Richardt <leon.richardt@gmail.com>

src/util/ExponentialBackoff.hpp

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <algorithm>
+#include <chrono>
+
+namespace chatterino {
+
+// Yes, you can't specify the base 😎 deal with it
+template <unsigned maxSteps>
+class ExponentialBackoff
+{
+public:
+    /**
+     * Creates an object helping you make exponentially (with base 2) backed off times.
+     *
+     * @param start The start time in milliseconds
+     * @param maxSteps The max number of progressions we will take before stopping
+     *
+     * For example, ExponentialBackoff(10ms, 3) would have the next() function return 10ms, 20ms, 40ms, 40ms, ..., 40ms
+     **/
+    ExponentialBackoff(const std::chrono::milliseconds &start)
+        : start_(start)
+        , step_{1}
+    {
+        static_assert(maxSteps > 1, "maxSteps must be higher than 1");
+    }
+
+    /**
+     * Return the current number in the progression and increment the step until the next one (assuming we're not at the cap)
+     *
+     * @returns current step in milliseconds
+     **/
+    [[nodiscard]] std::chrono::milliseconds next()
+    {
+        auto next = this->start_ * (1 << (this->step_ - 1));
+
+        this->step_ += 1;
+
+        if (this->step_ >= maxSteps)
+        {
+            this->step_ = maxSteps;
+        }
+
+        return next;
+    }
+
+    /**
+     * Reset the progression back to its initial state
+     **/
+    void reset()
+    {
+        this->step_ = 1;
+    }
+
+private:
+    const std::chrono::milliseconds start_;
+    unsigned step_;
+};
+
+}  // namespace chatterino