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

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

tests/src/ExponentialBackoff.cpp

@@ -0,0 +1,58 @@
+#include "util/ExponentialBackoff.hpp"
+
+#include <gtest/gtest.h>
+
+using namespace chatterino;
+
+TEST(ExponentialBackoff, MaxSteps)
+{
+    using namespace std::literals::chrono_literals;
+
+    ExponentialBackoff<3> foo{10ms};
+
+    // First usage should be the start value
+    EXPECT_EQ(foo.next(), 10ms);
+    EXPECT_EQ(foo.next(), 20ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    // We reached the max steps, so we should continue returning the max value without increasing
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+}
+
+TEST(ExponentialBackoff, Reset)
+{
+    using namespace std::literals::chrono_literals;
+
+    ExponentialBackoff<3> foo{10ms};
+
+    // First usage should be the start value
+    EXPECT_EQ(foo.next(), 10ms);
+    EXPECT_EQ(foo.next(), 20ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    // We reached the max steps, so we should continue returning the max value without increasing
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+
+    foo.reset();
+
+    // After a reset, we should start at the beginning value again
+    EXPECT_EQ(foo.next(), 10ms);
+    EXPECT_EQ(foo.next(), 20ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    // We reached the max steps, so we should continue returning the max value without increasing
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+    EXPECT_EQ(foo.next(), 40ms);
+}
+
+TEST(ExponentialBackoff, BadMaxSteps)
+{
+    using namespace std::literals::chrono_literals;
+
+    // this will not compile
+    // ExponentialBackoff<1> foo{10ms};
+    // ExponentialBackoff<0> foo{10ms};
+    // ExponentialBackoff<-1> foo{10ms};
+}