Reimplementd IX with OpenSSL

ixwebsocket/IXExponentialBackoff.cpp

@@ -0,0 +1,44 @@
+/*
+ *  IXExponentialBackoff.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2017-2019 Machine Zone, Inc. All rights reserved.
+ */
+
+#include "IXExponentialBackoff.h"
+
+#include <cmath>
+
+namespace ix
+{
+    uint32_t calculateRetryWaitMilliseconds(uint32_t retryCount,
+                                            uint32_t maxWaitBetweenReconnectionRetries,
+                                            uint32_t minWaitBetweenReconnectionRetries)
+    {
+        // It's easy with a power function to go beyond 2^32, and then 
+        // have unexpected results, so prepare for that
+        const uint32_t maxRetryCountWithoutOverflow = 26;
+
+        uint32_t waitTime = 0;
+        if (retryCount < maxRetryCountWithoutOverflow)
+        {
+            waitTime = std::pow(2, retryCount) * 100;
+        }
+
+        if (waitTime < minWaitBetweenReconnectionRetries)
+        {
+            waitTime = minWaitBetweenReconnectionRetries;
+        }
+
+        if (waitTime > maxWaitBetweenReconnectionRetries)
+        {
+            waitTime = maxWaitBetweenReconnectionRetries;
+        }
+
+        if (retryCount >= maxRetryCountWithoutOverflow)
+        {
+            waitTime = maxWaitBetweenReconnectionRetries;
+        }
+
+        return waitTime;
+    }
+} // namespace ix