added retryUtil for exponential backoff

src/main/java/com/microsoft/azure/kusto/kafka/connect/sink/RetryUtil.java

@@ -0,0 +1,38 @@
+package com.microsoft.azure.kusto.kafka.connect.sink;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+public class RetryUtil {
+
+  /**
+   * An arbitrary absolute maximum retry time.
+   */
+  public static final long MAX_RETRY_TIME_MS = TimeUnit.HOURS.toMillis(24);
+
+  public static long computeExponentialBackOffWithJitter(int retryAttempts, long initialRetryBackoffMs) {
+    if (initialRetryBackoffMs < 0) {
+      return 0;
+    }
+    if (retryAttempts < 0) {
+      return initialRetryBackoffMs;
+    }
+    long maxRetryTime = computeBackOffTime(retryAttempts, initialRetryBackoffMs);
+    return ThreadLocalRandom.current().nextLong(0, maxRetryTime);
+  }
+
+  public static long computeBackOffTime(int retryAttempts, long initialRetryBackoffMs) {
+    if (initialRetryBackoffMs < 0) {
+      return 0;
+    }
+    if (retryAttempts <= 0) {
+      return initialRetryBackoffMs;
+    }
+    if (retryAttempts > 32) {
+      // This would overflow the exponential algorithm ...
+      return MAX_RETRY_TIME_MS;
+    }
+    long result = initialRetryBackoffMs << retryAttempts;
+    return result < 0L ? MAX_RETRY_TIME_MS : Math.min(MAX_RETRY_TIME_MS, result);
+  }
+
+}